40th SiliconSympoSiumSympoSiumVictoria, BC • 31 May – 2 June 2007

Program and Abstracts

40th Silicon SympoSium

Victoria, BC • 31 May – 2 June 2007

Table of Contents

About the 40th Silicon Symposium 3

Sponsors 4

Program 6

History of the Silicon Symposium 11

Past, Present and Future Silicon Symposia 12

Alan G. MacDiarmid 1927 – 2007 15

Plenary Lecture Abstracts PL 1-3

Invited Lecture Abstracts I 1-8

Contributed Lecture Abstracts C 1-32

Poster Abstracts P 1-23

Author Index

Notes (blank pages for your note-taking)

40th Silicon SympoSium

Victoria, BC • 31 May – 2 June 2007

Location

Delta Victoria Ocean Pointe Resort and Spa in Victoria, BC, Canada.

Organizers

Lisa Rosenberg, University of Victoria Scott McIndoe, University of Victoria

Advisory Board

Kim M. Baines, University of Western Ontario Michael A. Brook, McMaster University William J. Leigh, McMaster University

Robert West, University of Wisconsin, Madison

Acknowledgements

Many thanks to our student volunteers:

Eric Derrah ~ Sarah Jackson ~ Andrea Kirby

Danielle Chisholm ~ Matthew Henderson ~ Krista Vikse

and to the staff of the Department of Chemistry, University of Victoria, in particular:

Shelley Henuset

Rosemary Pulez

3

Sponsors

The organizers would like to thank the following companies and organizations for their generous support of the 40th Silicon Symposium:

Silicon, Germanium, Tin and Metal-Organic Compounds

4

38th Silicon Symposium, University of Colorado at Boulder

The University of Victoria, in particular:

• Vice-President, Research • Department of Chemistry • Faculty of Science

The Organosilicon Research Centre University of Wisconsin-Madison Bruker Canada

The American Chemical Society, Petroleum Research Fund

5

Program

Thursday, May 31, 2007

Time Activity

2:30 pm

Registration opens

6:30 - 10:00

Opening reception at the Royal BC Museum

The Royal BC Museum is on the other side of the Inner Harbour from the Delta Hotel, on the corner of Belleville and Government Streets. It is an easy and picturesque walk of about 1.6 km (1 mile) across the bridge and down Wharf Street (which joins Government; see map below). Alternatively, water taxis leave from the Delta foreshore to the wharf in front of the Empress Hotel (curved line on map).

6

Friday, June 1, 2007

Time Session A (Ascot) Session B (Balfour)

8:50 am Opening Remarks

9:00 Chair: Robert West

*** PLENARY ***

Zakya Kafafi (PL-1) Efficient Conversion of Electrical Energy into Light Using Siloles and Silafluorenes

10:00 Coffee Break: Foyer/Chelsea

Chair: Tom Barton Chair: Barrett Eichler

10:20 Soichiro Kyushin (I-1) Silicon-Silicon π Single Bond

Brian Pagenkopf (I-2) Synthesis and Properties of New π-

Conjugated Oligomeric, Donor-Acceptor, Photoluminescent and

Electrochemiluminescent Siloles

11:00 Myong Euy Lee (C-1) Recent Results on Silylenoids vs Silylenes

Eric Henderson (C-4) Tailoring the Optical Properties of Group IV

Nanocrystals

11:20 Robert West (C-2) A New Spectroscopy of Silicon and

Germanium Compounds – Muon Spin Resonance

Xiaoming Zhang (C-5) Synthesis and Characterization of Manganese

Doped Silicon Nanoparticles

11:40 Adam Tomasik (C-3) New Monomeric Saturated N-Heterocyclic

Silylenes and Germylenes as Racemic Mixtures

Colin Hessel (C-6) Patterning Sub-100 nm Luminescent Silicon

Nanostructures Derived from Hydrogen Silsesquioxane

12:00 pm Lunch: Harbour Room

1:30 Chair: Kim Baines

*** PLENARY ***

Robert Wolkow (PL-2) Field Regulation of Single Molecule Conductivity by a Charged Atom

7

Time Session A (Ascot) Session B (Balfour)

Chair: Scott McIndoe Chair: Bill Schulz

2:30 Andrey Moiseev (C-7) Direct Detection of Diphenylsilylene and Fast Kinetic Studies of its Reactivity in Solution.

Quantitative Comparisons to Dimethylsilylene

Joerg Glatthaar (C-9) Direct Process of Methyliodosilanes in

Absence of Any Catalyst

2:50 Willie Leigh (C-8) Fast Kinetic Studies of the Reactions of

Transient Silylenes with Alcohols in Fluid Solution

Kenrick Lewis (C-10) Slurry-Phase Direct Synthesis of

Triethoxysilane with Cyanide and Nitrile Promoters

3:10 Coffee Break: Foyer/Chelsea

Chair: Jerry Larson Chair: Barry Arkles

3:30 Masafumi Unno (C-11) Stereochemistry of the Halogenation

of Si-Si Bond

3:50 Carsten Strohmann (C-12) Stereochemistry of Lithiated Silanes

Mark Fink (C-15) Mechanochemical Synthesis of Alkyl-

Passivated Silicon Nanoparticles

4:10 Scott Sieburth (C-13) Silanediol Protease Inhibitors: Advances in

Preparative Methods

Oliver Warschkow (C-16) Water on the Silicon (001) Surface: C-Defects

and Elementary Steps of Surface Oxide Formation

4:30 Kim Baines (C-14) A Comparison of the Reactivity of Brook and

Couret Silenes Toward Alkynes

Brian Korgel (C-17) Solution Synthesis of Silicon Nanowires

4:50 Patrick Steel (I-3) Silenes: Just Heavy Alkenes or New

Strategies for Organic Synthesis?

Jon Veinot (I-4) Hydrogen Silsesquioxane: A Versatile,

Solution Processable Precursor for Silicon Rich Oxides and Freestanding Si-based

Nanocrystals

5:30 Close

8

Saturday, June 2, 2007

Time Session A (Ascot) Session B (Balfour)

Chair: Ken Lewis Chair: Janet Braddock-Wilking

9:00 am François Ganachaud (I-5) Recent Developments in the Synthesis of

Hybrid Fluorinated Silicones

9:40 Paul Zelisko (C-18) Enzyme-Mediated Silicone Chemistry

Sylviane Sabo-Etienne (I-7) The σ-CAM Mechanism: σ-Complexes and

Dynamics and

Robin Perutz (I-6) The σ-CAM Mechanism: Catalysis and

Comparison to Conventional Mechanisms

10:00 Coffee Break: Foyer/Chelsea

Chair: Jorge Cervantes Chair: Don Berry

10:20 Anubhav Saxena (C-19) Narrowly Dispersed Bi-Functional Silicone

Fluid

*** WITHDRAWN ***

Noah Wieder (C-22) Activation of Silicon-Chloride Bonds with

Ruthenium(0) Complexes and Reactivity of Chloro(organosilyl) Ruthenium(II) Complexes

with Acetylene

10:40 David Thompson (C-20) Highly Controlled Assembly of Silicone

Macrostructures

Don Tilley (C-23) Synthesis and Reactivity of Cationic Iridium Silylene Complexes Supported by a PNP

Pincer Ligand

11:00 Yoshimoto Abe (C-21) Synthesis, Structure and Properties of

Silsesquioxanes - Novel Ladder and Cubic Silsesquioxanes

Harald Stüger (C-24) Electronic Interactions in Transition Metal-

Containing Polysilanes

11:20 Joseph Lambert (C-25) Dendritic Calixarene Hosts for Efficient

Binding of Metal Ions

11:40

Yusuke Kawakami (I-8) A Mechanistic Consideration on the

Formation of POSS Derivatives

Leonard Interrante (C-26) Synthesis and Studies of Polycarbosilane-

PMMA Graft Copolymers as Potential Low-K Dielectric Materials

12:00 pm Lunch: Harbour Room

9

Time Session A (Ascot) Session B (Balfour)

Chair: Joyce Corey Chair: Mike Lucarelli

1:30 Reinhold Tacke (C-27) Pentacoordination of Silicon by Five Different Ligand Atoms: Neutral Silicon(IV) Complexes

with an SiXSONC (X = Cl, Br, I) Skeleton

Emmanuel Pouget (C-30) Synthesis of Poly(Dimethylsiloxane) Well

Architectured Block Copolymers in Miniemulsion Using Iodine Transfer

Polymerization

1:50 Tatiana Eliseeva (C-28) Synthesis and Characterization of Imidazole-

Silane Complexes

Chris Bradley (C-31) Synthesis and Catalytic Activity of Titanium

Functionalized Silicone Nanospheres

2:10 Gerardo González-García (C-29)Novel Neutral Hexacoordinate Silicon (IV)

Complexes with -O, N, N- Tridentate and -O, N, N, O- Tetradentate Schiff Base Ligands

De-ann Rollings (C-32) Polysiloxane Nanofibers via Surface Induced

Polymerization of Organotrichlorosilanes

2:30 Coffee Break: Foyer/Chelsea

2:50 Chair: Don Tilley

*** PLENARY ***

Bogdan Marciniec (PL-3) Silicometallics and Catalysis – Application to Synthesis

of Organosilicon Reagents and Polymers

3:50 Not-quite-closing Remarks

4:00 - 6:00

Poster Session: Foyer/Chelsea

6:30 Pre-Banquet Drinks: Harbour Room

7:00 Banquet

10

History of the Silicon Symposium

Bob West kindly supplied us with this account of the history of the Symposium, written in 2004:

In 1967, Makoto Kumada of Kyoto University was chosen as the 6th recipient of the Frederick Stanley Kipping award - the first Japanese scientist ever to win a national award of the American Chemical Society. At the time, It seemed to me that this unique event should be marked in some way. Don Weyenberg of Dow Corning Corporation, sponsors of the award, agreed with this idea, and we began to plan a special organosilicon symposium in Prof. Kumada’s honor.

Because Professor Kumada's Kipping award was to be presented at the spring ACS meeting in Philadelphia, it seemed logical to hold the special organosilicon symposium immediately before the ACS meeting. We therefore approached University of Pennsylvania professor Alan MacDiarmid (Nobel Laureate 2000), who happily agreed to make arrangements to hold the symposium at the University.

That first meeting, which was to become the first Organosilicon Symposium, was enthusiastically received, attracting about 50 participants from industry and academia. A symposium devoted to silicon chemistry was then planned for the following year for Kipping awardee Ulrich Wannagat, in Wisconsin. A tradition had begun.

In the early years, the Organosilicon Symposium was scheduled just before, or just after the spring ACS meeting, usually in the same or a nearby city. By 1982, however, the impact and popularity of the symposia had grown so significantly that this no longer seemed necessary, and since then symposium has been scheduled independently of the ACS meetings. On two occasions, the Organosilicon Symposium was combined with triennial International Organosilicon Symposia: St. Louis (1987), and Guanajuato (2002).*

The organosilicon community in North America was the first to institute yearly organosilicon symposia. These have now served as the model for annual organosilicon meetings in Japan and Korea, as well as the biennial silicon days in Europe.

The organizers of the 2004 symposium in Philadelphia instigated the name change from “Organosilicon Symposium” to “Silicon Symposium”, to better reflect the breadth of silicon chemistry now typically covered by the meeting. We also note that the 2007 Silicon Symposium marks the fourth time this meeting has been held in Canada. Previous meetings were in Windsor (1976), Montreal (1988) and London (1997).

* For reasons that are not immediately apparent, the St. Louis Organosilicon Symposium was not numbered but the Guanajuato Organosilicon Symposium was #35.

11

Past, Present and Future Silicon Symposia # Year Date Site Host Kipping

Awardee 1 1967 Apr 15 Philadelphia, PA A. MacDiarmid (U Pennsylvania) M. Kumada 2 1968 Apr 20 Madison, WI R. West (U. Wisconsin) U. Wannagat 3 1969 Apr 19 Marshall, MN E. Carberry R. Benkeser 4 1970 May 23 Albany, NY J. Zuckerman (SUNY, Albany) R. West 5 1971 Mar 27 Pittsburgh, PA C. Van Dyke (Carnegie Mellon U.) A. MacDiarmid 6 1972 Apr 1 College Park, MD J. Bellama (U. Maryland) D. Seyferth 7 1973 Apr 6 Denton, TX P. Jones (North Texas State U.) A. Brook 8 1974 Mar 29 St. Louis, MO J. Corey (U. Missouri, St Louis) H. Schmidbauer 9 1975 Apr 4 Cleveland, OH M. Kenney (Case Western Reserve U) H. Bock

10 1976 Apr 2 Windsor, ON J. Drake (U. Windsor) M. Lappert 11 1977 Mar 18 Kansas City, MO J. Connolly 12 1978 Mar 10 Ames, IA T. Barton (Iowa State U.) H. Sakurai 13 1979 Mar 30 Ann Arbor, MI M. Curtis (U. Michigan) 14 1980 Mar 28 Fort Worth, TX R. Neilson (Texas Christian U.) E. Ebsworth 15 1981 Mar 27 Durham, NC R. Wells (Duke) 16 1982 Jun 16 Midland, MI C. Frye (Dow Corning) T. Barton 17 1983 Jun 3 Fargo, ND P. Boudjouk (North Dakota State U.) 18 1984 Apr 6 Schenectady, NY R. Shade (GE) R. Corriu 19 1985 Apr 26 Baton Rouge, LA F. Cartledge (Louisiana State U.) 20 1986 Apr 18 Tarrytown, NY B. Kanner (Union Carbide Silicones) P. Gasper – 1987 Jun 7 St Louis, MO P. Gasper, E. Corey, J. Corey

VIII International Organosilicon Symposium

21 1988 Jun 3 Montreal, PQ J. Harrod (McGill U.) R. Calas 22 1989 Apr 7 Philadelphia, PA B. Arkles (Petrarch) 23 1990 Apr 20 Midland, MI T. Lane (Dow Corning) J. Speier 24 1991 Apr 12 E. Paso, TX K. Pannell (U. Texas, El Paso) 25 1992 Apr 2 Los Angeles, CA W. Weber (U. of Southern California) N. Wilberg 26 1993 Mar 26 Indianapolis, IN M. Zeldin 27 1994 Mar 18 Troy, NY J. Rich (GE), J. Crivello (RPI) R. Walsh 28 1995 Mar 30 Gainesville FL PCR, Inc. U. Florida 29 1996 Mar 21 Evanston, IL J. Lambert (Northwestern U.) W. Ando 30 1997 May 30 London, ON K. Baines (U. Western Ontario), M. Brook, W.

Leigh (McMaster U.)

31 1998 May 29 New Orleans, LA M. Fink (Tulane U.), K. Birdwhistell (Loyola U.) J. Lambert 32 1999 Mar 12 Milwaukee, WI C. Recatto (Aldrich), M. Steinmetz (Marquette U.) 33 2000 Apr 7 Saginaw, MI W. Schulz (Dow Corning) P. Jutzi 34 2001 May 4 White Plains, NY K. Lewis, (Crompton Corp.) 35 2002 Aug 25 Guanajuato, MX J. Cervantes (Guanajuato U.) K. Tamao 36 2003 May 30 Akron, OH Claire Tessier, Wiley Youngs (U. Akron) 37 2004 May 21 Philadelphia, PA Don Berry (U. Pennsylvania)

Barry Arkles, Jerry Larson (Gelest) J. Mark

38 2005 Jun 2 Boulder, CO Josef Michl (U. Colorado) 39 2006 May 16 Frankenmuth, MI K. Brandstadt A. Sekiguchi 40 2007 May 31 Victoria, BC L. Rosenberg, S. McIndoe (U. Victoria) 41 2008 ? NY M. Lucarelli (Wacker) ?

12

Upcoming Meetings

5th International Workshop on Silicon-Based Polymers (ISPO'07), June 25-27, 2007, Montpellier, France.

http://www.enscm.fr/ispo2007.htm

The 4th European Silicon Days, September 9-11, 2007, Bath, UK. http://www.mmsconferencing.com/eod/organosilicon.php

The 15th International Symposium on Organosilicon Chemistry (ISOSXV), June 1-6, 2008, Jeju, Korea. For more information, see next page.

http://www.isos-xv.org/

13

The 15th International Symposium on Organosilicon Chemistry

June 1~6, 2008 Hotel Lotte in Jeju, Korea

INVITATION On behalf of the organizing committee of the 15th International Symposium on Organosilicon Chemistry (ISOS-XV), we are very pleased to invite you to ISOS-XV being held at Jeju, Korea in 2008. ISOS has been taking place every 3 year since the 1st ISOS had been held at Prague (Czechoslovakia) in 1965. The aim of the meeting is to provide the major opportunity to keep up-to-date on the latest research results and technological developments in the field of organosilicon chemistry. It is also with no doubt that the symposium will be an invaluable chance for participants to make a great network with professionals and distinguished leaders from around the world. Especially, ISOS-XV will be jointly held with the 2nd Asian Silicon Symposium (ASiS) and 13th Symposium of the Society of Silicon Chemistry, Japan. In 2008, the scientific program with the main theme of "Living World of Silicon Chemistry: Centennial Revisit, Evolution, and Renaissance" will be planned to cover the wide field of organosilicon chemistry. Jeju Island features breathtaking sceneries, amiable people, and unique historical and cultural heritage. Unforgettable experiences will be waiting for you. The organizing committee will do beyond our best to make this symposium into a wonderful meeting. We cordially invite you to Jeju, Korea in 2008. Myong Euy Lee Chairman Organizing Committee of ISOS-XV THEME Living World of Silicon Chemistry : Centennial Revisit, Evolution, and Renaissance TOPIC The scientific program will be composed of plenary lectures, invited lectures, oral talks, and poster presentations which belong to all areas of silicon-based science and technology. The conference will include the following topics: - New Compounds and New Reactions in Silicon Chemistry - Silicon-Transition Metal Chemistry - Photochemistry and Gas-phase Chemistry of Organosilicon Compounds - Physicochemical and Theoretical Aspects of Silicon Chemistry - Catalysis and Synthesis in Organosilicon Chemistry - Hyper-valent Compounds in Silicon Chemistry - Reactive Intermediates and Multiply-bonded Silicon Species - Silicon in Organic Synthesis - Sol-Gel Chemistry: Silanols, Silsesquioxanes, Polysiloxanes and Related Materials - Synthesis and Processing of Silicon-based Polymers - Nanomaterials and Supramolecules Containing Silicon - Silicon-based Precursors for Ceramic and Electronic Materials - Biological, Medicinal and Environmental Aspects of Silicon Chemistry - Functionalization of Silicon Surfaces - Silicon in Paints, Coatings, Energy and the Other Industrial Applications - Industrial Aspects of Silica and Silicates REGISTRATION On-line registration and credit card payments will be available at http://www.isos-xv.org. You can register from October, 2007. - Deadline of Pre-Registration April 30, 2008 ABSTRACT SUBMISSION Authors are invited to submit abstracts on-line only from October 2007. - Deadline of Abstracts Submission February 29, 2008 ISOS-XV Secretariat 1st Floor, Haeoreum Bldg., 748-5 Yocksam-dong, Kangnam-ku, Seoul 135-925, Korea Tel: +82-2-566-6067 | Fax: +82-2-566-6087 | E-mail: isos@isos-xv.org

14

Alan G. MacDiarmid

1927 – 2007

“Since silicon lies immediately below carbon in the periodic table…”*

Dr. Alan G. MacDiamid may be best known to newer members of the community as a co-recipient of the 2000 Nobel Prize in Chemistry for his work in the field of conducting polymers, but fully half of his academic life was spent as in the fields of inorganic and silicon chemistry. Alan hosted the inaugural Organosilicon Symposium in 1967, in honor of his friend and F. S. Kipping Awardee M. Kumada, and was himself the recipient of the 1971 Kipping Award.

