cobalt(ii) and nickel(ii) complexes with n 2 o 2...

Hindawi Publishing CorporationJournal of Inorganic ChemistryVolume 2013 Article ID 104979 11 pageshttpdxdoiorg1011552013104979

Research ArticleSynthesis Characterization and Electrochemical Behaviour ofCobalt(II) and Nickel(II) Complexes with N

2O2

Chelating Ligand441015840-(Biphenyl-441015840-diyldinitrilo)dipentan-2-one

Lakhdar Sibous1 Embarek Bentouhami1 and Mustayeen Ahmed Khan2

1 Laboratoire de Chimie Ingenierie Moleculaire et Nanostructures Departement de Genie des ProcedesFaculte de Technologie Universite Ferhat Abbas 19000 Setif Algeria

2 Chimie de Coordination Faculte de Pharmacie Universite drsquoAngers 16 boulevard Daviers 49045 Angers Cedex 01 France

Correspondence should be addressed to Mustayeen Ahmed Khan mustayeenkhanuniv-angersfr

Received 14 April 2013 Revised 30 June 2013 Accepted 1 July 2013

Academic Editor Guido Crisponi

Copyright copy 2013 Lakhdar Sibous et alThis is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

441015840-Diaminobiphenyl reacts with 24-pentanedione in absolute ethanol in a molar ratio 1 2 to form mainly the product of [1 +2] condensation 441015840-(biphenyl-441015840-diyldinitrilo)dipentan-2-one (H

2L) The Schiff base was used as tetradentate chelating ligand

to coordinate CoII and NiII chlorides leading to complexes where the ratio of metal ligand was found to be 2 1 or 2 2 All thesynthesized products were characterized by elemental analysis infrared electronic and mass spectroscopy 1H NMR and DSCThe electrochemical behaviour of the ligand and its complexes in DMF is also investigated

1 Introduction

Aromatic Schiff base compounds have significant importancein the fields of coordination chemistry and material sciencesbecause they are potentially capable to form stable complexeswith different metal ions [1ndash3] Schiff base ligands that havesolvent dependent UV-vis spectra (solvatochromicity) can besuitable nonlinear optical (NLO) active materials [4] Theycan be usefulmaterials in solid phase extraction and synthesisof ion-selective electrodes for the determination of anions inanalytical samples [5ndash7] Schiff base ligands can also be usedin enantioselective [8] and regioselective [9] ring opening ofepoxides enantioselective epoxidation of alkenes [10] andasymmetric oxidation of methyl phenyl sulphide [11]

Transition metal complexes with oxygen and nitrogendonor Schiff base ligands are of particular interest [12] be-cause of their ability to possess unusual configuration beingstructurally labile and their sensitivity to molecular environ-ment [13] Schiff base ligands can accommodate differentmetal centres involving various coordination modes therebyallowing successful synthesis of homo- and heterometalliccomplexes with varied stereochemistry [14] This feature isemployed formodelling active sites in biological systems [15]

Additionally these complexes have wide applications such asantibacterial and antifungal agents [16]

Recently much research on macrocyclic complexes havebeen focused on species containing the first-row transitionmetal ions and tetradentate ligands [17] The formation ofmacrocyclic complexes depends significantly on the dimen-sion of internal cavity on the rigidity of the macrocycleson the nature of its donor atoms and on the complexingproperties of the anion involved in the coordination [18]Theinterest in such species stems from the application of thesecomplexes ranging from modelling the active sites of manymetalloenzymes [19] to hosting and carrying small molecules[20] or catalysts [21 22]

In continuation of our investigation on the ligatingproperties of N

2O2Schiff base ligands [23] we report herein

the synthesis and characterization of 441015840-(biphenyl-441015840-diyldinitrilo)dipentan-2-one (H

2L) derived from the con-

densation of 441015840-diaminobiphenyl with 24-pentanedionein a molar ratio 1 2 and its two types of binuclear Co(II)and Ni(II) complexes These products were characterizedby elemental analysis IR UV-vis spectroscopy and MS 1HNMR and DSC as well as cyclic voltammetry

2 Journal of Inorganic Chemistry

O O

NNCH3

EtOH

O O

CH3

CH3

H3C

H3C

H3C

NH2H2N

H2L

24 h60∘C

+

Figure 1 Synthetic route of the Schiff base ligand H2L

2 Experimental

21 Materials and Methods All materials and solvents wereanalytical reagent grade The compounds 441015840-diaminobi-phenyl and 24-pentanedione were commercial samples fromAldrich and purified by standard procedures Their puritywas determined by thin layer chromatography (TLC) ordry column ldquoflashrdquo chromatography (DCFC) (SiO

2 Merck-

Kieselgel 60H) All metals were hydrated chlorides and usedas received Reactions of 441015840-diaminobiphenyl with 24-pentanedione were carried out using ethyl alcohol-reactantsin sealed Rotaflo-tapped Pyrex ampoules (50 cm3) Crudereaction productmixture was examined by TLC and individ-ual components were separated by filtration Further purifi-cation where necessary was achieved by TLC or repeatedDCFC

22 Measurements Products were examined by IR andrecorded with a Perkin-Elmer 1000 series FT-IR spectropho-tometer using KBr disks UV-vis spectra were obtainedin DMF with a UNICAM UV-300 spectrophotometer 1HNMR spectra of the ligand and the diamagnetic complexeswere recorded on a Jeol GSX WB spectrometer instrumentoperating at 270MHz and the chemical shifts to low fieldof the reference are designated positive and given in ppmusing tetramethylsilane (TMS) as external reference NMRsamples were run as solutions in DMSO-D

6 Mass spectra

were recorded on a Bruker Daltonics Data Analysis 31spectrometer using electron impact (EI) conditions Elemen-tal analysis was carried out with an EL III-ELEMENTARMelting points were determined with a Kofler bench andare uncorrected Differential scanning calorimetry (DSC)diagramswere recorded in the 25ndash400∘C range with aMettlerDSC 822e unit with the help of Mettler Toledo STARe SW810 System software the heating rate was 10∘C per minuteall measurements were made in 40mm3 closed Al crucibles

Electrochemical measurements were recorded on aRadiometer VOLTALAB 32 (DEA 332 type) the workingelectrode was a 2mm diameter Pt rotating disk and theauxiliary electrode a Pt wire A saturated calomel electrode

was used as the reference electrode and measurementswere carried out at room temperature DMF was used assolvent and the ionic strength maintained at 01mol Lminus1 withBu4NClO

4(TBAP) as supporting electrolyte The concentra-

tions of species were in the 2510minus3 to 510minus3mol Lminus1 rangeThe sweep speed was 100mV sminus1 unless otherwise indicated

23 Preparation of the Ligand 441015840-(Biphenyl-441015840-diyldinitri-lo)dipentan-2-one TheSchiff base ligand (shown in Figure 1)has already been synthesized [24] In our work howeverthe same product is prepared using a different procedurecompared to either the previous one or that of literature[25] which reported theNMR characterization of120573-diketoneSchiff bases in CDCl

3 Here 441015840-Diaminobiphenyl and 24-

pentanedione were mixed in absolute ethanol and sealedin vacuo in a dry Rotaflo-tapped Pyrex tube (ca 50 cm3)as follows to a solution of 441015840-diaminobiphenyl (075 g081mol Lminus1) was added a solution of 24-pentanedione(082 g 163mol Lminus1) in a 1 2 molar ratio The mixture washeated in vacuo at 60∘C during 24 h to give yellow solutionand pale yellowprecipitateThe volatilematerial was removedin vacuo by condensation into a trap cooled to minus196∘C andidentified as ethanol by IR spectroscopy The residue (117 g)which remained in the tube was washed out using freshethanol and then extracted with the same solvent (3 times 10mL)to give after removal of the solvent from the filtrate underreduced pressure the ligand H

2L that is formed from the

[1+2] condensationThis product was furthermore subjectedto dry column ldquoflashrdquo chromatography (DCFC) using ethanolas eluent and its yield was almost quantitative (83)

24 Preparation of the Co(II) and Ni(II) Complexes All thecomplexes were prepared using the same synthetic pathwaydescribed in literature [26 27] by mixing in absolute EtOHamounts of ligand H

2L (02 g 01mol Lminus1) and hydrated

cobalt and nickel chlorides in 1 1 or 1 2 molar ratio Afterstanding under reflux conditions for 16 h the mixture waskept overnight at room temperature The complex whichprecipitated was removed by filtration washed several times