Born in Masterton, New Zealand, Alan earned his B.Sc. and and M.Sc. from the University of New Zealand, then moved abroad under the auspices of a Fulbright Fellowship. Alan traveled first to the University of Wisconsin where he earned his Ph.D. in 1953 studying the photo- and electrochemistry of cyanide complexes with N. F. Hall. Alan received his introduction to silicon chemistry – and a second Ph.D. – at Cambridge in 1955, under H. J. Emeleus.

Alan joined the University of Pennsylvania in 1955, and remained an active member of the Chemistry Department until his death on February 7, 2007. Alan published over 600 research papers and held over two dozen patents. He received numerous honors and awards in addition to the Kipping and Nobel, including being elected to the National Academy of Science and as a Fellow of the Royal Society of London.

Beyond his honors and accomplishments, those who experienced one of his research seminars - replete with demonstrations and exhortations - will remember an enthusiastic scientist who always found joy in discovering something new or unexpected. Those of us fortunate to have known Alan personally will miss a friend and colleague of enormous charm and an unfailing sense of humor.

Don Berry (May, 2007) * quote invariably used by A.G.M. to open a lecture or seminar on silicon chemistry, recorded by his students and displayed on a prominent plaque in his office until 2007.

15

PLENARY

LECTURE

ABSTRACTS

EFFICIENT CONVERSION OF ELECTRICAL ENERGY INTO LIGHT USING SILOLES AND SPIROSILABIFLUORENES

Zakya H. Kafafi

Naval Research Laboratory, Washington D.C. 20375, USA. Tel: 202-767-9529; Fax: 202-404-8114;E-mail: kafafi@nrl.navy.mil

Significant progress has been made in developing organic light-emitting and carrier transport materials with enhanced optical and electronic properties for flat panel displays, solid state lighting and lasing. Designing molecules using a building block based on a silacyclopentadiene (silole) ring led to the development of highly efficient solid state emitters1 and superior electron transporters.2 Electroluminescence quantum efficiencies (ratio of photons generated per electrons injected) close to the theoretical limit have been achieved for organic light-emitting diodes (OLEDs) based on silole derivatives.1

A new class of electroactive silole derivatives, namely spirosilabifluorenes, has been recently synthesized and characterized.3,4 These novel spiro-linked silafluorenes form transparent and stable amorphous films with relatively high glass transition temperatures (Tg >200 oC). Their absorbance spectra show a significant bathochromic shift relative to that of the corresponding carbon analogue as a result of the effective σ*-π* conjugation between the σ* orbital of the exocyclic Si-C bond and the π* orbital of the oligoarylene fragment. Solid-state films exhibit intense violet-blue emission.

The talk will give an overview of the work carried out at NRL related to this class of molecules. Different approaches taken for tuning their electronic structures for good carrier transport and high fluorescence efficiency through molecular engineering, and optimizing device performances via electronically tailored organic/metal and organic/organic interfaces will be discussed.

_________________________________ 1L. C. Palilis, H. Murata, A. J. Mäkinen, M. Uchida, and Z. H. Kafafi, Organic

Electronics (Invited), 4, 113 (2003). 2L. C. Palilis, M. Uchida, and Z. H. Kafafi, IEEE J. Quantum Electronics (Invited), 10,

79 (2004). 3S.H. Lee and Z. H. Kafafi, J. Am. Chem. Soc. 127, 9071 (2005). 4 I. L. Karle, R. Butcher, M. A. Wolak, S. H. Lee, and Z. H. Kafafi, J. Chem. Cryst. 37, 171 (2007).

PL - 1

FIELD REGULATION OF SINGLE MOLECULE CONDUCTIVITY BY A CHARGED ATOM Robert A. Wolkow Department of Physics, University of Alberta, and National Institute for Nanotechnology, National Research Council of Canada A new concept for a single molecule transistor is demonstrated [1]. A single chargeable atom adjacent to a molecule shifts molecular energy levels into alignment with electrode levels, thereby gating current through the molecule. Seemingly paradoxically, the silicon substrate to which the molecule is covalently attached provides 2, not 1, effective contacts to the molecule. This is achieved because the single charged silicon atom is at a substantially different potential than the remainder of the substrate. Charge localization at one dangling bond is ensured by covalently capping all other surface atoms. Dopant level control and local Fermi level control can change the charge state of that atom. The same configuration is shown to be an effective transducer to an electrical signal of a single molecule detection event. Because the charged atom induced shifting results in conductivity changes of substantial magnitude, these effects are easily observed at room temperature. [1] Paul G. Piva1,Gino A. DiLabio, Jason L. Pitters, Janik Zikovsky, Moh’d Rezeq, Stanislav Dogel, Werner A. Hofer & Robert A. Wolkow, Field regulation of single-molecule conductivity by a charged surface atom, NATURE 435, 658-661 (2005)

PL - 2

SILICOMETALLICS AND CATALYSIS – APPLICATION TO SYNTHESIS OF UNSATURATED ORGANOSILICON REAGENTS AND POLYMERS Bogdan Marciniec Department of Organometallic Chemistry, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznań, Poland

While organometallics play a fundamental role in catalysis of organic compounds, the reactivity of species involving a transition metal (TM)-silicon bond (silicometallics) is a key point in most conversions of silicon derivatives catalyzed by metal complexes such as hydrosilylation, dehydrogenative silylation, double silylation and others (for recent review see1).

We have developed a new type of TM catalyzed reaction of vinyl-substituted organosilicon compounds with a variety of olefins called “silylative coupling” (SC) or “trans-silylation”, which takes place in the presence of complexes containing or generating M-H and M-Si bonds (for recent review see2). SC of olefins has been recently extended to catalytic activation by vinylsilanes of ≡C-H3, =Caryl-H

4 as well as by OH of alcohols5 and of silanols6 indicating a new general role of vinylsilicon compound as a silylative agent and a hydrogen acceptor.

In the lecture we present an application of SC vs. metathesis of olefins, dienes and acetylenes to synthesis of variety of linear and cyclic organosilicon compounds as well as silicon-based π-conjugated organic polymers, which are very useful intermediates in organic synthesis and as precursors for luminescent materials respectively. The results of silylation by vinylsilanes supported by equimolar reaction of M-Si (where M = Ru, Rh, Ir) with substrates (E-H) allows us to propose a general scheme of catalysis proceeding via insertion of vinylsilicon compounds into M-H bond and β-Si transfer to the metal with elimination of ethylene to generate M-Si species intermediate (silicometallics) followed by an insertion of olefins, acetylenes and other substrates into M-Si bond and β-H transfer to the metal with elimination of respective substituted silicon compounds.

[M] H +

E = CHM = Ru, Rh, Ir;

+ E H

RO ,, , R3SiO

Si[M]Si

+ [ M] H

+

where

Si[M] Si EC

1 B.Marciniec, in Applied Homogeneous Catalysis with Organometallic Compounds,

2nd Compl. Revised and Enlarged Edition, B.Cornils & W.Herrman eds, Wiley-VCH, Weinheim, Vl,pp. 491-512 (2002).

2 B.Marciniec, Coord. Chem.Revs, 2005, 249, 2374. 3 B.Marciniec, B.Dudziec, I.Kownacki, Angew Chem., Int.Ed., 2006, 45, 8180. 4 F.Kakiuchi, M.Matsumoto, M.Sonoda, T.Fukuyama, N.Chatani, S.Murai, Chem.Lett., 2000, 29, 750. 5 J.W.Park, H.J.Chang, C.H.Jun, Synlett, 2006, 771. 6 B.Marciniec, P.Pawluc (unpublished results).

PL - 3

INVITED

LECTURE

ABSTRACTS

SILICON−SILICON π SINGLE BOND Soichiro Kyushin

Department of Chemistry and Chemical Biology, Graduate School of Engineering, Gunma University, Kiryu, Gunma 376-8515, Japan

Silicon−silicon bonds have been classified into the single bond, double bond, and triple bond. Silicon−silicon single bonds are normally σ bonds which are formed by the combination of two sp3 silicon atoms. I report herein a novel silicon−silicon π single bond. This silicon−silicon π single bond is formed by the combination of two sp2 silicon atoms, but it is not accompanied by a σ bond in contrast with a carbon−carbon π bond. The concept of the silicon−silicon π single bond is described as follows.

+Si Si Si Si

+ CC C C

silicon−silicon π single bond

carbon−carbon π bond

3p 3p

2p 2p

π

π

σ

The silicon−silicon π single bond has been found in 1,2,2,3,4,4-hexa-tert-

butylbicyclo[1.1.0]tetrasilane (1). The X-ray crystallography showed that the two bridgehead silicon atoms have the planar structure and the distance between them is 2.856 Å. The ESR spectra, magnetic susceptibility, 29Si NMR, and theoretical calculations of 1 showed that the electrons in the 3p orbitals of the two bridgehead silicon atoms are paired to form a silicon−silicon π single bond (Figure 1). Details of the structural features and properties of the silicon−silicon π single bond are explained.

SiSi

SiSi

t-Bu

t-Bu

t-But-Bu

t-But-Bu

1

Figure 1. The HOMO of 1 calculated at the B3LYP/6-31G* level.

I - 1

SYNTHESIS AND PROPERTIES OF NEW PI-CONJUGATED OLIGOMERIC, DONOR-ACCEPTOR, PHOTOLUMINESCENT AND ELECTROCHEMILUMINESCENT SILOLES Brian L. Pagenkopf

The University of Western Ontario, Department of Chemistry, 1151 Richmond Street, London, Ontario, N6A 1Y2 Canada

Using the reductive cyclization of diethynylsilanes by lithium naphthylenide as a core synthetic strategy several new siloles have been prepared, including a non-symmetrical 2-chloro-5-iodosilole that has enabled the exploration of oligomeric siloles that established the effective conjugation length for related polymers, a family of donor-acceptor siloles that show the longest wavelength photoluminescence emission ever reported for a silole, and 3,4-disubstituted siloles with unusually high quantum efficiencies. Additionally, the electrochemiluminesence of some thiophene-silole hybrids will be described.

SiR2

PhPh

I ClSiR2

Ph Ph • Oligomeric Siloles• Donor-Acceptor Siloles• Siloles with High Photoluminescent Quantum Efficiencies• Electrochemiluminescent Siloles

I - 2

SILENES: JUST HEAVY ALKENES OR NEW STRATEGIES FOR ORGANIC SYNTHESIS?

P. G. Steel

Department of Chemistry, University of Durham, Science Laboratories, South Road, Durham, DH1 3LE UK. p.g.steel@durham.ac.uk

Although evidence for the existence of silenes was first reported in 1967, there have been minimal efforts at exploiting the unique reactivity of these species in organic synthesis. We have been exploring this area through the generation and capture of silenes with various silenophiles.1 These provide access to highly functional silanes which have considerable potential for new synthetic strategies.2 For example, silenes 1, generated through a modified Peterson reaction, undergo an in situ Diels Alder cycloadditions to afford silacyclohexenes 2 with high diastereoselectivity. These cycloadducts are cyclic allyl silanes that on reaction with electrophiles retain the silicon within the product structure for further transformations. Consequently these represent versatile bifunctional reagents for silicon directed organic synthesis.3 In this presentation details of these transformations and studies with other silenes and silenophiles will be discussed.

O

R H

H

R SiSiMe3

Ph

Si

R1

R

SiMe3

Ph

R1

i. Ph(Me3Si)2SiMgBr

ii. BuLi, LiBr

1

2

4 3

O

OO

Ar

OH

O

O

O

R1

RHO

- 40ÞC

1. M. B. Berry, R. J. Griffiths, M. Sanganee, P. G. Steel and D. K. Whelligan, Org. Biomol. Chem., 2004, 2, 2381-2392

2. M. Sanganee, P. G. Steel and D. K. Whelligan, Org. Biomol. Chem., 2004, 2, 2393-2402.

3. J. D. Sellars and P. G. Steel, Org. Biomol. Chem., 2006, 4, 3223 – 3224; J. D. Sellars, P. G. Steel and M. J. Turner, Chem Commun., 2006, 2385-2387.

I - 3

"HYDROGEN SILSESQUIOXANE: A VERSATILE, SOLUTION PROCESSABLE PRECURSOR FOR SILICON RICH OXIDES AND FREESTANDING Si-BASED NANOCRYSTALS" Jonathan G. C. Veinot

Department of Chemistry, University of Alberta, Edmonton, AB., Canada, T6G 2G2 Semiconductor nanoparticles are of great scientific and technological interest partly because of their unique electronic, optical, and chemical characteristics. Silicon particles of sub-5 nm dimension are particularly intriguing because of their intense photoluminescent response and the promise of linking silicon photonics with electronics. To facilitate a more complete understanding of Si-nanoparticle properties, as well as the realization of practical nanoparticle-based devices, reproducible methods for preparing tangible quantities of material must be developed. In addition to scalability, any ideal preparative method must afford materials with well-defined size, shape, crystal structure, and surface chemistry while also offering convenient particle patterning/ordering. Recently, our group has established a straightforward method for preparing silicon nanoparticles from hydrogen silsesquioxane.1 This presentation will be a detailed discussion outlining the versatility of our synthetic methodology, spectroscopic investigation of particle formation and growth, crystal structure control, particle liberation, as well as nanoparticle composite patterning.

_________________________________

1 C. M. Hessel, E. J. Henderson, J.G.C. Veinot Chem. Mat., 2006, 18, 6139-6146.

I - 4

RECENT DEVELOPMENTS IN THE SYNTHESIS OF HYBRID FLUORINATED SILICONES

Claire Longuet, Amédée Ratsihimety, Francine Guida-Pietrasanta, François Ganachaud,

Bernard Boutevin Institut Charles Gerhardt UMR5253 CNRS/UM2/ENSCM/UM1, Ingénierie et

Architectures Moléculaires, Ecole Nationale Supérieure de Chimie de Montpellier, 8 Rue de l’Ecole Normale 34296 Montpellier cedex, France

The synthesis of multiblock silicone copolymers, made of alternated perfluorinated alkyl chains and dimethylsiloxane oligomers, has been studied in our laboratory for the last 20 years, on the impulsion of Dow Corning and Daikin, respectively. The materials resulting from blending and crosslinking these polymers are high tech elastomers, which specifications are sufficient elasticity and solvent resistance in a wide range of temperature, typically between -80 to 350°C. Recent developments in our laboratory focused on the chemistry and physico-chemistry of these polymers, in order to improve the average molar masses which are generally too low to prepare materials with good mechanical properties. This presentation is divided in four parts. First, a quick literature survey comparing the surface and mechanical properties, as well as the solvent and temperature resistances, of conventional fluorosilicone (e.g. Silastic) and hybrid fluorosilicones will be given. Second, we will report on the side reactions occurring while carrying out the polyhydrosilylation of conventional dihydridosilanes and divinyl perfluorinated molecules. We have made benefit of such unexpected grafting reactions to prepare slightly fluorinated silicone elastomers, starting from conventional PDMS. Third, we observed that some tailored fluoroalkyl chains end-capped by silicone knees lead upon solvent removal to an apparent cross-link material. The self-assembly of some of the hybrid silicone blocks into physical “knots” of lamellar phases was confirmed by AFM, TEM and DSC analyses. Finally, an original polycondensation process of perfluorinated bricks conventionally prepared in the laboratory, using a B(C6F5)3 catalyst, will be described. The characterization of thus-prepared polymers by SEC3 showed the generation of « dead » macrocycles responsible for the limiting molar masses observed systematically.

I - 5

THE σ-CAM MECHANISM: CATALYSIS AND COMPARISON TO CONVENTIONAL MECHANISMS Robin N. Perutza and Sylviane Sabo-Etienneb

a Department of Chemistry, University of York, York YO10 5DD, UK b Laboratoire de Chimie de Coordination du CNRS, 205 Route de Narbonne, 31077 Toulouse Cedex 04, France.

The σ-CAM mechanism, introduced in the previous presentation by S. Sabo-Etienne, provides a pathway for metathesis of metal-element bonds (element E = H, C, Si, and B). At its core lies the interchange of σ-ligands, a process that is often observed through the fluxional behavior of σ-complexes. In this presentation, we show that catalytic cycles may be constructed with the aid of the σ-CAM mechanism for hydrosilation of alkenes (Scheme 1), hydrogenation of alkenes, borylation of alkanes and isotopic exchange events. These cycles operate at constant oxidation state and depend on the accessibility of σ-complexes. Some of them are already supported by DFT calculations. We compare these cycles to conventional routes involving oxidative addition-reductive elimination or σ-bond metathesis.

Scheme 1. A σ-CAM mechanism for hydrosilation

_________________________________

1 Perutz, R. N., Sabo-Etienne, S. Angew. Chem. Int. Ed. 2007, 46, 2578-2592.

I - 6

THE σ -CAM MECHANISM: σ -COMPLEXES AND DYNAMICS Sylviane Sabo-Etiennea and Robin Perutzb

a Laboratoire de Chimie de Coordination du CNRS, 205 Route de Narbonne, 31077 Toulouse Cedex 04, France. b Department of Chemistry, University of York, York YO10 5DD,UK

During this symposium two lectures will concern the description of a new concept, the σ-CAM mechanism, which can be applied to the functionalization of various substrates and especially to silane compounds. The first lecture presented by S. Sabo-Etienne introduces this concept and presents an overview of literature X-ray, DFT and NMR studies that provide the foundation of the mechanism.

In σ-complexes, a σ-bond E−H acts as donor to a transition metal. The phenomenon is established for dihydrogen, silane, borane and alkane ligands (E = H, Si, B, C). When a complex contains a hydride ligand and one or two σ-ligands, dynamic exchange can occur between hydride and E−H hydrogens without change in oxidation state. Such exchange processes are especially well established for dihydrogen(hydride) complexes and for silane(hydride) complexes. This exchange step can be combined with coordination of E−H and ultimate release of E'−H (E ≠ E') to complete a metathesis sequence which we term σ-CAM or σ-Complex Assisted Metathesis.1 Examples involving particular Si-compounds will be more specifically discussed, including the most recent unpublished data concerning chlorosilane activation.

In the second part, presented by R. Perutz, a comparison with conventional mechanisms will be analyzed and the use of such a concept will be adapted to various catalytic reactions.

[M]H

H

SiR3

[M]H

[M]SiR3

HH [M]+ HSiR3

σ-CAM+ H2

SiR3

σ-CAM

[M]E

[M] + H-EE'

[M]E

H

E'

[M]E'

EH

+ H-E'

_________________________________

1 Perutz, R. N., Sabo-Etienne, S. Angew. Chem. Int. Ed. 2007, 46, 2578-2592.

I - 7

A MECHANISTIC CONSIDERATION ON THE FORMATION OF POSS DERIVATIVES

Yusuke KAWAKAMI

School of Materials Science, Japan Advanced Institute of Science and Technology

Asahidai 1-1, Nomi, Ishikawa 9231292 Japan: kawakami@jaist.ac.jp

Although, completely condensed “cubic” octameric silsesquioxane, [POSS, (RSiO1.5)8, T8] has been paid a lot of attention by many researchers [1], they are not always convenient for further Functionalization, or applications. Some functional groups are desired for the practical use. The products in the hydrolysis of tri-functional silane compounds depend on the reaction conditions, such as concentration of the compound, amount of water, temperature, reaction time, etc.

By changing the reaction conditions, even incompletely condensed products can be obtained, which will find high applicability in designing new nano-composite materials. Under basic condition with Si : Na ratio; 2 : 1, incompletely condensed Si-7 triol derivative, whose MS and NMR are shown in Figure 1, was firstly formed, and converted into Si-8 compound. This Si-8 compound was elucidated as so-called double decker silsesquioxane by its MS and NMR as shown in Figure 2. When cubic T8 was treated with sodium hydroxide in an alcohol, T7 and double decker silsesquioxane were produced. When the double decker silsesquioxane was treated with an acid, it was converted into completely condensed T8. Some higher condensed products were also seen. These compounds are inter-convertible under suitable condition.

In any cases, formation of cyclic tetramer seems essential to give higher condensed products. In many cases, the selectivity of the formation of the cis isomer is very high. This might be caused by template effect of sodium ion.

Figure 1. Product after 15 hr stirring Figure 2. Product after 40 hr

References

1. (a) C. Pakjamsai, Y. Kawakami, Polym J. 36, 455 (2004). (b) C. Pakjamsai, N. Kobayashi, M. Koyano, S. Sasaki, Y. Kawakami, J. Polym. Sci., Part A: Polym. Chem. 42, 4587 (2004). (c) C. Pakjamsai, Y. Kawakami, Design. Monom. Polym. 8, 423(2005). (d) D. W. Lee, Y. Kawakami, Polymer J., in press.

Stirring for 40h at r.t

I - 8

CONTRIBUTED

LECTURE

ABSTRACTS

RECENT RESULTS ON SILYLENOIDS VS SILYLENES Myong Euy Lee, Young Mook Lim, Ha Jin Jeong and Jee Min Ryu

Department of Chemistry & Medical Chemistry, College of Science and Technology,Yonsei University, Wonju, Gangwondo, 220-710, Korea

Silylenoid, corresponding to carbenoid in organic chemistry has been postulated as

key intermediate in the reduction of dihalosilanes to synthesize silylenes or polysilanes. Recently we have synthesized the stable functional halosilylenoids, (Tsi)X2SiLi (Tsi = trisyl = C(SiMe3)3, X = Br, Cl), at room temperature from the reduction of (Tsi)SiX3 with lithium naphthalenide (LiNp) or C8K. The reaction of (Tsi)Br2SiLi with MesMgBr at -10 oC gave lithium mesitylsilylenoid as a complex with magnesium bromide which was transmetalated by MgBr2 at THF reflux temperature to give magnesium mesitylsilylenoid as a LiBr complex. This new species was stable up to 65 oC. This is the first stable magnesium silylenoid, and methodologically the first case of the formation of the metallosilylenoid from the metallosilylenoid through a transmetalation reaction.

Further reduction of (Tsi)bromosilylenoid using 4.2 equiv of LiNp diluted in THF gave (Tsi)bromodilithiosilane in high yield, which was stable in the condensed phase at room temperature and at even THF reflux temperature. This result implies that (Tsi)tribromosilane is initially reduced with 2 equiv of LiNp to lead to the corresponding (Tsi)bromosilylenoid and then is further reduced by another 2 equiv of LiNp leading to (Tsi)bromodilithiosilane.

In this presentation, the results mentioned above and their reactivities will be

presented in detail, and also discussed on acyclic silylenes and silylenoids having tetrakis(trimethysilyl)cyclohexenyl (Ttc ) substituents.

C - 1

A NEW SPECTROSCOPY OF SILICON AND GERMANIUM COMPOUNDS – MUON SPIN RESONANCE Robert West , Nicholas J. Hill, Adam C. Tomasik Organosilicon Research Center, University of Wisconsin, Madison WI 53706 USA Paul W. Percival, Brett C. McCollum, Jean-Claude Brodovitch, Jason A. C. Clyburne Department of Chemistry, Simon Fraser University, Burnaby BC Canada V5A 1S6 The TRIUMF cyclotron at the University of British Columbia generates the world’s most intense beam of mu mesons (muons), which capture electrons to form muonium atoms (Mu.). The latter can react with unsaturated molecules to give muoniated radicals. The muons decay with t1/2 = 2.2 microseconds, producing positrons, which can be individually counted. When this experiment is carried out in a magnetic field, structural information can be obtained for the muon-containing molecules. This is muon spin resonance, µSR.1,2 In this paper we report the first examples of muonium capture by silicon and germanium compounds. The stable N-heterocyclic silylenes, 1 and 2, and the germylene, 3, are shown as their muonium adducts. Also shown are the hyperfine splitting constants for these molecules determined by µSR. The muoniated germylene exhibits the largest muon hyperfine splitting ever observed for any molecule. The significance of these findings will be discussed and additional µSR data will be presented.

NSi

N

tBu

tBu

. Mu

NSi

N

tBu

tBu

. Mu

NGe

N

tBu

tBu

. Mu

hfcc,MHz

154.9 235.4 649.3

1 I. McKenzie, J-C. Brodovich, P. W. Percival, T. Ramnial, J. A. C. Clyburne, J. Am. Chem. Soc., 2003, 125, 11565. 2 C. J. Rhodes, J. Chem. Soc., Perkin Trans., 2002, 2, 1379.

C - 2

NEW MONOMERIC SATURATED N-HETEROCYCLIC SILYLENES AND GERMYLENES AS RACEMIC MIXTURES Adam C. Tomasik, Wenjian Li, Nicholas J. Hill, Amitabha Mitra, Galina Bikzhanova, Robert West. Organosilicon Research Center at the University of Wisconsin – Madison, 1101 University Avenue, Madison, WI 53706 This presentation discusses recent progress in the field of low-valent N-heterocyclic compounds containing Si or Ge. Stable silylenes, rac-N,N'-di-(tert-butyl)ethylene-4,5-dimethyl-1,3-diaza-2-silacyclopentane-2-ylide (I)1 and rac-N,N'-di-(tert-butyl)ethylene-4-(tert-butyl)-1,3-diaza-2-silacyclopentane-2-ylide (II) are synthesized by the reaction of their corresponding dibromides with potassium graphite. Unlike the analogous unsubstituted saturated silylene, which tetramerizes in concentrated solution or as a solid, the new silylenes show no tendency to oligomerize. Instead, they persist as stable colorless liquids. Additionally, two new stable germylenes, rac-N,N'-di-(tert-butyl)ethylene-4,5-dimethyl-1,3-diaza-2-germacyclopentane-2-ylide (III) and rac-N,N'-di-(tert-butyl)ethylene-4-(tert-butyl)-1,3-diaza-2-germacyclopentane-2-ylide (IV) are isolated as liquids by the reaction of their corresponding dichlorides with lithium metal. Reactivity of the silylenes and progress towards resolving the enantiomeric product mixtures will also be discussed.

1 Li, W.; Hill, N. J.; Tomasik, A. C.; Bikzhanova, G. A.; West R. Organometallics 2006, 25, 3802.

C - 3

Tailoring the Optical Properties of Group IV Nanocrystals

Henderson, E.J., Veinot, J. G. C. The optical properties exhibited by Group IV semiconductor nanocrystals make these materials particularly appealing for many applications. It is well know that silicon and germanium nanocrystals exhibit size-dependent photoluminescence (PL) which can be tuned throughout the infrared and visible spectrum. An alternative approach to tunable PL involves modifications to the nanocrystal composition, specifically through alloying and crystal doping. Our research group has recently developed a method for preparing oxide-embedded Group IV semiconductor nanocrystals such as Si, Ge, alloys of these elements, boron-doped Si, as well as metallic Sn nanocrystals. The present contribution will outline the synthesis, composition, and size-dependent PL response of these materials.

C - 4

SYNTHESIS AND CHARACTERIZATION OF MANGANESE DOPED SILICON NANOPARTICLES

Xiaoming Zhang,1 Angelique Y. Louie,1 and Susan M. Kauzlarich2 1Department of Biomedical Engineering, University of California, Davis, CA 95616

2Department of Chemistry, University of California, Davis, CA 95616 Multifunctional nanomaterials are becoming increasingly important because such nanomaterials provide the possibility for enhanced functionality and multiple properties in contrast to their single-component counterparts. In this study, manganese doped silicon nanoparticles were synthesized and their magnetic and photoluminescence (PL) characteristics were studied. The PL intensity peak for the magnetic Si nanoparticles was found to be red-shifted compared with that for the undoped Si nanoparticles. Such magnetic silicon nanoparticles displayed strong photoluminescence in the green region of the visible spectrum with a 16% quantum yield. EPR measurement and PL dynamics study show that Mn ions be distributed in Si nanoparticles. This material represents a nontoxic imaging probe that would combine the strengths of both MRI, through the paramagnetic Mn ion, and optical imaging technologies, through the Si nanoparticles.

C - 5

PATTERNING SUB-100 NM LUMINESCENT SILICON NANOSTRUCTURES

DERIVED FROM HYDROGEN SILSESQUIOXANE

Colin Hessel

Department of Chemistry, University of Alberta, Edmonton, AB., Canada, T6G 2G2

The ability to precisely pattern oxide-embedded silicon nanocrystals has become a

crucial requirement for the development of silicon nanocrystal-based flash memory

devices and optical waveguides. With this objective in mind, we have developed a

method to produce sub – 100 nm patterns of oxide-embedded silicon nanocrystals using

electron beam lithography and hydrogen silsesquioxane (HSQ). Typically used as a

dielectric insulator, HSQ is a common negative-type resist used routinely in micro and

nanofabrication. Using conventional electron beam lithography and known developing

procedures, we have produced various sub – 100 nm three-dimensional structures of

HSQ on semiconductor surfaces. These patterns have been subsequently processed

using methods developed in our laboratory to yield luminescent, oxide-embedded

silicon nanocrystals. These patterned silicon nanostructures have been characterized by

optical microscopy, scanning electron microscopy (SEM), transmission electron

microscopy (TEM) and photoluminescence spectroscopy (PL). This method exploits the

well-established science surrounding HSQ, and adds to the breadth of its versatility.

The production, application potential and characterization of these silicon nanostructures

will be discussed.

C - 6

DIRECT DETECTION OF DIPHENYLSILYLENE AND FAST KINETIC STUDIES OF ITS REACTIVITY IN SOLUTION.

QUANTITATIVE COMPARISONS TO DIMETHYLSILYLENE.

Andrey G. Moiseev and William J. Leigh*

Department of Chemistry, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4M1

Steady state photolysis of 1,1,3,3-tetramethyl-2,2-diphenyl-1,2,3-

trisilacyclohexane (1) in hexane solution produces diphenylsilylene (SiPh2) and 1,1,2,2-tetramethyl-1,2-disilacyclopentane (2) in nearly quantitative yield, as shown by the results of trapping experiments with methanol. Laser flash photolysis of 1 in hexane allows the direct detection of SiPh2 (λmax = 290, 515 nm), which decays on the microsecond time scale with the concomitant growth of a second species, assigned to tetraphenyldisilene (3; λmax = 290, 370, 460 nm) on the basis of its spectrum and kinetic behavior. Absolute rate constants for reaction of SiPh2 with a variety of representative substrates have been measured, providing a comprehensive quantitative picture of the reactivity of the species toward oxygen, O-H and M-H (M = Si, Ge, Sn) insertions, addition to C=C, C=O, and C≡C multiple bonds, chlorine atom abstraction, and Lewis acid-base complexation with ethers. Analogous data have also been obtained for reaction of the same substrates with dimethylsilylene (SiMe2), generated by laser flash photolysis of dodecamethylsilacyclohexane under the same conditions, to allow quantitative comparisons of reactivity as a function of substitution at silicon.

C - 7

FAST KINETIC STUDIES OF THE REACTIONS OF TRANSIENT SILYLENES WITH ALCOHOLS IN FLUID SOLUTION

Andrey G. Moiseev and William J. Leigh

Department of Chemistry, McMaster University 1280 Main Street West, Hamilton, ON Canada L8S 4M1

One of the best known reactions of transient silylene derivatives is the O-H insertion reaction with alcohols, and detailed mechanistic studies of the process in the gas phase, in solution, and in low temperature matrixes were published throughout the 1980s by a number of groups. The mechanism of the reaction in condensed phases has been shown to involve initial Lewis acid-base complexation of the silylene with the alcohol, followed by rate-determining proton transfer from oxygen to silicon, through the elegant low temperature spectroscopic studies of Gillette, Noren and West on the reactions of aliphatic alcohols with transient mesityl-substituted silylenes at ca. 80K.

In this talk we present the results of our recent studies of the reactions of simple alcohols with dimethyl- and diphenylsilylene in solution at room temperature, in which the process is followed on the nanosecond time scale by direct detection of both the silylenes and their complexes with methanol and tert-butanol. Our results indicate that the mechanism of West and coworkers is indeed quite general, but show that the proton transfer step within the initially formed complex proceeds exclusively via a catalytic pathway involving a second molecule of alcohol acting as a proton shuttle. This process is quite fast, proceeding at rates within a factor of 10 of the diffusion limit in these particular silylene-alcohol systems, yet it exhibits surprisingly large deuterium kinetic isotope effects – up to kH/kD ~ 12 depending on the silylene and the alcohol.

R2Si: + R'OHk1

Si:

R'OH

R2

k2[R'OH]SiOR'

R2 H

C - 8

DIRECT PROCESS OF METHYLIODOSILANES IN ABSENCE OF ANY CATALYST Günther Maier, Jörg Glatthaar Department of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 58, 35392 Giessen, Germany joerg.glatthaar@org.chemie.uni-giessen.de The direct reaction1 of elementary silicon with methyl chloride, independently developed by Rochow2 and Müller,3 is the most important entry to the synthesis of silicones. Usually a mixture of silicon and a catalytic additive, the so-called contact mass, is reacted at 250 – 350 oC with gaseous methyl chloride. Complex product mixtures, consisting mainly of dimethyldichlorosilane (80-90%), are achieved. In this report we present a new access to dimethylsilicones via dimethyldiiodosilane, which avoids the usage of extra catalytically active components. In our previous matrix isolation spectroscopy study4 we have demonstrated that silicon atoms react with methyl halides to dimethyldihalosilanes upon irradiation. When using methyl iodide, the silylene - methyl iodide adduct 1 , which is directly formed during

co-deposition of silicon atoms and pure methyl iodide at 10 K, was found to be stable upon annealing to 80 K. More important, if the co-condensation was conducted at that temperature, some dimethyldiiodosilane 2 was immediately formed. This was the first observation of a direct reaction of silicon proceeding in the absence of any catalyst. Next we have designed a new co-deposition apparatus in order to expand these qualitative matrix isolation studies to a more preparative scale allowing the isolation and identification of the products by standard procedures.5 By these means we were able to isolate dimethyldiiodosilane 2 by co-deposition of thermally generated silicon atoms with pure methyl iodide onto the liquid nitrogen cooled walls of the reactor, followed by warm-up to room temperature. Dimethyldiiodosilane 2, which was formed close to 80% yield, was accompanied by methyltriiodosilane 3 and dimethyltetraiododisilane 4.

References [1] D. Seyferth, Organometallics 2001, 20, 4978-4992. [2] E. G. Rochow, J. Am. Chem. Soc. 1945, 67, 963-965. [3] Müller, R. Chem. Tech. 1950, 2, 41. [4] G. Maier, J. Glatthaar, H. P. Reisenauer, J. Organomet. Chem. 2003, 686, 341-362. [5] G. Maier, J. Glatthaar, Organometallics 2007, 26, 425-428.

77. ...