Journal of Inorganic Chemistry 3

Table 1 Main analytical data for the ligand and its complexes in the solid state

Compound Color Yield () Mp (∘C) M+ Elemental analysis found (calcd) ()C H N

H2L Yellow 83 134 3482 7568 (7583) 714 (694) 775 (804)([Co(H2L)]

4+)2 Blue 65 gt260 8147 6478 (6486) 621 (593) 699 (687)([Ni(H2L)]

4+)2 Yellow 79 gt260 8142 6464 (6490) 616 (594) 704 (688)[(CoCl2)2(H2L)]

4+ Green 60 gt260 6081 4372 (4345) 425 (397) 475 (460)[(NiCl2)2(H2L)]

4+sdot2H2O Yellow 58 gt260 mdash 4101 (4118) 430 (408) 465 (436)

Table 2Mass spectrometry data of H2L ([Co(H2L)]4+)2 [(CoCl2)2

(H2L)]4+ and ([Ni(H2L)]

4+)2 in the solid state

Compound 119898119911 Assignment Abundance()

H2L3482 M+ 783053 (C20H21N2O)

+ 202482 (C17H16N2)

+ 10

([Co(H2L)]4+)2

8147 M+ 106864 (C37H34N3O3Co2)

7+ 273922 (C21H21N2O2Co)

5+ 912411 (C9H14N2O2Co)

5+ 17

[(CoCl2)2(H2L)]4+

6081 M+ 105017 (C22H24N2O2Co2Cl)

5+ 183801 (C17H16NOCoCl2)

3+ 632331 (C11H12NOCo)3+ 84

([Ni(H2L)]4+)2

8142 M+ 135993 (C36H34N3O2Ni)

5+ 163931 (C21H22N2O2Ni)

5+ 933161 (C15H17N2O2Ni)

5+ 15

with EtOH (3 times 10mL) and dried under vacuum Theirpurity was verified using thin layer chromatography (TLC)and CH

2Cl2EtOH (3 7 vv) as eluent and were shown in

any case to contain only one component (119877119891052) These

products were again subjected to (DCFC) to afford the 1 1or 1 2-complexes in good yields (58ndash79) (Table 1)

3 Results and Discussion

31 Synthesis and Characterization The synthesized Schiffbase H

2L (Figure 1) was used as tetradentate ligand to form

the four complexes reported in this account This compoundemploys two imine nitrogen and two oxygen atoms to bindthe metals All complexes were synthesized in good yield byreacting H

2L with hydrated metal chlorides CoII and NiII in

a molar ratio 1 1 or 1 2 using ethyl alcohol as solvent at60∘C Analytically pure solid compounds were obtained inall cases as indicated by mass spectrometry and elementalanalysis They are air stable and are of higher melting pointsthan the parent ligand The higher melting points of thesecomplexes (gt260∘C) compared to those of the ligand (134∘C)can be taken as an evidence for the bonding to the cobalt(II)or nickel(II) ions with chelate rings formation [28] This

last information together with the presence of the parention peaks (M+) in the mass spectra of three complexes inthe solid state are consistent with the proposed molecularformulae and the (metal-ligand) ratio is compatible with the2 1 or 2 2 form depending on the molar ratio of the mixedreactants used during the preparation The main analyticaldata obtained for the ligand and its complexes at the solidstate is collected in Table 1

32 Mass Spectra of the Ligand and Its Complexes Theinformation about the (metal-ligand) ratio was obtainedfrom mass spectrometry of the three complexes exam-ined in the solid state which reveal that the complexesare binuclear compounds The molecular weights of theseproducts were determined using electron impact (EI) con-ditions which gave the parent ion peaks M+ at mz 81476081 and 8142 These values are assigned respectively tothe species [([Co(H

2L)]4+)

2]+ ([(CoCl

2)2(H2L)]4+)+ and

[([Ni(H2L)]4+)

2]+ (Figures 2(b) 2(c) and 2(d)) All MS

data of the metal complexes which are compiled in Table 2show similar fragmentation pattern and exhibit ion peaksattributed to (M+ + 1) and (M+ + 2) Furthermore promi-nent breakdown peaks corresponding to loss of chlorineatoms were also observed in case of [(CoCl

2)2(H2L)]4+ and

[(NiCl2)2(H2L)]4+sdot2H

2O complexes In addition the ligand

H2L was also examined and its mass spectrum gave the

molecular ion at mz 3482 as shown in Figure 2(a) andTable 2 These results agree with the proposed structures andare mentioned in Table 1 as well as in Table 2

33 Infrared Spectra of the Ligand and the Complexes Acomparative study of the IR spectral data of the reportedcomplexes with that of the uncomplexed ligand gives mean-ingful information regarding bonding sites of the ligandmolecule with metal cations In fact the Schiff bases suchas H2L contain a proton adjacent to the carbonyl group

and consequently can undergo in solution an equilibriumbetween three tautomers as indicated in Figure 3 Structuralstudies about this type of Schiff base ligands have indicatedthat they exist predominantly as the ketoamine tautomerIII This determination is first based upon IR spectra usingbands in the 3200ndash3500 cmminus1 region assigned to the ](NndashH)stretching vibrationHowever infrared spectroscopymay notbe a sufficient tool because it is difficult to distinguish betweena ](OndashH) of a coordinated enolimine tautomer II and a ](NndashH) of a coordinated ketoamine tautomer III [29] The secondway is 1H NMR by using the chemical shifts in the 120575 84ndash126 ppm range [24 30]


(a) (b)

(c) (d)

Figure 2 Mass spectra of H2L (a) ([Co(H

2L)]4+)

2(b) [(CoCl

2)2(H2L)]4+ (c) and ([Ni(H

2L)]4+)

2(d)

Table 3 Main spectroscopic IR data for the ligand (solid state) and its complexes (CH2Cl2 solution) For UV-visible both in DMF solution

Compound Infrared (cmminus1) UV-vis (DMF solution)](NndashH) ](OndashH) ](C=N) ](C=O) ](CndashO) ](MndashO) ](MndashN) 120582max (nm)

H2L mdash mdash 1570 s 1610 vs mdash mdash mdash 351([Co(H2L)]

4+)2 3296 b mdash 1557 m 1626 s mdash 516 w 473 w 299 610 678([Ni(H2L)]

4+)2 3293 m mdash 1551 m 1619 s mdash 514 w 437 w 302[(CoCl2)2(H2L)]

4+ 3289 m mdash 1550 m 1625 s mdash 515 w 435 w 303 608 674[(NiCl2)2L]

2+sdot2H2O mdash 3378 b 1548 m mdash 1370 m 514 w 448 w 300

vs very strong m medium b broad w weak

The main IR bands for the free ligand H2L recorded as

KBr disks and its complexes in CH2Cl2solution with their

tentative assignments are given in Table 3 The free ligandexhibits bands at 1610 and 1570 cmminus1 regions due to thestretching vibrations ](C=O) and ](C=N) respectively Thewavenumber of the keto stretching vibration band is typicalof the presence of hydrogen bonding between this oxygen

atom and the hydrogen atom from the imino functionalgroup [31] The low energy position of the ](C=N) bandcould be attributed to its involvement in conjugation with thearomatic system The medium bands at 2991 and 3051 cmminus1not mentioned in Table 3 are assigned to the aliphatic andthe aromatic protons These data indicate that the free ligandexists mainly in the ketonic form in the solid state The


NNO O

NN

O

OHHOII

Enolimine

IKetoimine

KetoamineIII

NHHN O

CH3

CH3

CH3

CH3

CH3

CH3

H3C

H3C

H3C

H3C

H3C

H3C

Figure 3 Ketoimine form of the Schiff base ligandH2L in solid state

and its ketoamine or enolimine tautomer form when dissolved inorganic solvent

appearance of only one band for each of the C=O and C=Ngroups indicates the symmetrical nature of the free ligandH2LThe IR spectra of [(CoCl

2)2(H2L)]4+ ([Co(H

2L)]4+)

2and

([Ni(H2L)]4+)

2complexes show the very strong band due

to ](C=O) shift to higher wavenumbers (1626 1619 and1625 cmminus1 resp) but there was a new medium band insteadin case of [(NiCl

2)2L]2+sdot2H

2O complex which loses 2H and

two positive charges in solution This band was observed at1370 cmminus1 and assignable to ](CndashO) On the other hand the](C=N) bands were shifted to lower frequencies as comparedto the position in the ligand and occur within 1548ndash1557 cmminus1range due to the conjugate system ndashC=NndashC=Cndash indicatingthe keto form of the ligand even in the presence of themetal ion [32 33] Additional evidence for coordination ofnitrogen and oxygen atoms is the appearance of the new](MndashN) and ](MndashO) bands in the 435ndash448 cmminus1 and 514ndash516 cmminus1 regions respectivelyThese observations are in goodagreement with earlier reported results [34ndash36]

Furthermore the aliphatic and aromatic vibration pro-tons are not greatly affected upon complexation In the 3200ndash3500 cmminus1 region only the complex [(NiCl

2)2L]2+sdot2H

2Opre-

sents a broad band around 3378 cmminus1 corresponding to theOndashH stretching vibration band of water molecules In allother spectra the shape of the band is similar indicating theabsence of hydrogen bonding Accordingly the ligand acts asa dibasic tetradentate ligand coordinating to the Co2+ or Ni2+ions and producing the 2 2 (metal-ligand) complexes viathe ketooxygen and azomethine-nitrogen atoms However incase of the 2 1 compounds the complexation to the Co2+

was via the ketooxygen and azomethine-nitrogenwhile to theNi2+ was found to be via the enolatooxygen and azomethine-nitrogen atoms

34 Electronic Spectra of the Ligand and Its Co(II) and Ni(II)Complexes Electronic spectra of the ligand and its metalcomplexes have been measured in DMF and the numericaldata of the band maxima (120582max) are presented in Table 3In general the UV-visible region of the electronic spectraof all the products was dominated by intense band which isassigned to a 120587-120587lowast transition associated with the azomethinelinkage [37]

The ligand and the complexes exhibit intense bandsin the high energy region in the 299ndash351 nm range (120576 =5518ndash32444 Lmolminus1 cmminus1) which can be assigned to LMCT(ligand-metal charge transfer) bands [38] The electronicspectra show that absorption bands of the two nickel(II)complexes occur below 600 nm A lack of any electronictransition at longer wavelengths is consistent with the squareplanar geometry of Ni(II) compounds However in the caseof cobalt(II) complexes the d-d transitions were observedin the 608ndash678 nm range The bands located at 610 nm (120576 =240 Lmolminus1 cmminus1) and 678 nm (120576 = 3671 Lmolminus1 cmminus1) areattributed to ([Co(H

2L)]4+)

2 while those at 608 nm (120576 =

363 Lmolminus1 cmminus1) and 674 nm (120576 = 6179 Lmolminus1 cmminus1) areassigned to [(CoCl

2)2(H2L)]4+ These bands usually corre-

spond to a tetrahedral environment around Co2+ ion [31]The obtained values are of particular importance since

they were highly dependent on the geometry of themoleculeIt is known that the transitions from a square planar structureto a deformed tetrahedral one leads to a red shift of absorp-tion in the electronic spectra [39]

Thus the smaller value of the wavelength of the bandcorresponding to the transitions is resemblance between thegeometry of the complex and that of square planar complex

35 1H NMR Spectra of the Ligand and Its Ni(II) ComplexesComparison of 1H NMR spectral data of the ligand H

2L

and the diamagnetic Ni(II) complexes recorded in DMSO-D6solution as indicated in Figure 4 further supplements the

conclusion drawn from IR dataThe aromatic protons of the ligand (Figure 4(a)) showed a

multiplet at 120575 72ndash75 ppm assigned to biphenyl protons anda singlet at 120575 1243 ppm typical for hydrogen bonded NndashHorOndashHwhich disappeared in presence ofD

2OThe spectrum

exhibits also a singlet at 120575 51 ppm due to the ethylenic(CH=C) protons In addition the singlet at 120575 195 ppm wasattributed to the methyl groups These peaks are in goodagreement with the presence of H

2L in solution either in

its ketoamine form (tautomer III) or in its enolimine form(tautomer II) [29 30 40]

In case of the ([Ni(H2L)]4+)

2complex no changes were

observed in the 1HNMR spectrum (Figure 4(b)) concerningthe absorption previously indicated at 120575 1243 ppm in theligand In solution of DMSO-D

6 this proton resonates after

complexation at 120575 1245 ppm without any deprotonationwhich means that the ligand was in its ketoamine form(tautomer III) It should be noted that this peak cannot be


(ppm)

DMSO

14 12 10 8 6 4 2

(a)

(ppm)12 10 8 6 4 2 0

(b)

(ppm)12 10 8 6 4 2 0

(c)

Figure 4 1H NMR spectra of H2L (a) ([Ni(H

2L)]4+)

2(b) and [(NiCl

2)2L)]2+ (c) in DMSO-D

6solution and in the 120575 0ndash13 ppm range

observed if the complex does not exist in a tautomeric form(case of the solid state) All other signals were very similarand no significant shifts were observed

However in case of the [(NiCl2)2L]2+sdot2H

2O complex in

solution the difference becomes more important since thesignal which appeared in the free ligand at 120575 1243 ppmcompletely disappeared in the spectrum (Figure 4(c)) Thisindicates that during complexation the ligandH

2L in its eno-

limine form (tautomer II) undergoes deprotonation followedby coordination to the Ni2+ ions All the remaining signals inthis complexwere very similar to that of the ligand and appearnearly at the same positions

Apparently the single peak which is located in the 120575 51ndash52 ppm range in the spectra of the ligand H

2L and the

two Ni(II) complexes and attributed to the ethylenic (CH=C)proton was found to be most useful indicating that everyproduct is present as individual isomer

36 Thermal Analysis In order to give more insight into thestructure of the ligand and its complexes the thermal studiesof these compounds have been carried out using DSC tech-nique where the diagrams of these products show significantdifferences between the ligand H

2L and its complexes The

decomposition of all these species occurs at temperatureshigher than 340∘C and is generally followed by severalexothermic peaks due to this phenomenon

The DSC diagram of the ligand shows two endothermicpeaks occurring at ca 140 and 340∘CThe first one either cor-responds to themelting of the molecule or to the coordinatedwater and the second one is followed by several exothermicpeaks due to the chemical decomposition of the molecule

The2 1 and 2 2 (cobalt-ligand) complexes donot containany hydrated or adsorbed water molecules They are verythermally stable and show weak endothermic peaks at 360ndash390∘C range On the opposite side the DSC diagram of the2 1 (nickel-ligand) complex shows many peaks at the 110ndash130∘C range and is due to loss of water molecules while the2 2 (nickel-ligand) compound shows a very weak endothermat 190∘C followed with a well-resolved endotherm at 380∘C

37 Proposed Structures for the Co(II) and Ni(II) ComplexesDepending on the IR 1H NMR and mass spectra thesuggested structures are given in Figures 5(a) and 5(b)showing how the complexes should be either in solutionor in the solid states respectively The Schiff base H

2L

acts as a tetradentate ligand via the ketoimine tautomer


ONHHN

O

NHHNOO

MM

ONHHN

OCoCo

Cl Cl ClCl

NNO O

Cl ClNi

Cl ClNi

H3C

H3C

H3C

H3C

H3CH3C

H3C

CH3

CH3

CH3

CH3

CH3

H3CCH3

CH3

CH3

middot2H2O

M = Co or Ni

+

+

+

+

+

+

+

+

+

++

+

+ +

(a) The complexes in solutions

ONHHN

O

NHHNOO

MM

ONHHN

O

ClCl ClCl

MM

H3C

H3C

H3C

H3C

H3C

H3C

CH3

CH3

CH3

CH3

CH3

CH3

M = Co or Ni with 2H2O in case of2 1 [metal-ligand] complex

+

+

+

+

+

+

+

+

++

+ +

(b) The complexes in the solid state

Figure 5 Proposed structures for CoII and NiII complexes either in solution (a) or in solid state (b)

according to a symmetrical configuration This geometryremains unchanged after complexation

The cobalt(II) and nickel(II) complexes exhibit differentstructures These species are binuclear complexes and thecoordination of the metal cation is linked through N(imino)and O(keto) atoms The two cobalt(II) compounds presenta distorted tetrahedral geometry while the two nickel(II)complexes exhibit a typical square planar surrounding [3940] In addition two water molecules appear in case of 2 1[Ni(II)L] (as indicated by infrared spectroscopy and thermalanalysis)

38 Electrochemical Behaviour of the Ligand and the Com-plexes The main electrochemical results of the examinedligand as well as its complexes are summarised in Table 4 andsome representative voltammograms are shown in Figure 6The electrochemical behaviour in the whole range investi-gated (Figures 6(a)ndash6(e)) showed a pattern that could beconsidered as the sum of the individual responses