4

++

2 3

+K

Si H3C I (H3C)I2Si-SiI2(CH3)(H3C)2SiI2 H3CSiI3

1

H3C

Si

I

..I

CH32

H3C

Si

I

CH3

I

C - 9

SLURRY-PHASE DIRECT SYNTHESIS OF TRIETHOXYSILANE WITH CYANIDE AND NITRILE PROMOTERS Kenrick M. Lewisa, Abellard Mereigha, Chi-Lin O’Younga,1, Rudolph A. Cameronb,2 and James S. Ritscherb,3 a Momentive Performance Materials, (formerly GE Advanced Materials, Silicones) 771 Old Sawmill River Rd., Tarrytown, NY 10591, USA bMomentive Performance Materials, (formerly GE Advanced Materials, Silicones) Sistersville Plant, 3500 South State Route 2, Friendly, WV 26146-9750, USA

Copper sources, which have been disclosed for the slurry-phase Direct Synthesis of trialkoxysilanes, include wet and dry process copper (I) chloride, copper (II) organophosphate salts, copper (II) neononanoate, copper (II) hydroxide, nanosized copper (I) chloride, nanosized copper oxides and nanosized copper. When Cu(OH)2 is the source of copper, slurry-phase Direct Synthesis of triethoxysilane (TES) from copper-activated silicon and ethanol does not proceed as straightforwardly as in the cognate methanol reaction. Reactivity and selectivity are improved with the use of nanosized copper sources, but reaction stability is poor. This is caused by the inhibitory effects of acetaldehyde produced via the copper-catalyzed dehydrogenation of ethanol. Organic and inorganic cyanides are additives, which obviate or minimize this side reaction and afford controllably reactive, selective and stable Direct Synthesis of triethoxysilane. Optimal use of these promoters affords silicon conversions > 85 percent, TES 94 – 99 wt% and TEOS 0.5 – 5 wt%. This paper will present data on the performance of CuCN and 1,6-dicyanohexane as promoters as well as comparative data on the catalytic performance of selected copper sources in the Direct Synthesis of TES.

1. Current Address: 5 Old Mill Dr., Poughkeepsie, NY 12603 2. Current Address: Gelest Inc., 612 William Leigh Dr., Tullytown, PA 19007 3. Deceased

C - 10

STEREOCHEMISTRY OF THE HALOGENATION OF Si-Si BOND Masafumi Unno, Hiroyuki Masuda, and Hideyuki Matsumoto Department of Chemistry and Chemical Biology, Graduate School of Engineering, Gunma University, Kiryu 376-8515, JAPAN

Stereochemistry of halogenation has been one of the important topics in organic chemistry. In the halogenation of olefins, formation of halonium ion intermediate was proposed and confirmed. It is well known that Si-Si single bond shows properties like C-C double bond by σ-conjugation. If this can be applied to halogenation of oligosilanes, stereoselective products are obtained.

Fifty years ago, Kumada and co-workers suggested the existence of halonium ion intermediates for the reaction of disilanes with halogens.1 Several ring-opening halogenations of cyclopolysilanes have appeared after that, however, no report has dealt stereochemistry of the reaction so far as we know. In this paper, the following new information is presented: (1) synthesis and X-ray structures of new asymmetrically-substituted cyclotrisilanes; (2) stereochemistry of ring-opening reaction with chlorine and bromine. The structures of the dibromo- and dichlorotrisilanes were determined by X-ray crystallography and spectroscopic methods.2

Our results clearly indicate the existence of bromonium-ion like intermediate in the case of bromination. Single enantiomer pair of dibromotrisilanes was obtained showing the stereoselectivity of the reaction.

SiSi Si

Thex

Ph

Thex

Ph

Thex

Ph

SiSi Si

Thex

Ph

Thex

Ph

Thex

PhBr

SiSi Si

Thex

Br

Thex

Ph

Thex

Ph

Ph Br

+a

a

b

(1R, 3R)

(1S, 3S)

bSi

Si SiThex

Ph

Thex

Ph

Thex

Br

Br Ph

Br2

BrŠ BrŠ

Thex = 1,1,2-trimethylpropyl

_________________________________

1 A. Takeda, M. Kumada, and K. Tarao, Nippon Kagaku Zassi, 78, 999 (1957).

2 M. Unno, H. Masuda, and H. Matsumoto, Bull. Chem. Soc. Jpn, 70, 2449 (1997).

C - 11

SiPh

Me N

[Li]Ln

*

L = ligand

NN

Li

SiR R

R

** *

* * *

SiR'

R'

LiR

N

OMe

*

*

Si-chirality (left), ligand-chirality (middle) and C-chirality ( i h )

STEREOCHEMISTRY OF LITHIATED SILANES Carsten Strohmann, Christian Däschlein, Viktoria H. Gessner

Institut für Anorganische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg; E-mail: mail@carsten-strohmann.de; www.organosilane.de

As part of our studies on metalated stereogenic carbon and silicon centres 1-12 we are interested in synthetic pathways to these metalated systems and in selective transformations of these versatile reagents in organic and organometallic chemistry.

Structural aspects of lithiated silanes will be discussed together with phenomena observed in subsequent reactions and in combination with quantum chemical studies. If e.g. the highly enantiomerically enriched lithiosilane 11 is reacted with benzylhalides, an enantiodivergent transformation – controlled by the applied benzyl halide – occurs, resulting in the inversion (benzyl bromide) or the retention of configuration (benzyl chloride) at the stereogenic silicon centre.5

1. Strohmann, C.; Hörnig, J.; Auer, D. J. Chem. Soc., Chem. Commun. 2002, 766. 2. Strohmann, C.; Seibel, T.; Strohfeldt, K. Angew. Chem. 2003, 115, 4669. 3. Strohmann, C.; Strohfeldt, K.; D. Schildbach, J. Am. Chem. Soc. 2003, 125, 13672. 4. Strohmann, C.; Seibel, T.; Schildbach, D. J. Am. Chem. Soc. 2004, 126, 9876. 5. Strohmann, C.; Bindl, M.; Fraaß, V.C.; Hörnig, J. Angew. Chem. 2004, 116, 1029. 6. Strohmann, C.; Abele, B.C.; Lehmen, K.; Schildbach, D. Angew. Chem. 2005, 117, 3196. 7. Strohmann, C.; Schildbach, D.; Auer, D. J. Am. Chem. Soc. 2005, 127, 7968. 8. Strohmann, C.; Dilsky, S; Strohfeldt, K. Organometallics 2006, 25, 41. 9. Strohmann, C.; Däschlein, C.; Auer, D. J. Am. Chem. Soc. 2006, 128, 704. 10. Strohmann, C.; Lehmen, K.; Dilsky, S. J. Am. Chem. Soc. 2006, 128, 8102. 11. Strohmann, C.; Däschlein, C.; Kellert, M.; Auer, D. Angew. Chem. 2007, in press. 12. Strohmann, C.; Gessner, V.H. Angew. Chem. 2007, in press.

1e.r. > 99:1 94 %, e.r. = 94:6 92 %, e.r. = 5:95

–78 °C– LiCl

–78 °C– LiBr

BnClBnBr

(S)-2(R)-2

SiPhMe

NSi

MePh

N

LiSi

MePh

N

retentioninversion*

C - 12

SILANEDIOL PROTEASE INHIBITORS. ADVANCES IN PREPARATIVE METHODS Wondwossen D. Arasho, Jin Kyung Kim, Yingmei Qi, Sushmita Sen, Swapnil Singh, and Scott McN. Sieburth

Department of Chemistry, Temple University, 1901 N. 13th Street, Philadelphia, PA 19122

The two chiral, functionalized substituents of silanediol-based protease inhibitors, α-substituted-α-amino silanes and α-substituted-β-silyl amides, are critical enzyme recognition elements. Efficient and general methods for assembly of these substituents have been devised. Alpha-amino alkyl silanes can be prepared with metalated N-methyl imines or with Vedejs' asymmetric aziridine metalation. Beta-silyl amides can be constructed by asymmetric hydrosilylation of allyl alcohols or by asymmetric hydroboration/fragmentation of dihydrosiloles.

The application of these chemistries to enzyme inhibitor synthesis, including

matrix metalloprotease (MMP) inhibitors, will be described.

SiHO OHH

N

BO

A

O

HN

β-silyl amide

α-amino silane

SiR R

A

OSi

H

RRA

N LiPh

Ph

NH3B

R'Li

C - 13

A COMPARISON OF THE REACTIVITY OF BROOK AND COURET SILENES TOWARD ALKYNES Kim M. Baines, Kaarina K. Milnes, and Laura C. Pavelka Department of Chemistry, University of Western Ontario, London, Ontario, Canada, N6A 5B7. E-mail: kbaines2@uwo.ca

The addition of alkynes to silenes, compounds containing a silicon-carbon double bond, typically results in the formation of silacyclobutenes. Many examples of this reaction are known; however, very few studies aimed at understanding the mechanism of such cycloaddition reactions have been performed. Knowledge of the reactivity of these compounds will be critical for the future development and applications of this chemistry.

We have recently reported on the addition of the mechanistic probe, trans,trans-2-methoxy-1-methyl-3-phenylcyclopropyl)ethyne, to Brook silenes (non-polar silenes).1 Our results provide unambiguous evidence for the formation of a biradical intermediate during the course of the addition. In this presentation, we will compare the reactivity of the naturally polarized Couret silene toward both simple and cyclopropyl alkynes to the reactivity of Brook silenes. A comparison of the reactivity of Couret silenes and germenes towards alkynes will also be made.

(Me3Si)2SiOSiMe3

t-Bu+

Ph OMe

R(Me3Si)2Si

OSiMe3

t-Bu

H

R OMe

Ph

(Me3Si)2Si

OSiMe3

t-Bu

H

RPh

OMe

Products Products

R = H, Me

_________________________________

1 Milnes, K. K.; Jennings, M. C.; Baines, K. M. J. Am. Chem. Soc. 2006 128, 2491.

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MECHANOCHEMICAL SYNTHESIS OF ALKYL-PASSIVATED SILICON NANOPARTICLES Andrew Heintz, Brian Mitchell, Mark J. Fink

School of Chemical Sciences and Engineering Tulane University, New Orleans, LA 70118

Silicon nanoparticles have unique physical properties due to quantum size

confinement effects and a large surface-to-volume ratio. These highly luminescent particles have potential uses in optical and electronic systems as well as their use as fluorescent biomarkers. Passivation of the nanoparticles by organic groups provides a high degree of stability with minimal effects on their electronic properties. Silicon nanoparticles have been previously prepared by etching of porous silicon, laser induced pyrolysis, Wurtz coupling reactions, high pressure reactions, and aggregation of silicon atoms in a vacuum. We describe a convenient one step process for the simultaneous generation and passivation of silicon nanoparticles through a mechanochemical method employing high energy ball milling. Silicon chips are subjected to mechanical attrition in a reactive organic liquid (i.e. 1-octyne). The fracturing of the silicon in the ball mill continuously exposes fresh surface which reacts with the organic substrate and ultimately leads to the formation of blue luminescent nanoparticles that are surface passivated by strong Si-C bonds. These particles have been characterized by both classical chemical (IR, NMR, dynamic light scattering) and materials (TEM and XRD) techniques. The properties of the silicon nanoparticles produced by this method as well as parallels of the mechanochemical process to the chemistry of reconstructed silicon surfaces will be discussed.

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WATER ON THE SILICON (001) SURFACE: C-DEFECTS AND ELEMENTARY STEPS OF SURFACE OXIDE FORMATION Oliver Warschkow1, Steven R. Schofield2, Nigel A. Marks1, Phillip V. Smith2, Marian R. Radny2, and David R. McKenzie1

1Centre for Quantum Computer Technology, School of Physics, The University of Sydney, Australia 2School of Mathematical and Physical Sciences, The University of Newcastle, Callaghan, Australia

Continuing device miniaturization and the advent of atomic-scale fabrication technologies increasingly requires a full molecular-scale understanding of semiconductor growth and modification processes. The reaction of water with the silicon (001) surface is of particular interest in the growth of ultra-thin film silicon oxide layers. The system has been extensively studied in the literature, with particular focus directed at intra-Si—Si-dimer reaction pathways of H2O dissociation. However, it is becoming clear that inter-dimer reactions (i.e. reactions involving more than one Si—Si dimer) are more important than previously thought. State-of-the-art density functional theory and scanning tunneling microscopy experiments are used in combination to illuminate the complex dissociation pathways of H2O on the silicon (001) surface. Our results provide for the first time a direct mechanistic link between the common C-defect of the silicon surface and the initial stages of surface oxide formation.

C - 16

SOLUTION SYNTHESIS OF SILICON NANOWIRES Hsing-Yu Tuan, Doh C. Lee, Brian A. Korgel

Department of Chemical Engineering, Texas Materials Institute, Center for Nano- and Molecular Science and Technology, The University of Texas at Austin, Austin, TX 78712; korgel@mail.che.utexas.edu

We have developed the synthesis of crystalline high aspect ratio Si nanowires in solution using organosilane reactants like phenylsilane with gold nanocrystals as crystallization seeds. Nanowire growth proceeds by a mechanism analogous to the “vapor-liquid-solid” (VLS) growth mechanism in the gas phase. Solution temperatures of organic solvents like toluene can be reached that exceed the Si:Au or eutectic temperature of ~360oC by pressurizing the solvent above its critical pressure to 50~300 atm. Using this “supercritical” approach, we can synthesize large quantities of Si nanowires in a single reaction. We have also found that alternative metal nanocrystals, like Co, Ni and Cu work well to seed Si nanowire synthesis. Most of these metals seed Si nanowire growth by a solid-phase seeding mechanism, in contrast to Au, which seeds nanowire growth through the formation of a liquid Au:Si solution. In this talk, we will discuss the the organosilane reaction chemistry relevant to nanowire growth, as well as the influence of the seed metal, and the solvent.

Figure. Approximately 50 mg of Si nanowires collected from a single reaction. SEM, TEM and XRD data confirming that the product is crystalline Si nanowires are shown in the insets.

<111>

C - 17

ENZYME-MEDIATED SILICONE CHEMISTRY Karen R. Arnelien, Heidi Stanisic, Travis Dudding, Paul M. Zelisko* Department of Chemistry, Brock University, 500 Glenridge Ave., St. Catharines, Ontario, Canada L2S 3A1

Dibutyltin dilaurate is typically employed as a catalyst to bring about the hydrolysis, and subsequent condensation, of silicones to form cross-linked networks in the room temperature vulcanization (RTV) process. However, given the interest in using silicones as biomaterials, sealants, and lubricants, potentially toxic tin-based catalysts can limit the use of silicones in these applications. This study describes the use of enzymes as catalysts for the cross-linking of silicones in place of the more toxic catalyst systems such as those based on tin. The results indicate that enzymes effectively catalyzes the cross-linking of α,ω-(triethoxysilyl)ethyl-polydimethylsiloxane (TES-PDMS), similar to dibutyltin dilaurate; 29Si-NMR experiments revealed little difference between the products of the dibutyltin dilaurate- and enzyme-catalyzed systems. Computational methods are being employed, in addition to the experimental endeavours, to determine the mechanism occurring within the enzymes’ active site during the RTV process. The computational studies have demonstrated that the enzyme-catalyzed cross-linking mechanism displays components of both natural protease chemistry as well as solution-phase silicon chemistry. The use of these techniques in the development of enzyme-based methodologies for performing “green” silicone reactions will be discussed.

SiSi

OSi

OSi

SiOO

O

O

O

O

n

OSi

O

O

O

SiSi

OSi

OSi

SiOO

O

OSi

Si

SiO

OSi

Si

n

Si

+

+ EtOH

Enzyme

Cross-linked silicone

TES-PDMS

TEOS

C - 18

Narrowly Dispersed Bi-functional Silicone Fluid Anubhav Saxena,*,† Suresh Rajaraman,‡ Mark Leatherman‡

†GE India Technology Centre, 122, EPIP, Hoodi Village, Whitefield Road, Bangalore 560 066, India

‡Silicone Global Technology Specialty Fluids, 771 Old Saw Mill River Road, Tarrytown, NY 10591, USA

Email: anubhav.saxena@momentive.com ABSTRACT Anionic polymerization, being a living polymerization technique, provides a simple and controlled way to synthesize end-functionalized polymers, which contain a reactive end group at one or both chain ends. The synthesis of monofunctional terminated polysiloxane is well-known by anionic polymerization, however, narrowly dispersed polysiloxane having functional groups at both ends are almost rare.1

SiH O

Si SiO

SiH

tBuBut

xy

1

Narrowly dispersed polydimethylsiloxane having hydride chain end functionality at both the ends, was synthesized via anionic polymerization using difunctional anionic initiator.2 The bianionic initiator was prepared in-situ by reacting 1,3- diisopropenyl benzene (DIB) and tertiary butyl lithium (t-BuLi). The molecular weight as well as the “d” length of the resulting bi-functional monodisperse polysiloxane can be well controlled by the molar ratio of cyclic monomer and capping agents. The characterization of resulting polysiloxane was done with the aid of 1H NMR, 29Si NMR spectroscopy, gas chromatography, and gel permeation chromatography.

Reference 1. G. P. Cai, W. P. Weber, Macromolecules, 33, (2000) 6310. 2. A.Saxena, S. Rajaraman, M. Leatherman, Macromolecules, 40, (2007) 752.

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HIGHLY CONTROLLED ASSEMBLY OF SILICONE MACROSTRUCTURES David B. Thompson and Michael A. Brook

Department of Chemistry, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada, L8S 4M1

Interest in the synthesis of highly ordered macrostructures continues to grow. The ability to ’build’ atomically precise three dimensional constructs is a cornerstone of many proposed technological advancements. The challenge of designing syntheses for such structures often lies in the limited number of applicable reactions available. To be of use, coupling reactions must allow not only high yields, but also very high degrees of specificity. In the case of silicone dendrimers, for example, highly reactive chlorosilane routes lead to such structures, but have significant disadvantages in terms of selectivity and scale up.

We report that well defined silicone macrostructures are readily available

through the B(C6F5)3 catalyzed condensation of hydrosiloxanes with alkoxysilanes, liberating alkanes such as ethane or methane. This reagent displays an exceptional level of specificity based on steric influence at both the SiH and ROSi sites. Furthermore, though effective at activating silyl hydrides, B(C6F5)3 does not facilitate silicone redistribution. With careful reaction design and selection of suitably hindered alkoxysilanes, it is possible to easily react one silyl hydride in the presence of another. The manipulation of these principles allows for the construction of very well ordered siloxane macrostructures using readily available starting materials. The reaction proceeds cleanly and in high yields, with gaseous byproducts obviating the need for laborious purification.