The voltammetric response of the ligand H2L in the ndash18

to +18 V range (Figure 6(a)) shows three waves in the anodicside with peak potential values of +056 +087 and +120Vwhich can be ascribed to the irreversible oxidations of theligand and one cathodic peak at ndash097V resulting from thereduction of the imino group [40] During reduction sweepthe cyclic voltammogram shows only one quasireversiblecathodic peak at +076V associated with the reduction of theoxidised species of H

2L (oxidation of the azomethinemoiety)

[41]

When the speed sweep is varying (ie 500 300 200100mVsminus1 resp) the curve 119894pa (at +076V) as a functionof speed square root is a curve line (not shown) and thecurve 119864pa = 119891(log V) is a straight line These results showthat this reduction peak corresponds to a diffusion controlledquasireversible system [42]

The cyclic voltammograms of the four complexes exhibitoxidation and reduction metal centred processes as forcomplexes previously published [43] On the cathodic sidethe cyclic voltammograms of the 2 2 and 2 1 (cobalt-ligand)complexes (Figures 6(b) and 6(c)) show a similar reoxidationpeak at ndash010V and two cathodic peaks at ndash114V and ndash117 Vattributed to ([Co(H

2L)]4+)

2and [(CoCl

2)2(H2L)]4+ respec-

tively The cathodic peaks at ndash114 and ndash117 V correspondto the reduction of complexed CoII into Co0 [44] FinallyCo0 is oxidised to give back coordinated CoII (anodic peak atndash010V) When performing successive sweeps the intensityof the peak at ndash114V diminished and in the meantimemetallic cobalt was formed

In case of nickel(II) complexes these products in additionto the ligand peaks undergo reduction processes located atndash154V and ndash118 V (Figures 6(d) and 6(e)) and attributedto the 2 2 and 2 1 [nickel-ligand] complexes respectivelyThese peaks correspond in fact to the reduction of NiII intoNi0 and the reoxidation of Ni0 in case of the 2 2 compoundis observed at ndash011 V while that of 2 1 complex is located at+011 V These values agree with those previously describedfor nickel complexes in the same solvent [45]


000

002

004

006

008

1 205 150

minus004

minus002

minus2 minus15 minus1 minus05

i(m

Amiddotcm

minus2)

E (V versus SCE)

(a)

002

004

006

008

010

012

15 20 05 1minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(b)

002

004

006

008

10 21505

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(c)

002

004

006

008

0 1 15 205minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(d)

050 1 215

002

004

006

008

minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(e)

Figure 6 Representative cyclic voltammograms in DMF at room temperature (ionic strength 01mol Lminus1 Bu4NClO

4 119894 in mA V =

100mVsminus1) of H2L (a) ([Co(H

2L)]4+)

2(b) [(CoCl

2)2(H2L)]4+ (c) ([Ni(H

2L)]4+)

2(d) and [(NiCl

2)2L]2+ (e) in the ndash180 to +180 range


Table 4 Voltammetric results at room temperature (26 plusmn 1∘C) in DMF ionic strength 01mol Lminus1 (TBAP) results in V versus SCE sweepspeed 100mVsminus1 119864pa anodic 119864pc cathodic

Compound 119864pa1 119864pa2 119864pa3 119864pa4 119864pc1 119864pc3 119864pc4 Δ119864pa

11986412

b

H2L mdash +056 +087 +120 minus097 +076 mdash 011 0925([Co(H2L)]

4+)2 minus010 +062 +105 +112 minus114 +068 +125 037 1235([Ni(H2L)]

4+)2 minus011 +073 +117 +135 minus154 +065 +120 052 1430[(CoCl2)2(H2L)]

4+minus010 +059 +092 +131 minus117 +068 +117 024 1040

[(NiCl2)2L]2+sdot2H2O +011 +054 +094 +147 minus118 +066 +119 028 1080

aΔ119864p = 119864pc minus 119864pa

b11986412= 05Δ119864p + 119864pa

Furthermore a linear dependence which was observedbetween 119864p and 119894p as the voltage scan rate (V) increased(ie 100 200 300 500mVsminus1 resp) indicates a diffusioncontrolled quasireversible electrode exchange reaction Thecurve119864pa for the oxidation peak potential at ndash011 V or +011 Vof the 2 2 or the 2 1 [nickel-ligand] complex respectively asa function of log V (not shown) gave a straight line parallelto the horizontal 119909-axis and does not depend upon thesweep speed In addition the ratio 119894pc119894pa was independentof scan rate and equal to unity for scan rates changing from100mVsminus1 to 1 Vsminus1

These results are in good agreement with the above pro-posed structures

4 Conclusion

In summary the Co(II) and Ni(II) complexes were syn-thesized using the binucleating tetradentate chelating agentformed by the condensation of 441015840-diaminobiphenyl with24-pentanedione IR 1H NMR mass spectral data andelemental analysis are used to confirm the structure of theSchiff base H

2L The mass spectra are also used to proof the

stoichiometry and formulation of the complexes Based ontheUV-vis spectral data a square planar geometry is assumedfor Ni(II) complexes while the Co(II) compounds presenta distorted tetrahedral geometry In addition they are moreeasily oxidizable in the cyclic voltammetry and also showa quasireversible behavior Finally these products could beinvestigated in the near future in the fields of microbiologyand electrocatalysis

Acknowledgment

The authors are indebted to and thank the Pharmacy Depart-ment (U F A Setif) for the general facility projects andfinancial support

References

[1] A L Vance N W Alcock J A Heppert and D H Busch ldquoAnoctahedral template based on a new molecular turn synthesisand structure of a model complex and a reactive diphenolicligand and itsmetal complexesrdquo Inorganic Chemistry vol 37 no26 pp 6912ndash6920 1998

[2] R Ziessel ldquoSchiff-based bipyridine ligands Unusual coordi-nation features and mesomorphic behaviourrdquo CoordinationChemistry Reviews vol 216-217 pp 195ndash223 2001

[3] N Alizadeh S Ershad H Naeimi H Sharghi and M Sham-sipur ldquoSynthesis of a new naphthol-derivative salen and spec-trophotometric study of the thermodynamics and kinetics of itscomplexation with copper(II) ion in binary dimethylsulfoxide-acetonitrile mixturesrdquo Polish Journal of Chemistry vol 73 no 6pp 915ndash925 1999

[4] A A Alemi and B Shaabani ldquoSynthesis and characterization ofa schiff base of p-tert-butylcalix[4]arene and its complex withcopper(II)rdquo Acta Chimica Slovenica vol 47 no 3 pp 363ndash3692000

[5] P Buhlmann E Pretsch and E Bakker ldquoCarrier-based ion-selective electrodes and bulk optodesmdash2 Ionophores for poten-tiometric and optical sensorsrdquo Chemical Reviews vol 98 no 4pp 1593ndash1687 1998

[6] E Bakker P Buhlmann and E Pretsch ldquoCarrier-based ion-selective electrodes and bulk optodesmdash1 General characteris-ticsrdquo Chemical Reviews vol 97 no 8 pp 3083ndash3132 1997

[7] M Shamsipur S Sadeghi H Naeimi and H Sharghi ldquoIodideion-selective PVC membrane electrode based on a recentlysynthesized salen-Mn(II) complexrdquo Polish Journal of Chemistryvol 74 no 2 pp 231ndash238 2000

[8] G-J Kim and J-H Shin ldquoApplication of new unsymmetricalchiral Mn(III) Co(IIIII) and Ti(IV) salen complexes in enan-tioselective catalytic reactionsrdquo Catalysis Letters vol 63 no 1-2pp 83ndash90 1999

[9] H Sharghi and H Naeimi ldquoSchiff-base complexes of metal(II)as new catalysts in the high- regioselective conversion ofepoxides to halo alcohols by means of elemental halogenrdquoBulletin of the Chemical Society of Japan vol 72 no 7 pp 1525ndash1531 1999

[10] K J OrsquoConnor S-J Wey and C J Burrows ldquoAlkene aziridina-tion and epoxidation catalyzed by chiralmetal salen complexesrdquoTetrahedron Letters vol 33 no 8 pp 1001ndash1004 1992

[11] C Sasaki K Nakajima M Kojima and J Fujita ldquoPreparationand characterization of optically active quadridentate Schiffbase-titanium(IV) complexes and the catalytic properties ofthese complexes on asymmetric oxidation of methyl phenylsulfide with organic hydroperoxidesrdquo Bulletin of the ChemicalSociety of Japan vol 64 pp 1318ndash1324 1991

[12] Z-L You and H-L Zhu ldquoSyntheses crystal structures andantibacterial activities of four schiff base complexes of copperand zincrdquo Zeitschrift fur Anorganische und Allgemeine Chemievol 630 no 15 pp 2754ndash2760 2004

[13] A Golcu M Tumer H Demirelli and R A WheatleyldquoCd(II) andCu(II) complexes of polydentate Schiff base ligands


synthesis characterization properties and biological activityrdquoInorganica Chimica Acta vol 358 no 6 pp 1785ndash1797 2005

[14] C R Choudhury S K Dey N Mondal S Mitra S OG Mahalli and K M A Malik ldquoSynthesis and structuralcharacterization of [Ni(Me

2NCH

2CH2CH2N=CHC

6H4O)2]rdquo

Journal of Chemical Crystallography vol 31 no 1 pp 57ndash622001

[15] A F Kolodziej ldquoThe chemistry of nickel-containing enzymesrdquoProgress in Inorganic Chemistry vol 41 pp 493ndash597 1994

[16] S Chandra and X Sangeetika ldquoEPR magnetic and spectralstudies of copper(II) and nickel(II) complexes of schiff basemacrocyclic ligand derived from thiosemicarbazide and gly-oxalrdquo Spectrochimica Acta A vol 60 no 1-2 pp 147ndash153 2004

[17] I A Koval M Huisman A F Stassen et al ldquoNew dinu-clear Co(II) and Mn(II) complexes of the phenol-based com-partmental ligand containing formyl and amine functionsstructural spectroscopic and magnetic propertiesrdquo InorganicaChimica Acta vol 357 no 1 pp 294ndash300 2004

[18] G R Newkome J D Sauer J M Roper and D C HagerldquoConstruction of synthetic macrocyclic compounds possessingsubheterocyclic rings specifically pyridine furan and thio-phenerdquo Chemical Reviews vol 77 no 4 pp 513ndash597 1977

[19] D E Fenton ldquoStructural diversity in oligonuclear nickel(II)complexes of unsymmetrical compartmental ligandsrdquo InorganicChemistry Communications vol 5 no 7 pp 537ndash547 2002

[20] NNMurthyMMahroof-Tahir andKDKarlin ldquoDicopper(I)complexes of unsymmetrical binucleating ligands and theirdioxygen reactivitiesrdquo Inorganic Chemistry vol 40 no 4 pp628ndash635 2001

[21] S Torelli C Belle I Gautier-Luneau et al ldquopH-controlledchange of the metal coordination in a dicopper(II) complexof the ligand H-BPMP crystal structures magnetic propertiesand catecholase activityrdquo Inorganic Chemistry vol 39 no 16 pp3526ndash3536 2000

[22] P Gamez J Von Harras O Roubeau W L Driessenand J Reedijk ldquoSynthesis and catalytic activities of cop-per(II) complexes derived from a tridentate pyrazole-con-taining ligand X-ray crystal structure of [Cu

2(120583-dpzhp-

1198741198731198731015840)2][Cu(MeOH)Cl

3]2rdquo Inorganica Chimica Acta vol

324 no 1-2 pp 27ndash34 2001[23] L Sibous E Bentouhami A Maıza G M Bouet and M A

Khan ldquoSynthesis characterization and electrochemical behav-ior of CoII NiII and CdII complexes with N

2O2donor ligands

derived from 441015840-diaminobiphenyl and 2-hydroxybenzalde-hyde or 24-dihydroxybenzaldehyderdquo Journal of Solution Chem-istry vol 39 no 4 pp 511ndash521 2010

[24] N M Shauib A-Z A Elassar and A El-Dissouky ldquoSynthesisand spectroscopic characterization of copper(II) complexeswith the polydentate chelating ligand 441015840-[14-phenylenedi(nitrilo)dipente-2-onerdquo Spectrochimica Acta A vol 63 no 3 pp714ndash722 2006

[25] N M D Brown and D C Nonhebel ldquoNMR spectra of intra-molecularly hydrogen-bonded compoundsmdashII Schiff bases of120573-diketones and o-hydroxycarbonyl compoundsrdquo Tetrahedronvol 24 no 16 pp 5655ndash5664 1968

[26] A A Khandar S A Hosseini-Yazdi and S A Zarei ldquoSynthesischaracterization and X-ray crystal structures of copper(II) andnickel(II) complexes with potentially hexadentate Schiff baseligandsrdquo Inorganica Chimica Acta vol 358 no 11 pp 3211ndash32172005

[27] D P Kessissoglou M L Kirk M S Lah et al ldquoStructuraland magnetic characterization of trinuclear mixed-valence

manganese acetatesrdquo Inorganic Chemistry vol 31 no 26 pp5424ndash5432 1992

[28] S S Kandil G Y Ali and A El-Dissouky ldquoCobalt(II III)and copper(II) complexes of 3-(2-furylidene) hydrazino-56-di-phenyl-124-triazinerdquo TransitionMetal Chemistry vol 27 no 4pp 398ndash406 2002

[29] L C Nathan and C A Traina ldquoTautomerism in complexeswith neutral tetradentate Schiff base ligands the X-ray struc-tures of cadmium(II) nitrate complexes of bis(acetylacetone)-m-phenylenediimine and bis(acetylacetone)-p-phenylenediim-inerdquo Polyhedron vol 22 no 24 pp 3213ndash3221 2003

[30] P J Mccarthy and A E Martell ldquoA proton magnetic resonancestudy of 120573-diketone diimine Schiff bases and some of theirdiamagnetic metal chelatesrdquo Inorganic Chemistry vol 6 no 4pp 781ndash787 1967

[31] S Lechat M A Khan G Bouet and F Vierling ldquoSpectropho-tometric study of cobalt(II) chloride complexes in ethanol andpropan-2-olrdquo Inorganica Chimica Acta vol 211 no 1 pp 33ndash361993

[32] P Gili M G Martın Reyes P Martın Zarza M F CGuedes Da Silva Y-Y Tong and A J L Pombeiro ldquoCom-plexes of Mn(II) and Mn(III) with the Schiff base N-[2-(3-ethylindole)]pyridoxaldimine Electrochemical study of theseand related Ni(II) and Cu(II) complexesrdquo Inorganica ChimicaActa vol 255 no 2 pp 279ndash288 1997

[33] A Vogt S Wołowiec R L Prasad A Gupta and JSkarzewski ldquoSynthesis and characterization of nickel(II) cop-per(II) manganese(III) and iron(III) complexes with new chi-ral salen-type ligand 1198731198731015840-bis(35-di-tert-butylsalicylidene)-(1R3S)-13-diamine-122- trimethylcyclopentanerdquo Polyhedronvol 17 no 8 pp 1231ndash1240 1998

[34] A M A Hassaan and M A Khalifa ldquoMetal chelates ofsome transition and non-transition metal ions with Schiff basederived from isatin with o-phenylenediaminerdquoMonatshefte furChemie vol 124 no 8-9 pp 803ndash808 1993

[35] M A Ali A HMirza and R J Butcher ldquoSynthesis and charac-terization of copper(II) complexes of the methylpyruvate Schiffbase of S-methyldithiocarbazate (Hmpsme) and the X-crystalstructures of Hmpsme and [Cu(mpsme)Cl]rdquo Polyhedron vol20 no 9-10 pp 1037ndash1043 2001

[36] R C Felicio G A Da Silva L F Ceridorio and E R DockalldquoTetradentate schiff base copper(II) complexesrdquo Synthesis andReactivity in Inorganic andMetal-Organic Chemistry vol 29 no2 pp 171ndash192 1999

[37] S ChattopadhyayM S Ray S Chaudhuri et al ldquoNickel(II) andcopper(II) complexes of tetradentate unsymmetrical Schiff baseligands first evidence of positional isomerism in such systemrdquoInorganica Chimica Acta vol 359 no 5 pp 1367ndash1375 2006

[38] R Atkins G Brewer E Kokot G M Mockler and E SinnldquoCopper(II) and nickel(II) complexes of unsymmetrical tet-radentate Schiff base ligandsrdquo Inorganic Chemistry vol 24 no2 pp 127ndash134 1985

[39] A L Nivorozhkin H Toftlund P L Joslashrgensen and L ENivorozhkin ldquoStructural variations in nickel(II) and copper(II)MN4 Schiff-base complexes with deprotonated tetraden-tate 1198731198731015840-bis(5-aminopyrazol-4-ylmethylene)polymethylene-diamine ligandsrdquo Journal of the Chemical Society Dalton Trans-actions no 7 pp 1215ndash1221 1996