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SYNTHESIS, STRUCTURE, AND PROPERTIES OF SILSESQUIOXANES -NOVEL LADDER AND CUBIC SILSESQUIOXANES- Takahiro Gunji, Hiroyasu Seki, Naoto Ueda, and Yoshimoto Abe Department of Pure and Applied Chemistry, Tokyo University of science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan. Tel: +81-4-7122-9499, Fax: +81-4-7123-9890, E-mail: gunji@rs.noda.tus.ac.jp, abeyoshi@rs.noda.tus.ac.jp Siloxanes, especially ladder and cubic silsesquioxanes, are the attractive targets for not only research work but also application to high-performance materials. One of the problems is the design and the characterization of well-controlled ladder structure as well as the synthesis route to polyhedral silsesquioxanes with sila-functional groups and solubility in organic solvents. In this work, novel ladder silsesquioxanes with three and five-membered rings 1 and also a facile synthesis route of alkoxy derivatives of the polyhedral silsesquioxanes 2 will be reported together with the synthesis of ladder polysilsesquioxanes of which the structure is well-controlled compared with those reported earlier.

X

R

Si O

R

Si O

R

Si

O O O

X

SiX O Si O Si X

R R R OOSi

O

OOSi

Si

OO

SiO

O

O

Si

O

Si

O SiSi

RO OR

RORO

RO OR

ORRO

n

(n=1, 2, 3; R=Me, Ph; X=NCO, OBut) (R=Me, Et, Pri, But, Oct, Cy, TMS)

1 2

C - 21

ACTIVATION OF SILICON-CHLORIDE BONDS WITH RUTHENIUM(0) COMPLEXES AND REACTIVITY OF CHLORO(ORGANOSILYL)RUTHENIUM(II) COMPLEXES WITH ACETYLENE Noah L. Wieder, Noah S. Frank, Hyojong Yoo, Patrick J. Carroll, and Donald H. Berry*

Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104 berry@sas.upenn.edu

A novel class of Ru(0) complexes [η2-[N3]Ru(η6-Toluene), where [N3] = 2,6-(MesitylN=CMe2)2C5H3N, reacts with alkylchlorosilanes, MenSiCl4-n (n=0, 1, 2, or 3), to yield 16 electron chloro(organosilyl)ruthenium complexes, [N3]Ru(Cl)SiMenCl4-n . The oxidative addition of Si-Cl bonds to transition metals may prove useful for further functionalizations, mirroring the well known and widely used oxidative addition of carbon-halogen bonds. The chloro(organosilyl)ruthenium complex [N3]Ru(Cl)SiMe2Cl 1 reacts with acetylene and undergoes undergoes acetylene insertion into the ruthenium silicon bond. Under excess acetylene, two isomers of the resultant 18 electron ruthenium vinyl silane product, [N3]Ru(Cl)(CHCHSiMe2Cl)(η2-HC≡CH) 2a, 2b, are observed initially. After ca. 12h, only the thermodynamically preferred isomer, 2b, is present whereas the kinetic isomer, 2a, is not observed. Upon removal of acetylene, the 16 electron complex [N3]Ru(Cl)(CHCHSiMe2Cl) 3 is formed, which has been structurally characterized. The crystal structure of 3 reveals that it is the trans insertion product. 3 readily coordinates acetylene, regenerating 2b only. Structural studies and mechanistic implications for metal-catalyzed hydrosilylation will be presented.

C - 22

SYNTHESIS AND REACTIVITY OF CATIONIC IRIDIUM SILYLENE COMPLEXES SUPPORTED BY A PNP PINCER LIGAND Elisa Calimano, T. Don Tilley

Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720

A new family of cationic iridium silylene complexes supported by a rigid PNP pincer ligand (PNP = [N(2-PiPr2-4-Me-C6H3)2]

-) has been synthesized via hydride abstraction from the corresponding iridium silyl hydride. Characterization of these complexes includes characteristic downfield-shifted 29Si NMR resonances from 220 ppm to 310 ppm. Recently, a cationic ruthenium silylene complex has been reported to catalyze the hydrosilation of alkenes via direct insertion of an alkene into the Si-H bond. Similarly, these cationic iridium silylene complexes react with alkenes and are competent catalysts for hydrosilation. The stoichiometric and catalytic reactivity of these complexes will be discussed.

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ELECTRONIC INTERACTIONS IN TRANSITION METAL CONTAINING POLYSILANES Harald Stuegera, Markus Braunwartha, Jean-Rene Hamonb, Claude Lapinteb

aInstitute of Inorganic Chemistry, Graz University of Technology, Graz, Austria bUMR 6226, CNRS-Université de Rennes 1, Rennes Cedex, France

Although it is well established, that the σ-electrons in polysilanes are delocalized rather effectively along the silicon backbone resulting in unique electronic properties, silicon was found to be only a weak charge transmitter, when donor and acceptor moieties are connected by permethylated Si-Si-chains. Thus, ferrocenylpolysilanes of the general structure Fc-(Si)n-A (1), where ferrocene as a donor is linked to the (2,2-dicyanoethenyl)phenyl acceptor group, exhibit only negligible intramolecular ground state donor acceptor interactions [1,2]. When transition metals are directly attached to the polysilane chain, however, strongly coupled systems are obtained. We synthesized the donor/acceptor substituted disilanes 2 and found strong electronic coupling within the [M]-Si-Si-Caryl fragment using UV/Vis absorption spectroscopy and cyclic voltammetry. The crystal structures of 2, furthermore, show an all-trans-array of the central [M]-Si-Si-Caryl moiety, what is a basic requirement for optimum through-bond interaction.

Furthermore, binuclear complexes 3 with the transition metal substituents linked

to the polysilane chain by acetylene bridges, were prepared from [C5Me5dppeFe]OTf (dppe = 1,2- bis(diphenylphosphino)ethane; OTf = F3CSO3-) and HC≡C-(SiMe2)n-C≡CH. Significant substituent–substituent interactions via the Si-Si bonds were observed in the oxidized compounds 3+ by spectroelectrochemistry. Structural, UV/vis absorption and electrochemical data of 3 and 3+ will be presented and discussed in detail.

_________________________________ [1] H.K.Sharma, K.H.Pannell, I.Ledoux, J.Zyss, A.Ceccanti, P.Zanello, Organometallics 19 (2000) 770 [2] Ch.Grogger, H.Siegl, H.Rautz, H.Stüger, in: N.Auner, J.Weis (eds.), Organosilicon Chemistry IV Verlag Chemie, Weinheim (2000), p. 384

M SiMe

MeSiMe

MeOC

OCCH=C(CN)2

(Si)nFe

CH=C(CN)2

(Si)n = -Si2Me4-; -Si6Me12-

1 2 M = Fe, Ru

FePh2P PPh2

(SiMe2)nCC C C FePPh2Ph2P

Me

MeMe

MeMe Me

Me

MeMe

Me

3

n = 2, 3, 4

C - 24

DENDRITIC CALIXARENE HOSTS FOR EFFICIENT BINDING OF METAL IONS Joseph B. Lambert, Seung-Hyun Kang, Chunqing Liu, and Kuangbiao Ma

Department of Chemistry, Northwestern University, Evanston, Illinois 60208 USA A new class of polycalyx[4]arene hosts has been constructed based on a carbosilane dendrimer architecture. Each dendritic branch terminates with a calyx[4]arene entity. To date we have synthesized the zeroth generation (G0) example with four calyx[4]arenes and the first generation (G1) example with 12 calyx[4]arenes. Solvent extraction of Cu(II) by these branched or dendritic polycalyx[4]arenes from water to organic media was compared with extraction of a model containing only a single calyx[4]arene. All materials showed the highest extractability toward Cu(II) at pH 11. Coordination was enhanced as the number of calyx[4]arene units per molecule increased. Calibrated plots indicated that all four calyx[4]arene units in the G0 molecule and all 12 in the G1 molecule were complexed with Cu(II).

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SYNTHESIS AND STUDIES OF POLYCARBOSILANE-PMMA GRAFT COPOLYMERS AS POTENTIAL LOW-k DIELECTRIC MATERIALS Jay-Yong Hyun*, Leonard V. Interrante*, Chang Y. Ryu*, Pei-I Wang#, and Toh-Ming Lu#

Departments of Chemistry* and Physics#, Rensselaer Polytechnic Institute, Troy, NY 12180-3590

Based on our original synthesis of a cyclolinear polycarbosilane (CLPCS)1 and the identification of its favorable dielectric and thermomechanical properties for potential application as a low-k interlayer dielectric and Cu barrier/capping layer in future generations of integrated circuits2, we have been pursuing the synthesis of graft copolymers of this CLPCS backbone structure with polymethylmethacrylate (PMMA), in which the PMMA grafts can serve as sacrificial pore generators for generation of porous low-k films. The starting polymer in this case is a tolyl-substituted disilacyclobutane-hexylene polymer of the type, [-{SiTolyl(CH2)2SiTolyl}-(CH2)6-]n, which is obtained by acyclic diene metathesis (ADMET) polymerization of the appropriate diene-substituted 1,3-disilacyclobutane monomer, followed by reduction of the intermediate polyolefin.

Bromination of the tolyl Me groups, and anionic coupling with PMMA- anions of varying sizes (2.5, 5 and 10K) yields a series of random graft copolymers of the type CLPCS-g-PMMA in which the weight percentage of PMMA is 25-33%3. DSC, AFM and SAXS studies of the resultant polycarbosilane films spin-coated onto Si wafer pieces show microphase separation for the two copolymers which contain longer PMMA grafts (5 and 10K), whereas with the 2.5K PMMA graft, no microphase separation is evident.

TGA and DSC studies of these copolymers suggest that crosslinking of the CLPCS base polymer occurs before fragmentation of the PMMA as the temperature of the films are increased to ca. 400oC, yielding a film with some porosity and a marginally lower dielectric constant (down to k=2.3, from 2.4 for the PCS) after this thermal treatment. Current efforts are focusing on the effective removal of the PMMA fragments by extraction with solvent and on the use of UV irradiation to cure the films at a lower temperature (than the ca. 300oC currently required by thermal treatment alone) and fragment the PMMA prior to thermal treatment to complete the crosslinking of the PCS and eliminate the PMMA. ______________________________________ 1 Zhizhong Wu, Jerry P. Papandrea, Tom Apple and Leonard V. Interrante, "Cross-linkable Carbosilane Polymers with Imbedded Disilacyclobutane Rings, Derived from Acyclic Diene Metathesis (ADMET) Polymerization”, Macromolecules, 37(14), 5257-5264 (2004). 2 P.-I. Wang, Z. Wu, T.-M. Lu and L.V. Interrante, “A Novel Polycarbosilane-based Low-k Material”, J. Electrochem. Soc., 153(4), G267-G271 (2006). 3 Jaeyong Hyun, Junwon, Han, Chang Y Ryu and Leonard V. Interrante, “Synthesis of Cyclolinear Poly(carbosilane)-g-poly(methyl methacrylate or styrene) Random Copolymers. Macromolecules 39(25), 8684-8691 (2006).

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PENTACOORDINATION OF SILICON BY FIVE DIFFERENT

LIGAND ATOMS: NEUTRAL SILICON(IV) COMPLEXES WITH

AN SiXSONC (X = Cl, Br, I) SKELETON Reinhold Tacke, Stefan Metz, Christian Burschka, Daniela Platte

Universität Würzburg, Institut für Anorganische Chemie, Am Hubland, D-97074 Würzburg, Germany

In continuation of our studies on neutral penta- and hexacoordinate silicon(IV) complexes with dianionic tridentate ligands,1 compound 1 was synthesized starting from PhSiCl3 (Scheme 1). This compound with an SiClSONC skeleton contains five different ligand atoms. Treatment of 1 with Me3SiBr and Me3SiI leads to compounds 2 and 3, respectively, which also represent five different ligand atoms and which also contain novel SiXSONC (X = Br, I) skeletons. The silicon(IV) complex 3 is the first higher-coordinate silicon(IV) complex with an Si–I bond. Compounds 1–3 were structurally characterized by solid-state and solution NMR spectroscopy and single-crystal X-ray diffraction. Compound 1 has been used as a precursor for the synthesis of many other higher-coordinate silicon(IV) complexes (substitution of the chloro ligand) with quite new Si-coordination polyhedra (e.g. SiSO2NC, SiSON2C), making this compound a unique starting material in the chemistry of higher-coordinate silicon.

Scheme 1

_________________________________

1 O. Seiler, C. Burschka, S. Metz, M. Penka, R. Tacke, Chem. Eur. J. 2005, 11, 7379–7386.

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Synthesis and Characterization of Imidazole-Silane Complexes Tatiana V. Eliseeva, Wendy L. Lewis, Matthew J. Panzner, Paul D. Custer, Venkat R. Dudipala, Matthew P. Espe, Wiley Youngs, Claire A. Tessier*

University of Akron, Department of Chemistry, Akron, OH, USA, 44325-3601

One step of the biomineralization of silicon in sponges appears to involve the interaction ortho-silicic acid with a histidine–serine site in a silicatein (protein) via a five-coordinated silicon intermediate. In order to model this chemistry, two projects have been developed.

N

N NN

(CH2)mNN

Because an imidazole ring is the reactive functional group of a histine in a protein, the reaction of imidazoles 1 and 2 with various alkoxy and chloro silanes have been investigated. Some evidence for five- or six-coordination has been obtained from 1 2 29Si spectra.

NHNHO

HO(CH2)10

N

N

In the second, more ambitious project, the reactions of 3 and 4 with alkoxy and chloro silanes have been studied. Compounds 3 and 4 model some of the features of both the serine and hisidine amino acid residues of the silicatein, simultaneously. The reactions of 3 and 4 with chloro and alkoxy silanes give

3 4

products in which the silicon is four-coordinate. The crystal structure of the product of 3 and SiPh3Cl is shown below. The Si reagent reacted selectively with the –OH group rather than the N-H group.

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NOVEL NEUTRAL HEXACOORDINATE SILICON (IV) COMPLEXES WITH -O, N, N- TRIDENTATE AND -O, N, N, O-

TETRADENTATE SCHIFF BASE LIGANDS Gerardo González-García and J. Alfredo Gutiérrez

Universidad de Guanajuato, Facultad de Química. Noria Alta s/n. Guanajuato, Gto. 36050 México. The study of higher-coordinated silicon complexes with salen type ligands has been leading to new insights into the field of silicon coordination chemistry, e.g. Si-C bond activation by UV light1 or the disproportion of Si-Si bond as a consequence of an increase in the coordination number of silicon.2 Tacke et al.3 have been using Si(NCS)4 and Si(NCO)4 as starting materials for the preparation of neutral higher-coordinate silicon (IV) complexes with SiO2N3 and SiO4N2 coordinating frameworks.

Herein we report the synthesis and characterization of new neutral hexacoordinate silicon (IV) complexes with SiCO2N3 and SiON5 coordinating frameworks containing thiocyanate -N ligand. The reactions of the tridentate -N,N,O- and tetradentate -O,N,N,O- Schiff base ligands with HSi(NCS)3 and HMeSi(NCS)2

respectively lead to the formation of the new hexacoordinate silicon complexes shown in the scheme.

1. Wagler, J.; Bohme, U.; Roewer, G. Angew. Chem. Int. Ed. 2002, 41, 1732. 2. Wagler, J.; Bohme, U.; Roewer, G. Organometallics 2004, 23, 6066; Wagler, J.

Organometallics 2007, 26, 155. 3. Seiler O., Burschka C., Fischer M., Penka M. and Tacke R. Inorg. Chem. 2005.

44, 2337; Seiler O., Burschka C., Penka M. and Tacke R. Chem. Eur. J. 2005. 11, 7379.

Acknowledgment: This work was supported by CONACyT and Universidad de Guanajuato.

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SYNTHESIS OF POLY(DIMETHYLSILOXANE) WELL ARCHITECTURED BLOCK COPOLYMERS IN MINIEMULSION USING IODINE TRANSFER POLYMERIZATION Emmanuel Pouget, Jeff Tonnar, Patrick Lacroix-Desmazes, Bernard Boutevin Institut Charles Gerhardt – UMR 5253 CNRS/UM2/ENSCM/UM1 - Ingénierie et Architectures Macromoléculaires, Ecole Nationale Supérieure de Chimie de Montpellier, 8 rue de l’Ecole Normale, 34296 Montpellier Cedex 5, France. emmanuel.pouget@enscm.fr; jeff.tonnar@enscm.fr; patrick.lacroix-desmazes@enscm.fr; bernard.boutevin@enscm.fr

The first synthesis of poly(styrene)-b-poly(dimethylsiloxane)-b-poly(styrene) triblock copolymer in miniemulsion has been achieved by controlled/living radical polymerization of styrene using a modified hydroxypropyl terminated poly(dimethylsiloxane) as a transfer agent for Iodine Transfer Polymerization (ITP).1 First an , -hydroxypropyl poly(dimethylsiloxane) was modified by esterification with 2-bromopropionic acid. The second step consisted in a nucleophilic substitution of bromine by iodine through the reaction with sodium iodide in acetone. Then, miniemulsion polymerization of styrene was performed in the presence of sodium dodecylsulfate (SDS) as surfactant and , -diiodo-poly(dimethylsiloxane) as both the hydrophobe and the macrotransfer agent and 2,2’-azobisisobutyronitrile as radical initiator. A good correlation between theoretical and experimental molecular weights was obtained. A kinetic study showed an increase of the molecular weight with conversion, and a chain extension led to a shift of the molecular weight distribution, giving evidence for the living character of the triblock copolymers. The miniemulsion process and the high polymerization yield reduce the volatile organic compounds emission compared with the classical mass or solution processes and leads to ready-to-use stable white latexes. The triblock copolymers have been studied by microscopy.

(1) Pouget, E.; Tonnar, J.; Eloy, C.; Lacroix-Desmazes, P.; Boutevin, B.

Macromolecules 2006, 39, 6009-6016.

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SYNTHESIS AND CATALYTIC ACTIVITY OF TITANIUM FUNCTIONALIZED SILICONE NANOSPHERES. Christopher A. Bradley, Meredith J. McMurdo, T. Don Tilley Department of Chemistry, University of California, Berkeley, 326 Lewis Hall, Berkeley, CA, 94720-1460. Preparation of silicone substituted nanospheres in the 10-20 nm size regime was accomplished by emulsion polymerization of the corresponding trimethoxysilane monomers, RSi(OMe)3. The spheres, characterized by numerous techniques (TEM, dynamic light scattering, and porosimetry) were found to be high surface area, hydrophobic materials containing surface silanol functionality. In particular, the nanosphere where R = Me was used for grafting of Ti(OiPr)4 to give site- isolated, four coordinate surface titanium centers. This material proved competent for the selective catalytic oxidation of cyclohexene using organic oxidants. The grafting chemistry of other metals on the nanosphere surfaces, along with the characterization and catalytic activity of these materials will also be presented.