[40] A Ghames T Douadi D Haffar et al ldquoStructural and electro-chemical studies of Co(II) Ni(II) Cu(II) and Cd(II) complexeswith a new symmetrical N

2O2Schiff base crystal structure


of the ligand 12-di[4-(2-imino 4-oxo pentane)phenyl]ethanerdquoPolyhedron vol 25 no 16 pp 3201ndash3208 2006

[41] A A Isse A Gennaro and E Vianello ldquoElectrochemicalreduction of Schiff base ligands H

2salen and H

2salophenrdquo

Electrochimica Acta vol 42 no 13-14 pp 2065ndash2071 1997[42] D Haffar T Douadi S Chafaa M A Khan and G Bouet

ldquoSynthesis characterisation and electrochemical study of 441015840-bis(salicylideneimino) diphenylethane and its complexes withcobalt(II) copper(II) and cadmium(II)rdquo Transition MetalChemistry vol 29 no 3 pp 245ndash250 2004

[43] I Kaabi T Douadi D Haffar et al ldquoCrystal structure of a newpentadentate symmetrical Di[4-(phenylimino) pentan-2-one]ether Structural and electrochemical studies of its CoII NiIICuII and CdII complexesrdquo Transition Metal Chemistry vol 32no 5 pp 666ndash673 2007

[44] E K Beloglazkina A G Majouga R B Romashkina A AMoiseeva andNV Zyk ldquoThepreparation crystal structure andelectrochemistry of (5Z51015840Z)-221015840-(alkane-120572120596-diylsulfanyld-iyl)bis(5-(3-pyridylmethylene)-35-dihydro-4H-imidazol-4-ones) and their complexes with cobalt(II) chloriderdquo Polyhedronvol 26 no 4 pp 797ndash802 2007

[45] F Azevedo C Freire and B De Castro ldquoReductive electro-chemical study of Ni(II) complexes with N

2O2schiff base

complexes and spectroscopic characterisation of the reducedspecies Reactivity towards COrdquo Polyhedron vol 21 no 17 pp1695ndash1705 2002

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


O O

NNCH3

EtOH

O O

CH3

CH3

H3C

H3C

H3C

NH2H2N

H2L

24 h60∘C

+

Figure 1 Synthetic route of the Schiff base ligand H2L

2 Experimental

21 Materials and Methods All materials and solvents wereanalytical reagent grade The compounds 441015840-diaminobi-phenyl and 24-pentanedione were commercial samples fromAldrich and purified by standard procedures Their puritywas determined by thin layer chromatography (TLC) ordry column ldquoflashrdquo chromatography (DCFC) (SiO

2 Merck-

Kieselgel 60H) All metals were hydrated chlorides and usedas received Reactions of 441015840-diaminobiphenyl with 24-pentanedione were carried out using ethyl alcohol-reactantsin sealed Rotaflo-tapped Pyrex ampoules (50 cm3) Crudereaction productmixture was examined by TLC and individ-ual components were separated by filtration Further purifi-cation where necessary was achieved by TLC or repeatedDCFC

22 Measurements Products were examined by IR andrecorded with a Perkin-Elmer 1000 series FT-IR spectropho-tometer using KBr disks UV-vis spectra were obtainedin DMF with a UNICAM UV-300 spectrophotometer 1HNMR spectra of the ligand and the diamagnetic complexeswere recorded on a Jeol GSX WB spectrometer instrumentoperating at 270MHz and the chemical shifts to low fieldof the reference are designated positive and given in ppmusing tetramethylsilane (TMS) as external reference NMRsamples were run as solutions in DMSO-D

6 Mass spectra

were recorded on a Bruker Daltonics Data Analysis 31spectrometer using electron impact (EI) conditions Elemen-tal analysis was carried out with an EL III-ELEMENTARMelting points were determined with a Kofler bench andare uncorrected Differential scanning calorimetry (DSC)diagramswere recorded in the 25ndash400∘C range with aMettlerDSC 822e unit with the help of Mettler Toledo STARe SW810 System software the heating rate was 10∘C per minuteall measurements were made in 40mm3 closed Al crucibles

Electrochemical measurements were recorded on aRadiometer VOLTALAB 32 (DEA 332 type) the workingelectrode was a 2mm diameter Pt rotating disk and theauxiliary electrode a Pt wire A saturated calomel electrode

was used as the reference electrode and measurementswere carried out at room temperature DMF was used assolvent and the ionic strength maintained at 01mol Lminus1 withBu4NClO

4(TBAP) as supporting electrolyte The concentra-

tions of species were in the 2510minus3 to 510minus3mol Lminus1 rangeThe sweep speed was 100mV sminus1 unless otherwise indicated

23 Preparation of the Ligand 441015840-(Biphenyl-441015840-diyldinitri-lo)dipentan-2-one TheSchiff base ligand (shown in Figure 1)has already been synthesized [24] In our work howeverthe same product is prepared using a different procedurecompared to either the previous one or that of literature[25] which reported theNMR characterization of120573-diketoneSchiff bases in CDCl

3 Here 441015840-Diaminobiphenyl and 24-

pentanedione were mixed in absolute ethanol and sealedin vacuo in a dry Rotaflo-tapped Pyrex tube (ca 50 cm3)as follows to a solution of 441015840-diaminobiphenyl (075 g081mol Lminus1) was added a solution of 24-pentanedione(082 g 163mol Lminus1) in a 1 2 molar ratio The mixture washeated in vacuo at 60∘C during 24 h to give yellow solutionand pale yellowprecipitateThe volatilematerial was removedin vacuo by condensation into a trap cooled to minus196∘C andidentified as ethanol by IR spectroscopy The residue (117 g)which remained in the tube was washed out using freshethanol and then extracted with the same solvent (3 times 10mL)to give after removal of the solvent from the filtrate underreduced pressure the ligand H

2L that is formed from the

[1+2] condensationThis product was furthermore subjectedto dry column ldquoflashrdquo chromatography (DCFC) using ethanolas eluent and its yield was almost quantitative (83)

24 Preparation of the Co(II) and Ni(II) Complexes All thecomplexes were prepared using the same synthetic pathwaydescribed in literature [26 27] by mixing in absolute EtOHamounts of ligand H

2L (02 g 01mol Lminus1) and hydrated

cobalt and nickel chlorides in 1 1 or 1 2 molar ratio Afterstanding under reflux conditions for 16 h the mixture waskept overnight at room temperature The complex whichprecipitated was removed by filtration washed several times




H2L Yellow 83 134 3482 7568 (7583) 714 (694) 775 (804)([Co(H2L)]

4+)2 Blue 65 gt260 8147 6478 (6486) 621 (593) 699 (687)([Ni(H2L)]

4+)2 Yellow 79 gt260 8142 6464 (6490) 616 (594) 704 (688)[(CoCl2)2(H2L)]

4+ Green 60 gt260 6081 4372 (4345) 425 (397) 475 (460)[(NiCl2)2(H2L)]



(H2L)]4+ and ([Ni(H2L)]



H2L3482 M+ 783053 (C20H21N2O)

+ 202482 (C17H16N2)

+ 10

([Co(H2L)]4+)2

8147 M+ 106864 (C37H34N3O3Co2)

7+ 273922 (C21H21N2O2Co)

5+ 912411 (C9H14N2O2Co)

5+ 17

[(CoCl2)2(H2L)]4+

6081 M+ 105017 (C22H24N2O2Co2Cl)

5+ 183801 (C17H16NOCoCl2)

3+ 632331 (C11H12NOCo)3+ 84

([Ni(H2L)]4+)2

8142 M+ 135993 (C36H34N3O2Ni)

5+ 163931 (C21H22N2O2Ni)

5+ 933161 (C15H17N2O2Ni)

5+ 15













2L)]4+)

2]+ ([(CoCl

2)2(H2L)]4+)+ and

[([Ni(H2L)]4+)



2)2(H2L)]4+ and








(a) (b)

(c) (d)


2L)]4+)

2(b) [(CoCl

2)2(H2L)]4+ (c) and ([Ni(H

2L)]4+)

2(d)














NNO O

NN

O

OHHOII

Enolimine

IKetoimine

KetoamineIII

NHHN O

CH3

CH3

CH3

CH3

CH3

CH3

H3C

H3C

H3C

H3C

H3C

H3C




2)2(H2L)]4+ ([Co(H

2L)]4+)

2and

([Ni(H2L)]4+)



2)2L]2+sdot2H




2)2L]2+sdot2H

2Opre-





2L)]4+)








2L




2OThe spectrum










(ppm)

DMSO

14 12 10 8 6 4 2

(a)