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POLYSILOXANE NANOFIBERS VIA SURFACE INDUCED POLYMERIZATION OF ORGANOTRICHLOROSILANES De-ann E. Rollings, Jonathan G.C. Veinot Department of Chemistry, University of Alberta, Edmonton, Alberta,Canada T6G 2G2 Standard methods for fabricating one-dimensional materials include electro-spinning, vapour liquid solid deposition and template-directed synthesis. We have discovered and fine-tuned a new method for the fabrication of nanofibers based on surface induced polymerization of organotrichlorosilanes. This method yields polysiloxane fibers of with varying morphologies previously not accessible with the techniques listed above, including tailored length and sub-100 nm diameter. The fibers can be prepared on a variety of hydroxylated surfaces, withstand temperatures of > 1000°C and exhibit superhydrophobicity after functionalization with a fluorinating agent. Topics of discussion will include the mechanism of formation, critical parameters affecting the aspect ratio and surface property alteration via functionalization.

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POSTER

ABSTRACTS

THE DIRECT REACTION OF METHYL BROMIDE WITH SILICON

Bernard Kanner1, Hyman Stollar2, Boris Kaufman2, Evgeny Tartakovsky2 and Michael Kopolov2 1 5 Robin Lane, West Nyack, NY 10994, 2 Bromine Compounds Ltd., Beersheva, Israel The reaction of methyl bromide with silicon has been largely ignored over the last 60 years. In the few reported investigations, 1-5 the selectivity to dimethyldibromosilane has been low, ranging from 24 to 71%. Conditions that give good selectivity to dimethyldichlorosilane were not optimal for obtaining good selectivity to dimethyldibromosilane.5 No one has reported results that come close to the 90% selectivity to dimethyldichlorosilane obtained in the Rochow-Müller Process.

We now wish to report, from studies carried out at Bromine Compounds Ltd., 93 mol % selectivity to dimethyldibromosilane has been obtained over a complete silicon bed turnover. Silicon of 98.5% purity was used. To this was added 2% of powdered Cu metal, 0.1% ZnO and 0.1% Sn. The mass was activated by preheating to 350°C. Reaction with methyl bromide was then carried out at 325°C in a fluidized bed reactor. Silicon conversion to silane products averaged 5%/hr. These results demonstrate that comparable selectivities are now achievable whether methyl chloride or methyl bromide is reacted with silicon. A feature in favor of the methylbromosilane route is the substantially larger difference in boiling points of the di- and trifunctional derivatives as compared to the corresponding chlorosilanes. This allows the separation of bromosilanes by simple distillation equipment compared to the much more expensive 100 + theoretical plate columns now required to separate the corresponding chlorosilanes. References

1. K. Moedritzer and J. R. van Wazer, Inorg. Chem., 5 (1966) 547-552 2. Ch. Horny and M. Guinet, Fr. Patent 1,046,295 (1953) 3. A. V. Topichev and N. S. Nametkin, CA 59 (1963) 6428h 4. F. Jost, D. Tomanova, J. Joklik, Z. Pelzabauer and V. Bazant, Coll. Czech.

Chem. Comm. 32 (1967) 2310-2319 5. K. M. Lewis and B. Kanner, US Pat. 4,593,114 (1986)

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STRUCTURE AND PROPERTIES OF 1,1-DIMETHYL-2,3,4,5-TETRAKIS(4-TRIMETHYLSILYLPHENYL)SILOLE Amy E. Brown, Barrett E. Eichler

Chemistry and Physics Department, Northwest Missouri State University, 800 University Drive, Maryville, MO, USA 64468

Researchers have shown that siloles are efficient electroluminescent materials that have been incorporated into organic light-emitting diodes (OLEDs) as the emitting layer.1 Kumada and co-workers2 introduced a reaction that selectively forms siloles from diarylacetylenes and 1,1,2,2-tetramethyldisilane via catalysis with NiCl2(PEt3)2. More recently, Sanji and co-workers,3 used diarylacetylenes to synthesize silole-core dendrimers that showed intense fluorescence in solution, as well as strong energy transfer from the dendron units to the silole.

Using bis(4-trimethylsilylphenyl)ethyne under similar conditions, we have synthesized a novel silole, 1,1-dimethyl-2,3,4,5-tetrakis(4-trimethylsilylphenyl)silole. We will report the X-ray structure and other characterization of the title compound. Solution photoluminescence of this novel compound will be discussed, which is of interest as there are electropositive trimethylsilyl groups on the para positions of the phenyl rings.

Me3Si SiMe32Ni catalyst

HSiMe2SiMe2H

SiMe2Me3Si

Me3Si SiMe3

SiMe3

_________________________________

(1) Recent examples of silole-based OLEDs: a) Lee, J.; Liu, Q.-D.; Bai, D.-R.; Kang, Y.; Tao, Y.; Wang, S. Organometallics 2004, 23, 6205-6213. b) Kim, W.; Palilis, L. C.; Uchida, M.; Kafafi, Z. H. Chem. Mater. 2004, 16, 4681-4686. c) Son, H.-J.; Han, W.-S.; Chun, J.-Y.; Lee, C.-J.; Han, J.-I.; Ko, J.; Ook Kang, S. Organometallics 2007, 26, 519-526.

(2) Okinoshima, H.; Yamamoto, K.; Kumada, M. J. Am. Chem. Soc. 1972, 94, 9263-9264.

(3) a) Sanji, T.; Ishiwata, H.; Kaizuka, T.; Tanaka, M.; Sakurai, H.; Nagahata, R.; Takeguchi, K. Chem. Lett. 2005, 34, 1130-1131. b) Sanji, T.; Ishiwata, H.; Kaizuka, T.; Tanaka, M.; Sakurai, H.; Nagahata, R.; Takeguchi, K. Can. J. Chem. 2005, 83, 646-651.

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SYNTHESIS OF STRAINED RING COMPOUNDS: PRECURSORS TO SIMPLE DISILYNES VIA MOLECULAR BEAM METHODS Kothanda Rama Pichaandi, Ranganathan Subramanian, Mark Sulkes, Mark Fink Chemistry Department, Tulane University, New Orleans, LA 70118, USA.

Carbon-carbon double and triple bonds are very common in organic chemistry. Multiple bonds between silicon atoms, lying just below carbon in the periodic table, are still unusual.1 Very recently Sekiguchi reported a stable disilyne RSi≡SiR with a bulky substituent2 .Much of our knowledge about simple disilynes like dimethyldisilyne and diphenyldisilyne is based on theoretical calculations. As suggested by Apeloig, the obstacles that prevent the synthesis and observation of simple disilynes are (i) the existence of a more stable isomer (for example in the case dimethyldisilyne, the dimethyldisilavinylidene isomer) (ii) the small energy barriers for isomerization, (iii) their intrinsically high reactivity.3 Therefore the generation of these simple disilynes is a great challenge and of great value for silicon chemistry. In order to detect the formation and reactions of these simple disilynes, upon generation, they should be removed from the reaction site and cooled down to very low temperatures to prevent or slow down the isomerization. Reactive laser ablation coupled with molecular beam techniques is a powerful tool to study this type of highly reactive species.4,5 Potential precursors to the generation of disilynes are highly strained bis(silaranes) (1). Synthesis and characterization of three bis(silaranes) with phenyl, methyl and tert-butyl substituents and their laser ablation results will be discussed. The expected pattern of decomposition is given below.

Si Si

R

R

Si Si RR +

1 R = Ph, Me, tert-butyl

_______________________________ . 1. Weidenbruch, M., Chem. Org. Silicon Comp., 2001. 3: p. 391-428. 2. Sekiguchi, A., Kinjo,Rei, Ichinohe,Masaaki, Science, 2004. 305: p. 1755- 1757. 3. Karni, M., Kapp, J., Schleyer, P. V. R.,Apeloig, Y, Chem. Org. Silicon Comp.,

2001. 1: p. 3. 4. Tan, X.Q., T. G. Wright, and T. A. Miller, in Jet spectroscopy and Molecular

Dynamics, J. Hollas and P. M., D. Blackie., Editors. 2005. 5. Engelking, P.C., Chem. Rev., 1991. 91: p. 399-414.

.

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SOLVENT EFFECTS ON THE PROPERTIES OF GELS OBTAINED FROM FORMULATIONS OF TEOS AND SOME ADDITIVES USED IN STONE CONSOLIDATION 1Carmen Salazar, 1Jorge Cervantes, 2Sergio Calixto, 3Sergio Alonso Romero 1Facultad de Química, Universidad de Guanajuato, Noria Alta S/N C.P. 36050, Guanajuato Gto.México. 2Centro de Investigaciones en Óptica, León, Guanajuato, México. 3 CIATEC. A.C, León, Guanajuato, México. carmen1103@quijote.ugto.mx, jauregi@quijote.ugto.mx

Tetraethoxysilane (TEOS) is the base of some formulation used in the consolidantion of stones. Several projects in our group have been directed to the study of degradation mechanisms of stones from historical buildings and also in the solution of such degradation problems1-3. The ability of TOES to be hydrolyzed and form a gel of SiO2 is the fundament of the consolidation process. The TEOS is applied to stone as a sol solution of low viscosity in situ via sol-gel process. The result is the formation of a gel film inside the degraded stone that improves the mechanical properties. However one problem commonly observed during the consolidation process is the gel cracking during the drying stage. To avoid the gel fractures, we have prepared formulations using TEOS and fillers such as colloidal silica (200nm in diameter.) and PDMS-OH. Protic and aprotic solvents were used, because the stability of the colloidal particles depends on the properties of the solvent. The solvent has influence in the final characteristics and texture of the hybrid material. Nevertheless the incorporation of these additives using both solvents enhances in some way the gel properties (porosity and elasticity) since the point of view of the different “history” of the gel formation. The characterization of the xerogel was carried out using nitrogen adsorption, 29Si Solid state NMR and AFM. Acknowledgments. The authors wish to thank CONACYT-Mexico for financial support. 1. J. Cervantes, G. Mendoza-Díaz, Dolores E. Alvarez-Gasca and Antonio Martínez-Richa. Solid State Nuclear Magnetic Resonance, 13, 263-269(1999). 2. R. Zarraga, D. Alvarez-Gasca and J. Cervantes. Journal of Silicon Chemistry, I, 397-402 (2002). 3. R. Zarraga, G. Wheeler, J. Cervantes. Manuscript in preparation

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THE EFFECT OF CHELATING PHOSPHINE LIGANDS ON SIH BOND ACTIVATION REACTIONS AT PLATINUM Janet Braddock-Wilking, Ngamjit Praingam, Nigam P. Rath

Department of Chemistry and Biochemistry, University of Missouri-St. Louis, St. Louis, MO 63121, USA

Silicon-hydrogen bond activation reactions involving silafluorene (H2SiC12H8, 1) and 3,7-di-tert-butylsilafluorene (H2SiC20H24, 2) with Pt(0) and Pt(II) phosphine complexes produced a variety of different types of Pt-Si complexes depending on the nature of phosphine used. The Pt(II) complex, (Me3P)2PtMe2 containing the small and basic PMe3 ligand reacted with 1 or 2 to produce six-coordinate complexes, [(Me3P)2Pt(H)2(SiAr2H)2, 3-4, respectively]. The reaction of 1 with (dmpe)PtMe2 (dmpe = 1,2-bis(dimethylphosphino)ethane) produced a different six-coordinate complex that contained three silyl ligands, fac-(dmpe)(H)Pt(SiAr2H)3 (5) whose structure was confirmed by X-ray crystallography. When the chelating diphosphine was changed to 1,3-bis(diphenylphosphino)propane (dppp), reaction of (dppp)PtMe2 with 1 produced as the major complex a mononuclear bis(silyl) species, (dppp)Pt(SiAr2H)2 (6). In contrast, the Pt(II) complex, (PN)PtMe2 containing the hemilabile chelate ligand, Ph2PCH2CH2NMe2 (PN) generated two major Pt-Si containing products upon reaction with 1, (PN)Pt(SiAr2H)2 (7) and cis-(Me2NCH2CH2PPh2)2Pt(H)(SiAr2H) (8). The characterization of complexes 3-8 will be described.

P - 5

S1

N1

Si2

Si1

Si3

Si4

O2

O3O4

O1

C10

C5C6

C7

C8

C4

C3

C2

C1

C12

C13C14

C15

C11

C9

SELECTIVE SI–C-BOND CLEAVAGE AS SYNTHETIC ENTRY TO

FUNCTIONALIZED LITHIOSILANES

Christian Däschlein, Dominik Auer, Carsten Strohmann*

Institute of Inorganic Chemitry, University of Wuerzburg, Wuerzburg, Germany

Email: mail@carsten-strohmann.de

Functionalized lithiosilanes are versatile reagents in organic and organometallic chemistry e.g. for the nucleophilic introduction of protecting groups, synthesis of silylsubstituted transition metal complexes or silicon-based polymers.1-4 In common, lithiosilanes are prepared by Si–Si-bond cleavage with lithium metal. Though, the synthetic pathways to functionalized lithiosilanes are extremely limited.

Treatment of the enantiomerically pure phenyl-substituted disilane (R)-1 with lithium metal afforded the highly enantiomerically enriched lithiosilane 2 by selective cleavage of a Si–Ph-bond. After reaction of 2 with pentamethylchlorodisilane, the resulting product (R)-3 crystallizes as the hydrogensulfate (R)-3∙H2SO4, which represents the first example of a highly enantiomerically enriched tetrasilane (see Figure 1 and 2).4

The stereochemical course of the cleavage and substitution reactions based on the determination of the absolute configurations of the involved compounds will be presented. The synthetic potential of this unanticipated and novel Si–C-bond cleavage reaction will be shown on selected examples.3,4

__________ 1. Strohmann, C.; Hörnig, J.; Auer, D.; Chem. Commun. 2002, 766. 2. Strohmann, C.; Schildbach, D.; Auer, D.; J. Am. Chem. Soc. 2005, 127, 7968. 3. Strohmann, C.; Däschlein, C.; Auer, D.; J. Am. Chem. Soc. 2006, 128, 704. 4. Strohmann, C.; Däschlein, C.; Kellert, M.; Auer, D.; Angew. Chem. 2007, in press.

SiMe

Me3Si N

SiMe2SiMe3Si

MeMe3Si N

2 Li SiLiMe3Si

Me N

2

Me3SiSiMe2Cl

(R)-1

(R)-3; e.r. ≥ 98:2

–50 °C

–78 °C– LiCl

*

Li

–

Figure 1 Selective silicon-phenyl bond cleavage with lithium.

Figure 2 Structure of (R)-3∙H2SO4 .

P - 6

Figure 1 Si-chirality (top) and ligand- chirality (bottom).

Figure 2 Crystall structure of (–)-sparteine coordinated lithiosilanes.

STUDIES ON (–)-SPARTEINE COORDINATED LITHIOSILANES

Christian Däschlein, Carsten Strohmann* Institute of Inorganic Chemistry, University of Wuerzburg, Am Hubland, D-97074

Wuerzburg, Germany

As part of our studies on enantiomerically enriched lithiosilanes1-4 we are interested in the molecular structures and reactivities of (–)-sparteine coordinated lithiosilanes. Unlike systems with a stereogenic silicon center, here the chirality is encoded in the ligand (see Figure 1). Compounds with four-coordinated lithium centres like 1 and 2 possess a stereogenic lithium centre and two diastereomers can be formed (see Figure 2). Larger silyl-groups result in three-coordinated lithium centres (see 3, Figure 2). As a result, the chirality at the lithium is lost and only one enantiomer is possible anymore.3 As chirality in these systems is induced at the silicon center by the (–)-sparteine ligand, for the silicon to successfully transfer stereogenic information to electrophiles (i.g., to act as a chiral nucleophile), the Si–Li contact has to remain intact in solution. The crystal structures and these aspects will be discussed in combination with quantum chemical and NMR spectroscopic studies.

___________ 1. Strohmann, C.; Bindl, M.; Vraaß, V. C.; Hörnig, J.; Angew. Chem. Int. ed. 2004, 43,

1011. 2. Strohmann, C.; Schildbach, D.; Auer, D.; J. Am. Chem. Soc. 2005, 127, 7968. 3. Strohmann, C.; Däschlein, C.; Auer, D.; J. Am. Chem. Soc. 2006, 128, 704. 4. Strohmann, C.; Däschlein, C.; Kellert, M.; Auer, D.; Angew. Chem. 2007, in press.

SiPh

Me N

[Li]Ln

*

L = ligand

NN

Li

SiR R

R

** *

* * *

Si

LiO

N1N2

(S)

(S)(S)

(R)

(R)(R)

(s)Li

Si

O

N1N2

(S)

(S)(S)

(R)

(R)(R)

(s)

(S)

(S)(S) (R)

(R)

(R)

Si

N1

N2N3

Li

Me2PhSiLi∙(–)-sparteine∙THF 1

MePh2SiLi∙(–)-sparteine∙THF 2

Ph2(Et2N)SiLi∙(–)- sparteine 3

P - 7

Li

Si

C

Si

LiC

Si

N1

OLi

N2

C3

EXPERIMENTAL CHARGE-DENSITY STUDIES OF α-LITHIATED

BENZYLSILANES

Christian Däschlein, Timo Seibel, Daniel Schildbach, Viktoria H. Gessner, Holger Ott, Ulrike Flierler, Dirk Leusser, Dietmar Stalke, Carsten Strohmann*

Institut of Inorganic Chemistry, University of Wuerzburg, Am Hubland,D-97074 Wuerzburg, Germany

Definitely, lithium organic compounds are the leading reagents in modern synthetic chemistry, although many questions concerning the structure/reactivity patterns of these polar metalorganyl still remain unanswered. Aggregation and deaggregation phenomena are the reactivity and rate-determining key features in lithiumorganics, whereas in most cases the monomer is believed to be the rate-determining species. Chiral molecules of this type, like benzyl-lithiums, where the metalated carbon centre is a stereochemical probe, give an insight into the involved reaction processes (e.g. substitution, deprotonation). As a result of different charge distributions, planar or pyramidalized lithiated carbon centres are observed – what has significant impacts on further reactions (see Figure 1). We are presenting an experimental charge-density study on the α-lithiated benzylsilane 1. Charge delocalisation into the phenyl-ring and the nature of the C3–Li-contact will be discussed based on the topological analysis of the experimental charge density distribution (see Figure 2).

Figure 1 Potential reaction sites based on the structure of the benzyllithium compound.

Figure 2 Crystal structure of the α-lithiated benzylsilane 1 (left); laplacian distribution in the C4–C3–Si plane (right).