(ppm)12 10 8 6 4 2 0

(b)

(ppm)12 10 8 6 4 2 0

(c)


2L)]4+)

2(b) and [(NiCl





2O complex in


2L in its eno-



2L and the








2L



ONHHN

O

NHHNOO

MM

ONHHN

OCoCo

Cl Cl ClCl

NNO O

Cl ClNi

Cl ClNi

H3C

H3C

H3C

H3C

H3CH3C

H3C

CH3

CH3

CH3

CH3

CH3

H3CCH3

CH3

CH3

middot2H2O

M = Co or Ni

+

+

+

+

+

+

+

+

+

++

+

+ +


ONHHN

O

NHHNOO

MM

ONHHN

O

ClCl ClCl

MM

H3C

H3C

H3C

H3C

H3C

H3C

CH3

CH3

CH3

CH3

CH3

CH3


+

+

+

+

+

+

+

+

++

+ +









[41]



2L)]4+)

2and [(CoCl

2)2(H2L)]4+ respec-




000

002

004

006

008

1 205 150

minus004

minus002


i(m

Amiddotcm

minus2)

E (V versus SCE)

(a)

002

004

006

008

010

012

15 20 05 1minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(b)

002

004

006

008

10 21505

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(c)

002

004

006

008

0 1 15 205minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(d)

050 1 215

002

004

006

008

minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(e)


4 119894 in mA V =


2L)]4+)

2(b) [(CoCl

2)2(H2L)]4+ (c) ([Ni(H

2L)]4+)

2(d) and [(NiCl





11986412

b


4+)2 minus010 +062 +105 +112 minus114 +068 +125 037 1235([Ni(H2L)]


4+minus010 +059 +092 +131 minus117 +068 +117 024 1040


aΔ119864p = 119864pc minus 119864pa

b11986412= 05Δ119864p + 119864pa



4 Conclusion




Acknowledgment


References

















2NCH

2CH2CH2N=CHC

6H4O)2]rdquo










2(120583-dpzhp-

1198741198731198731015840)2][Cu(MeOH)Cl




2O2donor ligands
























2salen and H

2salophenrdquo






2O2schiff base











Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




H2L Yellow 83 134 3482 7568 (7583) 714 (694) 775 (804)([Co(H2L)]

4+)2 Blue 65 gt260 8147 6478 (6486) 621 (593) 699 (687)([Ni(H2L)]

4+)2 Yellow 79 gt260 8142 6464 (6490) 616 (594) 704 (688)[(CoCl2)2(H2L)]

4+ Green 60 gt260 6081 4372 (4345) 425 (397) 475 (460)[(NiCl2)2(H2L)]



(H2L)]4+ and ([Ni(H2L)]



H2L3482 M+ 783053 (C20H21N2O)

+ 202482 (C17H16N2)

+ 10

([Co(H2L)]4+)2

8147 M+ 106864 (C37H34N3O3Co2)

7+ 273922 (C21H21N2O2Co)

5+ 912411 (C9H14N2O2Co)

5+ 17

[(CoCl2)2(H2L)]4+

6081 M+ 105017 (C22H24N2O2Co2Cl)

5+ 183801 (C17H16NOCoCl2)

3+ 632331 (C11H12NOCo)3+ 84

([Ni(H2L)]4+)2

8142 M+ 135993 (C36H34N3O2Ni)

5+ 163931 (C21H22N2O2Ni)

5+ 933161 (C15H17N2O2Ni)

5+ 15













2L)]4+)

2]+ ([(CoCl

2)2(H2L)]4+)+ and

[([Ni(H2L)]4+)



2)2(H2L)]4+ and








(a) (b)

(c) (d)


2L)]4+)

2(b) [(CoCl

2)2(H2L)]4+ (c) and ([Ni(H

2L)]4+)

2(d)














NNO O

NN

O

OHHOII

Enolimine

IKetoimine

KetoamineIII

NHHN O

CH3

CH3

CH3

CH3

CH3

CH3

H3C

H3C

H3C

H3C

H3C

H3C




2)2(H2L)]4+ ([Co(H

2L)]4+)

2and

([Ni(H2L)]4+)



2)2L]2+sdot2H




2)2L]2+sdot2H

2Opre-





2L)]4+)








2L




2OThe spectrum










(ppm)

DMSO

14 12 10 8 6 4 2

(a)

(ppm)12 10 8 6 4 2 0

(b)

(ppm)12 10 8 6 4 2 0

(c)


2L)]4+)

2(b) and [(NiCl





2O complex in


2L in its eno-



2L and the








2L



ONHHN

O

NHHNOO

MM

ONHHN

OCoCo

Cl Cl ClCl

NNO O

Cl ClNi

Cl ClNi

H3C

H3C

H3C

H3C

H3CH3C

H3C

CH3

CH3

CH3

CH3

CH3

H3CCH3

CH3

CH3

middot2H2O

M = Co or Ni

+

+

+

+

+

+

+

+

+

++

+

+ +


ONHHN

O

NHHNOO

MM

ONHHN

O

ClCl ClCl

MM

H3C

H3C

H3C

H3C

H3C

H3C

CH3

CH3

CH3

CH3

CH3

CH3


+

+

+

+

+

+

+

+

++

+ +









[41]



2L)]4+)

2and [(CoCl

2)2(H2L)]4+ respec-




000

002

004

006

008

1 205 150

minus004

minus002


i(m

Amiddotcm

minus2)

E (V versus SCE)

(a)

002

004

006

008

010

012

15 20 05 1minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(b)

002

004

006

008

10 21505

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(c)

002

004

006

008

0 1 15 205minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(d)

050 1 215

002

004

006

008

minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(e)


4 119894 in mA V =


2L)]4+)

2(b) [(CoCl

2)2(H2L)]4+ (c) ([Ni(H

2L)]4+)

2(d) and [(NiCl





11986412

b


4+)2 minus010 +062 +105 +112 minus114 +068 +125 037 1235([Ni(H2L)]


4+minus010 +059 +092 +131 minus117 +068 +117 024 1040


aΔ119864p = 119864pc minus 119864pa

b11986412= 05Δ119864p + 119864pa



4 Conclusion




Acknowledgment


References

















2NCH

2CH2CH2N=CHC

6H4O)2]rdquo










2(120583-dpzhp-

1198741198731198731015840)2][Cu(MeOH)Cl




2O2donor ligands
























2salen and H

2salophenrdquo






2O2schiff base











Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


(a) (b)

(c) (d)


2L)]4+)

2(b) [(CoCl

2)2(H2L)]4+ (c) and ([Ni(H

2L)]4+)

2(d)














NNO O

NN

O

OHHOII

Enolimine

IKetoimine

KetoamineIII

NHHN O

CH3

CH3

CH3

CH3

CH3

CH3

H3C

H3C

H3C

H3C

H3C

H3C




2)2(H2L)]4+ ([Co(H

2L)]4+)

2and

([Ni(H2L)]4+)



2)2L]2+sdot2H




2)2L]2+sdot2H

2Opre-





2L)]4+)








2L




2OThe spectrum










(ppm)

DMSO

14 12 10 8 6 4 2

(a)

(ppm)12 10 8 6 4 2 0

(b)

(ppm)12 10 8 6 4 2 0

(c)


2L)]4+)

2(b) and [(NiCl





2O complex in


2L in its eno-



2L and the








2L



ONHHN

O

NHHNOO

MM

ONHHN

OCoCo

Cl Cl ClCl

NNO O

Cl ClNi

Cl ClNi

H3C

H3C

H3C

H3C

H3CH3C

H3C

CH3

CH3

CH3

CH3

CH3

H3CCH3

CH3

CH3

middot2H2O

M = Co or Ni

+

+

+

+

+

+

+

+

+

++

+

+ +


ONHHN

O

NHHNOO

MM

ONHHN

O

ClCl ClCl

MM

H3C

H3C

H3C

H3C

H3C

H3C

CH3

CH3

CH3

CH3

CH3

CH3


+

+

+

+

+

+

+

+

++

+ +









[41]



2L)]4+)

2and [(CoCl

2)2(H2L)]4+ respec-




000

002

004

006

008

1 205 150

minus004

minus002


i(m

Amiddotcm

minus2)

E (V versus SCE)

(a)

002

004

006

008

010

012

15 20 05 1minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(b)

002

004

006

008

10 21505

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(c)

002

004

006

008

0 1 15 205minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(d)

050 1 215

002

004

006

008

minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(e)


4 119894 in mA V =


2L)]4+)