__________ 1. Strohmann, C.; Buchold, D. H. M.; Seibel, T.; Wild, K.; Schildbach, D.; Eur. J. Inorg.

Chem. 2003, 3453. 2. Strohmann, C.; Seibel, T.; Schildbach, D.; J. Am. Chem. Soc. 2004, 126, 9876. 3. Strohmann, C.; Abele, B., C.; Lehmen, K.; Schildbach, D.; Angew. Chem. Int. Ed.

2005, 44, 3136.

1

C4 C3

Si

H8C4-C3-Si plane

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REACTIONS OF SILOLE AND GERMOLE DIANIONS WITH A 1, 4 - DIIMINE Irina S. Toulokhonova, Vitaliy Timokhin, David Bunck, Thomas Mueller, Robert West Organosilicon Research Center, University of Wisconsin, Madison WI 53706 USA

Silole and germole dianions act as strong reducing agents and nucleophiles; silole dianions can be used as sources of stable diradicals. Recently we found that silole dianions undergo novel reductive oxidation reactions with 1,4-butadienes with formation of spiro-adducts, releasing free lithium metal.1

We report here the reaction of dilithiosilole 1 with N,N'-di-tert-butyldiiminoethane (2) in THF leading to formation of spiro-adduct 3, which transforms to 4 upon oxidation (Scheme 1).

Si

Ph4

Li Li+

N

N THFr.t.

Si

Ph4

N N[O] Si

Ph4

N N

O

1 2 3 4But

But

But But ButBut

Scheme 1. Reaction of silole dianion 1 with N,N'-di-tert-butyldiiminoethane 2.

A similar reaction was observed in the interaction of dilithiogermole 5 with diimine 2:

Ge

Ph4

Li Li+

N

N THFr.t.

Ge

Ph4

N N[O]

5 2 6

But

But

But ButGeO

GeO

GeO

Ph4Ph4

Ph4

7 Scheme 2. Reaction of germole dianion 5 with N,N'-di-tert-butyldiiminoethane 2.

A mechanism for these reactions, based on experimental data and theoretical calculations, will be proposed and discussed. 1. I. S. Toulokhonova, D. R. Friedrichsen, N. J. Hill, T. Mueller, R. West, Angew. Chem. Int. Ed., 45, 2578 (2006).

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ANIONIC SPECIES OF TETRAPHENYLPORPHYRIN-SILICON COMPLEXES Kimio Yoshimura, Shintaro Ishida, Soichiro Kyushin Department of Chemistry and Chemical Biology, Graduate School of Engineering, Gunma University, Kiryu, Gunma 376-8515, Japan

Porphyrin-silicon complexes form a unique class of hypercoordinated silicon compounds. We previously reported the molecular structures and spectroscopic properties of several new porphyrin-silicon complexes.1) We report herein synthesis, structures, and properties of anionic species of porphyrin-silicon complexes.

Cyclic voltammograms of tetraphenylporphyrin(TPP)-silicon complexes 1a2) and 1b showed that their first and second reduction waves are reversible, indicating formation of the stable anion species (Table 1). Chemical reduction of 1a and 1b with two equivalents of KC8 in THF afforded the corresponding dianion via their radical anion state.

Molecular structures of [2.2.2]cryptate salts of 2a and 2b were determined by X-ray structural analysis. These salts are solvent-separated ion pairs and their Si–C bond lengths are significantly elongated compared with the corresponding neutral state. This structural and spectroscopic change upon reduction and theoretical studies will be discussed. _________________________________ 1) K. Yoshimura, S. Kyushin, and H. Matsumoto, The 85th Annual Meeting of the Chemical Society of Japan, 2C5-40 (2005). 2) J.-Y. Zheng, K. Konishi, and T. Aida, Inorg. Chem. 1998, 37, 2591.

Table 1. Oxidation-reduction potentials of Si(TPP)R2 and TPP

Compound Eox / V vs. Ag/AgCl2)Ered / V vs. Ag/AgCl1)

1/2E (1)1/2E (2) 1/2E (1) 1/2E (2)

pE

pE

TPP

Si(TPP)Pr2

Si(TPP)MePh

E (2)1/2 1/2E (1)

E (2)1/2 1/2E (1)

1) In THF, TBAP. 2) In CH2Cl2, TBAP.

1.07 1.31

0.69

-1.09-1.45

-1.22-1.82

-1.73 -1.16 0.73

NNN

NSi

R

R'

THFNN

N

NSi

R

R'

1) 2 KC82) [2.2.2]cryptand

2-2{K+ [2.2.2]cryptand}

1a: R = R' = Pr; Si(TPP)Pr21b: R = Me, R' = Ph; Si(TPP)MePh

2a: R = R' = Pr (65%)2b: R = Me, R' = Ph

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THE MECHANISM OF PHOSPHINE DISSOCIATION ON THE SILICON (001) SURFACE Oliver Warschkow1, Hugh F. Wilson1, Nigel A. Marks1, Steven R. Schofield2,3, Neil J. Curson2, Marian W. Radny3, Phillip V. Smith3, David R. McKenzie1, and Michelle Y. Simmons2

Centre for Quantum Computer Technology, School of Physics, The University of Sydney, Sydney, NSW 2006, Australia Centre for Quantum Computer Technology, School of Physics, The University of New South Wales, Sydney, NSW 2052, Australia School of Mathematical and Physical Sciences, The University of Newcastle, Callaghan, NSW 2308. Australia

First-principles surface theory is (arguably) of greatest use when tightly integrated with experimental research: Input from experiment keeps the theory focused on the questions that matter. Theory in turn may provide the key to unlock the many secrets hidden in the experimental data. Our work on the dissociation chemistry of phosphine (PH3) on Si(001) is a case in point. We are interested in this particular system for its relevance in the fabrication of novel quantum electronic devices that require the atomically precise placement of dopant atoms (phosphorus) using STM H-lithography techniques. Extensive STM experiments reveal that the dissociation of PH3 on the silicon surface involves a great number of intermediate species, which appear as distinct features in the images. Based on a comprehensive ab initio survey of conceivable dissociation intermediates and STM image simulations, we are able to structurally characterize three prominent surface features as PH2+H, PH+2H and P+3H species, respectively [1,2]. STM image sequences show these features undergo reactions, which leads to the identification of four additional intermediates (PH+H, P+2H, P and H) and the broad outline of a dissociation mechanism. Transition state calculations are then used to “interpolate” between the observed intermediates to develop the full dissociation path.

_______________________

1 H. F. Wilson, et al., Phys. Rev. Lett. 93 (2004) 226102. 2 O. Warschkow, Phys. Rev. B 72 (2005) 125328. 3 S.R. Schofield, et al. J. Phys. Chem. B 110 (2006) 3173. 4 H.F. Wilson, et al., Phys. Rev. B 74 (2006) 195310.

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SINGLE DANGLING BONDS ON THE SILICON (001) SURFACE: THE INFLUENCE OF SUBSTRATE DOPING ON ATOMIC-SCALE SURFACE DEFECTS AND ADSORBATES Thilo C. G. Reusch1, Marian W. Radny2, Phillip V. Smith2, Oliver Warschkow3, Nigel A. Marks3, Neil J. Curson1, David R. McKenzie3, Michelle Y. Simmons1

Centre for Quantum Computer Technology, School of Physics, University of New South Wales, Sydney, NSW 2052, Australia School of Mathematical and Physical Sciences, The University of Newcastle, Callaghan, NSW 2308. Australia Centre for Quantum Computer Technology, School of Physics, The University of Sydney, Sydney, NSW 2006, Australia

Combining voltage-dependent scanning tunnelling microscopy (STM) experiments and first-principles theory, this presentation will examine how silicon substrate doping can dramatically influence the geometric and electronic structure of certain atomic-scale features on the silicon (001) surface. We consider in detail two specific examples: single phosphorus atoms in the surface (the Si-P heterodimer) and single hydrogen atoms adsorbed onto the surface (the Si-Si-H hemihydride). Both features create a single dangling bond on a surface Si atom and share many other aspects of their electronic structure. The complex response of these species to changes in substrate doping and STM imaging voltage is attributed to charge transfer processes between delocalized states associated with bulk and surface, and localized states associated with the surface species.1, 2, 3, 4

_______________________________

1 M.W. Radny, PV. Smith, T.C.G. Reusch, O. Warschkow, et al., Phys. Rev. B 74, 113311 (2006). 2T.C.G. Reusch et al., Surf. Sci. 600 (2006) 318. 3T.C.G. Reusch, O. Warschkow, et al. Surf. Sci. (accepted for publication). 4T.C.G. Reusch et al., J. Phys. Chem. C (accepted for publication).

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NOVEL SILICON-BASED MEDICINES Galina A. Bikzhanova1, Joyce A. V. Er1, Irina S. Toulokhonova1, Stephen Gately2 and Robert West1

1 Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706; 2 RND Pharmaceuticals, Inc., 14385 Frank LLoyd Wright Blvd., Suite 15, Scottsdale AZ 85260

The introduction of a silicon atom within a known drug molecule can lead to significant changes in drug biological activity and metabolism. Our novel silicon-substituted derivative of well-known non-steroidal anti-inflammatory drug (NSAID) indomethacin demonstrated high biological activity against a pancreatic cancer.

In these studies, we report the synthesis and characterization of lipophilic, silicon-containing derivatives of indomethacin that are selective COX-2 inhibitors with in vitro anticancer activity.1 The graph shows the control of pancreatic cancer cells by one of our silicon-containing drugs compared with the known cancer drug indomethacin. In vivo results will be announced at the silicon symposium.

1

1) G. A. Bikzhanova, I. S. Touokhonova, S. Gately, R. West, Silicon Chem., 3, 209 (2007)

0

50

100

0 0.78 1.56 3.12 6.25 12.5 25 50 100

Drug Concentration, microM

Cel

ls V

iabi

lity,

%

N

OCl

MeMeO

OHN

SiMe

MeMe

N

OCl

MeMeO

OOH

P - 13

THE QUEST FOR SILICONDICARBONYL Si(CO)2 J. Glatthaar*

Institute of Organic Chemistry, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 58, D-35392 Giessen, Deutschland, E-mail: joerg.glatthaar@org.chemie.uni-giessen.de Very recently silicon carbonyl compounds have received new attention. Belanzoni et al. reported a computational study on the structure and stability of Si(CO)4, finding a planar tetra-coordinated silicon atom.1 One entry to this molecule could be the stepwise reaction of CO with Si atoms. In this context the lower carbonylog, Si(CO)2, is a reasonable target. The quest for Si(CO)2 started as early as 1970 with the study by Milligan and Jacox.2 Irradiation of silane in mixed CO / Ar matrices at 10 K gave rise to a strong IR signal at 1899 cm-1, which was assigned to the CO str. of SiCO by Weltner et al.3 in 1977. Upon annealing of the matrix, the absorption due to SiCO decreased and a new IR signal at 1928 cm-1 appeared; it was assigned to Si(CO)2 based on further isotopic labelling studies. In 1990 Schaefer4 et al. questioned this assignment, expecting two strong CO stretching vibrations (s-str. and a-str., intensity ratio 1:2) in the IR spectrum of Si(CO)2. In 2000 Zhou5 et al. studied the reaction of laser ablated Si, Ge and Sn with CO / Ar matrices at 10 K. Upon annealing, two new IR signals at 1928 cm-1 and 1995 cm-1 (10 fold weaker) were assigned to Si(CO)2. In 2004, a more detailed study by Zhou6 et al. reassigned the 1928 cm-1 band to Si2(CO)2; the 1995 cm-1 signal could not be verified. During matrix optimization experiments, an optimal CO / Ar ratio of 1:50 emerged. This ratio is much higher than in earlier experiments, and allowed observation of three silicon carbonyl compounds by IR spectroscopy in the matrix. When a gas stream of silicon atoms was co–deposited with CO / Ar at 10 K, SiCO was formed as the initial reaction product. Annealing to 30 K for 5 – 30 minutes led to the formation of some Si2(CO)2. After annealing 24 hr, the intensity of the IR band of SiCO was strongly decreased and two new IR absorptions (1997 cm-1 and 1912 cm-1; intensity ratio 1:2) appeared. These signals are ascribed to Si(CO)2 on the basis of isotopic labelling experiments and DFT computations.

C C

Si

O O

. .

Si C O + C O.. 30 K∆

24 h

References [1] P. Belanzoni, G. Giorgi, G. F. Cerofolini, A. Sgamellotti, J. Chem. Phys. A 2006,110, 4582-4591; P. Belanzoni, G. Giorgi, G. F. Cerofolini, A. Sgamellotti, Theoret. Chem. Acc. 2006, 108, 293-304. [2] D. E. Milligan, M. E. Jacox, J. Chem. Phys. 1970, 52, 2594-2607. [3] R. R. Lembke, R. F. Ferrante, W. Weltner, J. Am. Chem. Soc. 1977, 99, 416-423. [4] R. S. Grev, H. F. Schaefer III, J. Am. Chem. Soc. 1989, 111, 5687-91. [5] L. Zhang, J. Dong, M. Zhou, J. Chem. Phys. 2000, 113, 8700-8705. [6] M. Zhou, L. Liang, Q. Xu, J. Chem. Phys. Lett. 2004, 121, 10474-10482.

P - 14

THE NATURE OF ELEMENTARY SILICON – A PREFERENTIAL OXOPHILIC ELECTROPHILE? J. Glatthaar,a*Y. P. Lee,b* M. Bahoub a) Institute of Organic Chemistry, Justus-Liebig-University Giessen, Heinrich-

Buff-Ring 58, D-35392 Giessen, Deutschland, E-mail: joerg.glatthaar@org.chemie.uni-giessen.de

b) Dept. Applied Chem. and Inst. Molecular Science, National Chiao Tung University, 1001, Ta-Hsueh Rd., Hsinchu 30010, Taiwan, E-mail: yplee@mail.nctu.edu.tw

The oxophilic character of elementary silicon is reflected in its natural sources, which are containing silicon exclusively bound to oxygen. Artificial siliconoxynitrides1 were astonishingly synthesized through reaction of Si and SiO2 in a nitrogen atmosphere around 1450 oC. The rapid thermal oxidations of Si– or SiO–surfaces in a NO2– or N2O3–ambient are important entries to ultra thin SixOyNz–layers, which are of particular interest in the semiconductor construction. In the gas phase reaction4 of Si atoms with N2O formation of SiO and N2 or alternatively of SiN und NO was observed. These findings support the assumption that silicon does not have an oxophilic character in general. Important factors, controlling the oxophilicity, are the electronic state and the cluster size of silicon. The matrix isolation technique is a suitable tool to study the step by step reactions of clusters or atoms with molecules. NO was inserted into Si2 dimers in Ar at 10 K forming SiNSiO.5 In a more detailed study we have investigated the oxophilic character of Si atoms (triplet ground state) and the ambidentate substrates NO and N2O.6 The experimental results are additionally supported by ab initio calculations and isotopic-labelling experiments. The findings from several co–deposition experiments of Si atoms with NO, N2O2 or N2O in argon matrix at 10 K are in accordance with computations: The first attack of the Si atoms (triplet ground state) always takes place at the N– and not at the O–atom.

N2O NO+Si N

N O Si N O3SiAr, 10 K..

+

Ar, 10 K.

Si reacts with NO under formation of SiNO.5,6 If Si adds to N2O2, C2v symmetric Si(NO)2 is formed through insertion of Si into the NN bond. When Si atoms react with N2O, SiNNO is generated. Only if the matrix is irradiated afterwards with short wavelenght light mainly SiO is formed in all cases. The irradiation of a matrix isolated Si(NO)2 with long wavelength light delivers an even more surprising result. Formation of SiO and N2O or of SiO2 and N2 is not observed. Instead Si(NO)2 is rearranged under generation of a cyclic silylene showing a unique NONO structural motif.

O

ONSi

N ONO

SiN

3Si+ cis-N2O2

Ar, 10 K

. hν, λ = 578 nm..

Ar, 10 K.

Literature [1] C. Brosset, I. Idrestedt, Nature 1964, 201, 1211. [2] M. L. Green, E. P. Gusev, R. Degraeve, E. L. Garfunkel, J. Appl. Phys. 2001, 90, 2057-2121. [3] A. Morales-Acevedo, G. Santana, J. Carrillo-Lopez, J. Electrochem. Soc. 2001, 148, F200-F202. [4] C. Naulin, M. Costes, Z. Moudden, N. Ghanem, G. Dorthe Chem. Phys. Lett. 1993, 202, 452-8. [5] M. F. Zhou, L. Jiang, Q. Xu, J. Chem. Phys. A. 2004, 108, 9521-9526. [6] J. Glatthaar, Y. P. Lee, M. Bahou, Si + NO and N2O2, publication in preparation; J. Glatthaar, Si + N2O, publication in preparation.

P - 15

SiOR

RO

ROX

1X = NH2, SiH3, H Fig. 1 �-Organo- functional silane

COMPUTATIONAL STUDIES ON THE Si–O AND Si–C BOND CLEAVAGE OF �-ORGANOFUNCTIONAL SILANES

Viktoria H. Gessner, Christian Daeschlein, Max A. Schuetz, Carsten Strohmann*

Institute of Inorganic Chemistry, University of Wuerzburg, Am Hubland, D-97074 Wuerzburg, Germany.

Organofunctional alkoxysilanes have found application in a wide variety of

industries as coupling agents, adhesion promoters and scavengers especially in

context with the sol-gel method.1 In alkaline medium these compounds undergo

Si-O bond cleavage, although – from the thermodynamic point of view – the Si-C

bond cleavage should be preferred. However, due to the better stabilization of the

negative charge by the leaving alkoxy group in comparison with the carbanion, the

cleavage of the Si-O bond is favoured in the negative charged penta-coordinated

transition state.2 This kinetic preference can be affected by substituents in �-

position to the silicon centre. We present here computational studies, giving

insight into the proceeding processes (scheme 1). It will be shown that the

transition states of the competing bond cleavages depending on the substituents in

�-position to silicon (fig. 1).

Scheme 1 Comparison of Si–O and Si–C bond cleavage.

1. Strohmann, C.; Schildbach, D.; Auer, D. J. Am. Chem. Soc. 2005, 127, 7968. 2. a) Wong, J.; Sannes, K. A.; Johnson, C. E.; Braumann, J. I. J. Am. Chem. Soc. 2000,

122, 10878; b) Dilman, A. D.; Levin, V. V.; Karni, M.; Apeloig, Y. J. Org. Chem. 2006, 71, 7214.

P - 16

SYNTHESIS OF αααα-FUNCTIONALIZED SILANES VIA LITHIATED AMINES

Viktoria H. Gessner, Carsten Strohmann*

Institute of Inorganic Chemistry, University of Wuerzburg, Am Hubland, D-97074 Wuerzburg, Germany.

�-Functionalized silanes are important compounds in the chemical industry

especially for adhesion promotion, surface modification and polymer crosslinking.

In general, these compounds are synthesized out of the corresponding

(chloromethyl)silanes, which are for themselves rarely available. An alternative

approach to �-functionalized silanes via direct substitution reaction of the

chlorosilane with the �-lithiated amine is restricted, due to the generally limited

availability of the corresponding tertiary methylamines by direct lithiation.1,2 In

the past some examples of methyl-

amines were mentioned, which undergo

direct metallation at their methyl group.3

Here we present the lithiation of the

chiral amine (R,R)-TMCDA (1) and the

subsequent synthesis of the chiral �-

functionalized silane 3.4 In addition, the

formation of the intermediate lithiated

amine 2 and further transformations of

(�-aminomethyl)silanes will be shown.5

Scheme 1 Synthesis of the chiral silane 3 via lithiated (R,R)-TMCDA (2).

1. Strohmann, C.; Abele, B. C. Angew. Chem. 1996, 108, 2515. 2. Katritzky, A. R.; Qi, M. Tetrahedron 1998, 57, 2647. 3. a) Harder, S.; Lutz, M. Organometallics 1994, 13, 5173; b) Schakel, M.; Aarnts, M. P.; Klumpp, G. W. Recl. Trav. Chim. Pays-Bas 1990, 109, 305; c) Strohmann, C.; Gessner, V. H. Angew. Chem. 2007, in press. 4. Strohmann, C.; Gessner, V. H. Angew. Chem. 2007, submitted. 5. Strohmann, C.; Schildbach, D.; Auer, D. J. Am. Chem. Soc. 2005, 127, 7968.

Li1Li2

Li3

N4

N3

N6

N1

N2C1

C11

C21

N5

C2

C3

C4C6

C7

C8C9

C10

C5

C30

C29

C28

C27C26

C25

C24C23

C22

C12C19

C20

C13

C14C15

C16

C17C18

Figure 1 Molecular structure of lithiated (R,R)-TMCDA (23).

NMe2

NMe2

N

NMe2

tBuLi

MeLi

– tBuH

R3SiCl N

NMe2

MeSi

R

RR

(R,R)-TMCDA (1) 2 3

– LiCl

P - 17

STUDIES ON THE DISSOLUTION OF SILICA WITH N-PHENYL-DIETHANOLAMINE.

Ma. Mercedes Salazar-Hernández, Manuel Villanueva García and J. Alfredo Gutiérrez Universidad de Guanajuato, Facultad de Química Noria Alta s/n. Guanajuato, Gto. 36050. México.

Direct synthesis of raw chemicals from silica represents a challenge in the field of silicon chemistry. Several years ago, Rosenheim reported the synthesis of hexacoordinated tris-catechol silicate from silica and catechol in basic medium; later Corriu showed that this anionic complex may be used to obtain organosilanes. More recently, Laine studied the reaction between silica and ethyleneglycol under basic conditions observing the formation of anionic penta- and hexacoordinated alkoxysilanes; in a series of kinetic studies of these reactions it was observed that there is a great influence of the type and quantity of the base employed, that there is a linear dependence on the disolution of the silica with respect to the base concentration and that the rate limiting step is the esterification of the diol with the silanol groups on the silica surface.

In other studies concerning the dissolution of silica with tri-iso-propanolamine in basic medium to yield silatranes, Wongkasemjit and Laine reported too a linear dependence of both the diol and the silica concentrations.

We are studing the reaction of silica with several diols having the same basic framework: X(CH2-CH2-OH)2 (X = O, NtBu, NPh, CH2).We have observed that these diols dissolve the silica under catalytic basic conditions (NaOH, KOH) with good yields (70 to 95%). The best results are obtained with a concentration of the base around 3% and the dissolution of the silica does not ocurr if the base concentration is over 10%; the reaction does not ocurr too when the diol is very basic (diethanolamine and N-methyl-dietanolamine). In the tested reactions, we observe by 29Si NMR the formation of the same type of products (see scheme I). In particular, we have made a kinetic study of the reaction of silica with N-phenyl-diethanolamine by studing the influence of the base concentration, the time and temperature of reaction. For concentrations of the base in the range from 3 to 6% the yield is lowered from 85 to 60%, but it does not influence the ratio of products. For concentrations of the base over 10% the diol is only polymerized without dissolution of the silica. The best yields are obtained at 240°C, 5 degrees below the boiling point of the ligand; at this temperature, 60 minutes of reaction are required for the higer yield (85%) and at 30 and 45 minutes of reaction the yield is lowered and the ratio of products is affected. These results will be discussed. We have isolated and characterized the bis-chelate compound (A, scheme I)

Bibliography

1. A)K. Y. Blohowiak, D. R. Treadwell, B. L. Muller, M. L. Hoppe, S. Jouppi, P. Kansal, R. M. Laine, Chem. Mater., 1994, 6, 2177 b)H. Cheng, R. Tamaki, R. Laine, F. Babonneau, Y. Chujo, D. Treadwell; J. Ame. Chem. Soc., 2000,122, 10063

2. S. Wongkasemijt, R. M. Laine, P. Piboonchaisit, J. Sci. Res. Chula Univ., 2000, 26, 95. 3. A)Salazar Hernández Ma. del Carmen. (2003), “Estudio de la producción de alcóxidos de silicio a partir de sílice”, Tesis de licenciatura

(Ingeniero Químico). Universidad de Guanajuato, México. B)González García, Gerardo. (2004) “Síntesis y Caracterización de Compuestos Neutros de Silicio con un Ligando O1,O2,O3-donador”. Tesis de Licenciatura, Universidad de Cartagena, Colombia. C)Rodríguez Ramírez, Alberto (2005) “Estudio de la Reactividad de la Sílica-Gel frente a Ligantes del Tipo N,N-di-alcanolamina”. Tesis de Licenciatura (QUÍMICO). Universidad de Guanajuato, México

P - 18

LADDER OLIGO- AND POLYPHENYLSILSESQUIOXANES Hiroyasu Seki, Takahiro Gunji, Ken-ichi Suyama, and Yoshimoto Abe. Department of Pure and Applied Chemistry, Tokyo University of science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan. Tel: +81-4-7122-9499, Fax: +81-4-7123-9890, E-mail: gunji@rs.noda.tus.ac.jp Recently, much attention is paid to the synthesis and characterization of ladder-like polysilsesquioxanes (PSQ) as new materials with high thermal stability and electrical insulation. PSQs are often synthesized by the hydrolytic polycondensation of chloro(phenyl)silanes or alkoxy(phenyl)silanes via two-step condensation process. Disiloxanes or cyclotetrasiloxanes are another starting materials because they are simple ladder-structured siloxanes. In this paper, therefore, the synthesis of oligo- and polyphenylsilsesquioxanes will be reported by the heterofunctional condensation of cyclotetrasiloxanes. Tricyclic oligosilsesquioxane (3) was synthesized by the reaction of tetraphenylcyclotetrasiloxanetetraol [PhSi(OH]O]4 (1) with tetrachloro(diphenyl)-disiloxane [Ph2SiCl]2O (2). Compd. 3 was revealed to be ladder oligosilsesquioxane with three eight-membered rings by X-ray crystallography. The heterofunctional condensation of 1 and tetraisocyanato(tetramethyl)cyclotetrasiloxane [MeSi(NCO)O]4 (4) gave highly-soluble PSQ with Mw 13,000-37,000. 29Si NMR spectrum of PSQ showed sharp signals at -61.1--68.3 (∆1/2=2.3 ppm) and -76.1--80.0 ppm (∆1/2=1.9 ppm). The thermogravimetric analysis of PSQ showed a 5% weight loss at 497 oC in air due to a remarkable heat-resistivity of PSQ.

HO

Si O Si

OH

Ph

OSi

HO

OPh

Si

OH

O

PhPh

HO

Si O Si

OH

Ph

OSi

HO

OPh

Si

OH

O

PhPh

Si

Ph

Ph Cl

O

Si

Ph

Ph Cl

Me

Si O Si

NCO

OCN

OSi

Me

OOCN

Si

NCO

O

MeMe

Et3N

Si O Si O Si O Si O Si OOSi O Si

OO Si

OO Si

OO Si

OO Si

OSi

PhMe3SiO

Me3SiOPh Ph

Ph Me Me Ph PhOSiMe3

OSiMe3PhPhMeMe

PSQ

Si O Si O Si O Si

O

Si O Si

O

O Si

O

O Si

O

Ph

Ph Ph

Ph Ph Ph

PhPh

Ph

PhPh

Ph

+ 1) Et3N

21

2) Me3SiCl

3

n

+ 2

4

All-cis isomer

Cis-trans-cis isomer1

P - 19

COMPARING AND COMBINING HYDROPHOBIC AND HYDROPHILIC SILYLATED SURFACES Youlin Pan, Barry Arkles, Yun Mi Kim, Jane Hollenberg, and Gerald L. Larson

Gelest, Inc. 11 East Steel Road, Morrisville, PA 19067 USA

The organosilane approach to the modification of various inorganic surfaces has been successfully practiced for many years. Applications include changing the characteristics of chromatographic columns for both GC and HPLC, proteomics and DNA array technologies, scavenging of metals from reaction mixtures and weather resistant treatments to name but a few. In keeping with the growing interest in the modification of inorganic surfaces for increased hydrophobicity or hydrophilicity with functionalized organosilanes a series of hydrophobic, hydrophilic, and combinations of hydrophobic/hydrophilic organosilanes has been prepared. This study was begun with the goal of understanding the effect of chain length, as well as combinations of systems containing both hydrophobic and hydrophilic moieties on the properties of treated surfaces. The results of the synthesis of the organosilanes and the properties, including contact angle and dispersion characteristics, imparted to the surface by the organosilane will be presented.

P - 20

NEW INSIGHTS INTO Rh(I)-CATALYZED Si-H ACTIVATION AND Si-Si BOND FORMATION Sarah M. Jackson and Lisa Rosenberg*

Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, BC, Canada V8W 3V6. lisarose@uvic.ca

Our interest in the preparation and study of polysilanes led us to reinvestigate the activity of Wilkinson’s catalyst, (Ph3P)3RhCl, 1, in the dehydrogenative homocoupling of secondary silanes, since the oligomeric products of these reactions retain potentially reactive Si-H bonds, useful for further derivatization. Both early and late transition metal catalysts can effect the Si-H activation critical to these Si-Si bond-forming reactions, but late metal catalysts were traditionally considered relatively inactive and unselective for dehydrocoupling, giving large amounts of impurities arising from the competing redistribution of substituents at silicon. We have shown that 1 actually exhibits high activity and chemoselectivity for coupling of secondary silanes, under appropriate conditions.1

The mechanism for late metal Si-Si coupling remains a subject of some debate. We will present our recent efforts to identify intermediates in the silane coupling reactions mediated by 1 and related Rh(I) precatalysts. In particular, stoichiometric reactivity studies point to the importance of reduction of rhodium chloride catalyst precursors to highly reactive rhodium hydride species, and in situ 31P{1H} NMR studies of catalytic mixtures have shown the presence of a common Rh(I) catalyst resting state.

Si

n-Hexn-Hex

Si

n-Hexn-Hex

H

H

1

n-Hex2SiH2

RhPh3P

Ph3P PPh3

ClH Rh

Cl

SiH(n-Hex)2

PPh3

PPh3

– n-Hex2SiHCl– PPh3

RhPh3P

PPh3

H

proposed active catalyst

Si

n-Hexn-Hex

H

H

20.2 mol% 1

– H2(g)Rh

PB

L PA

X

145.8 MHz 31P{1H} (C6D6)44.5, 43.2 ppm

1JRh-Pavg = 243 Hz2JP(A)-P(B) = 150 Hz

proposedcatalyst resting state

1 Rosenberg, L.; Davis, C.W. and Yao, J. J. Am. Chem. Soc. 2001, 123, 5120-5121; Jackson, S.M.; Hughes, C.E.; Monfette, S.; Rosenberg, L. Inorg. Chim. Acta 2006, 359, 2966-2972.

P - 21

DIASTEREOSELECTIVITY IN THE BORANE-CATALYZED HYDROSILYLATION OF α-DIKETONES Adrian Y. Houghton, Andrea E. Kirby, Daniel J. Harrison, Robert McDonald‡, Lisa Rosenberg*

Department of Chemistry, University of Victoria, P.O. Box 3065, Victoria, BC, Canada V8W 3V6; ‡ X-ray Crystallography Laboratory, Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada, T6G 2G2 lisarose@uvic.ca

The electrophilic borane B(C6F5)3 has emerged as a highly active and selective catalyst for the activation of Si-H bonds in a range of silicon-containing substrates.2 We have found this catalyst to be particularly useful in the derivatization of 1,2-dihydridodisilanes, since it exhibits absolute chemoselectivity for Si-H over Si-Si activation in these oligosilanes, under mild conditions and at low catalyst loadings.3

As part of our ongoing exploration of the conformational preferences of the disilanyl unit in a range of cyclic structures, we attempted the borane-catalyzed bis(hydrosilylation) of a range of benzil derivatives by 1,1,2,2-tetraphenyldisilane. Not only do these reactions proceed efficiently and quantitatively at room temperature, they also exhibit high diastereoselectivity, as illustrated in the scheme below.

Si

PhPh

Si

PhPh

H

H

+

B(C6F5)34 mol%

RTO

R'R

O

Si

PhPh

Si

PhPh

O

R'R

O

H H R = R' = Me

R = Me, R' = Ph

R = R' = Ph

meso racemic

86 14

91 9

100 0

This poster will present our spectroscopic and structural characterization of these

product mixtures and recent results indicating that this high diastereoselectivity extends to the analogous reactions of α-diketones with monosilane substrates R3SiH.

2 See, for example: Piers et al. 1999, J. Org. Chem. 64, 4887; Piers et al. J. Org. Chem. 2000, 65, 3090; Piers et al. Org. Lett. 2000, 2, 3921; Piers et al. Tetrahedron 2002, 58, 8247. Gevorgyan et al. J. Org. Chem. 2002, 67, 1936; Rosenberg et al. Organometallics 2005, 24, 1398; Kawakami et al. Macromolecules 2005, 38, 6902; Kawakami et al. Silicon Chem. 2007, 3, 243. 3 Harrison, D.J. M.Sc. Thesis 2005, University of Victoria.

P - 22

MONITORING CATALYTIC DEHYDROCOUPLING OF SILANES IN NON-POLAR SOLVENTS BY ELECTROSPRAY IONIZATION MASS SPECTROMETRY Matthew A. Henderson, J. Scott McIndoe*

Department of Chemistry, University of Victoria, P.O. Box 3065 Victoria, BC V8W3V6, Canada. Email: mcindoe@uvic.ca.

Electrospray ionization mass spectrometry (ESI-MS) is a characterization tool capable of detecting ionic species in minute concentrations directly from a reaction solution, an ability that may be harnessed in the study of organometallic catalysis.1

Studying dehydrosilyl-coupling of di-n-hexylsilane from fluorobenzene using [Rh(COD)(PPh3)2]PF6 with ESI-MS has revealed a rich variety of silicon-containing species of catalytic relevance. Especially prominent is the tris-(triphenylphosphine)rhodium complex at 889 m/z, which forms only in the presence of silane and also as the primary product ion from MS/MS studies of many of the higher m/z species. There is also a significant amount of alkyl scrambling that occurs, an observation previously observed for aryl silanes.2

700 800 900 1000 1100 12000

50

100

% In

tens

ity

m/z

735.3RhCOD(PPh3)2

+

889.4Rh(PPh3)3

+

_________________________________ 1 M.A. Henderson, J.S. McIndoe, Chem. Commun. 2006, 2872-2874. 2 L. Rosenberg, Macromol. Symp. 2003, 196, 347-353.

P - 23

Author Index

Abe, Yoshimoto C-21

Baines, Kim C-14

Braddock-Wilking, Janet P-5

Bradley, Chris C-31

Cervantes, Jorge P-4

Däschlein, Christian P-6, P-7, P-8

Eichler, Barret P-2

Eliseeva, Tatiana C-28

Fink, Mark C-15

Ganachaud, Francois I-5

Gessner, Viktoria P-16, P-17

Glatthaar, Joerg C-9, P-14, P-15

Gonzalez-Garcia, Gerardo C-29

Henderson, Eric C-4

Henderson, Matthew P-23

Hessel, Colin C-6

Interrante, Leonard C-26

Jackson, Sarah P-21

Kafafi, Zakya PL-1

Kanner, Bernard P-1

Kawakami, Yusuke I-8

Kirby, Andrea P-22

Korgel, Brian C-17

Kyushin, Soichiro I-1

Lambert, Joseph C-25

Lee, Myong Euy C-1

Leigh, Willie C-8

Lewis, Kenrick C-10

Marciniec, Bogdan PL-3

Moiseev, Andrey C-7

Pagenkopf, Brian I-2

Pan, Youlin P-20

Perutz, Robin I-6, I-7

Pichaandi, Kothanda Rama P-3

Pouget, Emmanuel C-30

Rollings, De-ann C-32

Sabo-Etienne, Sylviane I-7, I-6

Salazar-Hernandez, Ma. Mercedes P-18

Saxena, Anubhav C-19

Seki, Hiroyasu P-19

Sieburth, Scott C-13

Steel, Patrick I-3

Strohmann, Carsten C-12

Stüger, Harald C-24

Tacke, Reinhold C-27

Thompson, David C-20

Tilley, Don C-23

Tomasik, Adam C-3

Toulokhonova, Irina P-9

Unno, Masafumi C-11

Veinot, Jon I-4

Warschkow, Oliver C-16, P-11, P-12

West, Robert C-2, P-13

Wieder, Noah C-22

Wolkow, Robert PL-2

Yoshimura, Kimio P-10

Zelisko, Paul C-18

Zhang, Xiaoming C-5

Sponsors of the 40th Silicon Symposium

38th Silicon Symposium

University of Victoria:• Vice President - Research• Department of Chemistry• Faculty of Science