2(b) [(CoCl

2)2(H2L)]4+ (c) ([Ni(H

2L)]4+)

2(d) and [(NiCl





11986412

b


4+)2 minus010 +062 +105 +112 minus114 +068 +125 037 1235([Ni(H2L)]


4+minus010 +059 +092 +131 minus117 +068 +117 024 1040


aΔ119864p = 119864pc minus 119864pa

b11986412= 05Δ119864p + 119864pa



4 Conclusion




Acknowledgment


References

















2NCH

2CH2CH2N=CHC

6H4O)2]rdquo










2(120583-dpzhp-

1198741198731198731015840)2][Cu(MeOH)Cl




2O2donor ligands
























2salen and H

2salophenrdquo






2O2schiff base











Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


NNO O

NN

O

OHHOII

Enolimine

IKetoimine

KetoamineIII

NHHN O

CH3

CH3

CH3

CH3

CH3

CH3

H3C

H3C

H3C

H3C

H3C

H3C




2)2(H2L)]4+ ([Co(H

2L)]4+)

2and

([Ni(H2L)]4+)



2)2L]2+sdot2H




2)2L]2+sdot2H

2Opre-





2L)]4+)








2L




2OThe spectrum










(ppm)

DMSO

14 12 10 8 6 4 2

(a)

(ppm)12 10 8 6 4 2 0

(b)

(ppm)12 10 8 6 4 2 0

(c)


2L)]4+)

2(b) and [(NiCl





2O complex in


2L in its eno-



2L and the








2L



ONHHN

O

NHHNOO

MM

ONHHN

OCoCo

Cl Cl ClCl

NNO O

Cl ClNi

Cl ClNi

H3C

H3C

H3C

H3C

H3CH3C

H3C

CH3

CH3

CH3

CH3

CH3

H3CCH3

CH3

CH3

middot2H2O

M = Co or Ni

+

+

+

+

+

+

+

+

+

++

+

+ +


ONHHN

O

NHHNOO

MM

ONHHN

O

ClCl ClCl

MM

H3C

H3C

H3C

H3C

H3C

H3C

CH3

CH3

CH3

CH3

CH3

CH3


+

+

+

+

+

+

+

+

++

+ +









[41]



2L)]4+)

2and [(CoCl

2)2(H2L)]4+ respec-




000

002

004

006

008

1 205 150

minus004

minus002


i(m

Amiddotcm

minus2)

E (V versus SCE)

(a)

002

004

006

008

010

012

15 20 05 1minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(b)

002

004

006

008

10 21505

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(c)

002

004

006

008

0 1 15 205minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(d)

050 1 215

002

004

006

008

minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(e)


4 119894 in mA V =


2L)]4+)

2(b) [(CoCl

2)2(H2L)]4+ (c) ([Ni(H

2L)]4+)

2(d) and [(NiCl





11986412

b


4+)2 minus010 +062 +105 +112 minus114 +068 +125 037 1235([Ni(H2L)]


4+minus010 +059 +092 +131 minus117 +068 +117 024 1040


aΔ119864p = 119864pc minus 119864pa

b11986412= 05Δ119864p + 119864pa



4 Conclusion




Acknowledgment


References

















2NCH

2CH2CH2N=CHC

6H4O)2]rdquo










2(120583-dpzhp-

1198741198731198731015840)2][Cu(MeOH)Cl




2O2donor ligands
























2salen and H

2salophenrdquo






2O2schiff base











Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


(ppm)

DMSO

14 12 10 8 6 4 2

(a)

(ppm)12 10 8 6 4 2 0

(b)

(ppm)12 10 8 6 4 2 0

(c)


2L)]4+)

2(b) and [(NiCl





2O complex in


2L in its eno-



2L and the








2L



ONHHN

O

NHHNOO

MM

ONHHN

OCoCo

Cl Cl ClCl

NNO O

Cl ClNi

Cl ClNi

H3C

H3C

H3C

H3C

H3CH3C

H3C

CH3

CH3

CH3

CH3

CH3

H3CCH3

CH3

CH3

middot2H2O

M = Co or Ni

+

+

+

+

+

+

+

+

+

++

+

+ +


ONHHN

O

NHHNOO

MM

ONHHN

O

ClCl ClCl

MM

H3C

H3C

H3C

H3C

H3C

H3C

CH3

CH3

CH3

CH3

CH3

CH3


+

+

+

+

+

+

+

+

++

+ +









[41]



2L)]4+)

2and [(CoCl

2)2(H2L)]4+ respec-




000

002

004

006

008

1 205 150

minus004

minus002


i(m

Amiddotcm

minus2)

E (V versus SCE)

(a)

002

004

006

008

010

012

15 20 05 1minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(b)

002

004

006

008

10 21505

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(c)

002

004

006

008

0 1 15 205minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(d)

050 1 215

002

004

006

008

minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(e)


4 119894 in mA V =


2L)]4+)

2(b) [(CoCl

2)2(H2L)]4+ (c) ([Ni(H

2L)]4+)

2(d) and [(NiCl





11986412

b


4+)2 minus010 +062 +105 +112 minus114 +068 +125 037 1235([Ni(H2L)]


4+minus010 +059 +092 +131 minus117 +068 +117 024 1040


aΔ119864p = 119864pc minus 119864pa

b11986412= 05Δ119864p + 119864pa



4 Conclusion




Acknowledgment


References

















2NCH

2CH2CH2N=CHC

6H4O)2]rdquo










2(120583-dpzhp-

1198741198731198731015840)2][Cu(MeOH)Cl




2O2donor ligands
























2salen and H

2salophenrdquo






2O2schiff base











Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


ONHHN

O

NHHNOO

MM

ONHHN

OCoCo

Cl Cl ClCl

NNO O

Cl ClNi

Cl ClNi

H3C

H3C

H3C

H3C

H3CH3C

H3C

CH3

CH3

CH3

CH3

CH3

H3CCH3

CH3

CH3

middot2H2O

M = Co or Ni

+

+

+

+

+

+

+

+

+

++

+

+ +


ONHHN

O

NHHNOO

MM

ONHHN

O

ClCl ClCl

MM

H3C

H3C

H3C

H3C

H3C

H3C

CH3

CH3

CH3

CH3

CH3

CH3


+

+

+

+

+

+

+

+

++

+ +









[41]



2L)]4+)

2and [(CoCl

2)2(H2L)]4+ respec-




000

002

004

006

008

1 205 150

minus004

minus002


i(m

Amiddotcm

minus2)

E (V versus SCE)

(a)

002

004

006

008

010

012

15 20 05 1minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(b)

002

004

006

008

10 21505

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(c)

002

004

006

008

0 1 15 205minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(d)

050 1 215

002

004

006

008

minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(e)


4 119894 in mA V =


2L)]4+)

2(b) [(CoCl

2)2(H2L)]4+ (c) ([Ni(H

2L)]4+)

2(d) and [(NiCl





11986412

b


4+)2 minus010 +062 +105 +112 minus114 +068 +125 037 1235([Ni(H2L)]


4+minus010 +059 +092 +131 minus117 +068 +117 024 1040


aΔ119864p = 119864pc minus 119864pa

b11986412= 05Δ119864p + 119864pa



4 Conclusion




Acknowledgment


References

















2NCH

2CH2CH2N=CHC

6H4O)2]rdquo










2(120583-dpzhp-

1198741198731198731015840)2][Cu(MeOH)Cl




2O2donor ligands
























2salen and H

2salophenrdquo






2O2schiff base











Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


000

002

004

006

008

1 205 150

minus004

minus002


i(m

Amiddotcm

minus2)

E (V versus SCE)

(a)

002

004

006

008

010

012

15 20 05 1minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(b)

002

004

006

008

10 21505

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(c)

002

004

006

008

0 1 15 205minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(d)

050 1 215

002

004

006

008

minus004

minus002


i(m

Amiddotcm

minus2)

000

E (V versus SCE)

(e)


4 119894 in mA V =


2L)]4+)

2(b) [(CoCl

2)2(H2L)]4+ (c) ([Ni(H

2L)]4+)

2(d) and [(NiCl





11986412

b


4+)2 minus010 +062 +105 +112 minus114 +068 +125 037 1235([Ni(H2L)]


4+minus010 +059 +092 +131 minus117 +068 +117 024 1040


aΔ119864p = 119864pc minus 119864pa

b11986412= 05Δ119864p + 119864pa



4 Conclusion




Acknowledgment


References

















2NCH

2CH2CH2N=CHC

6H4O)2]rdquo










2(120583-dpzhp-

1198741198731198731015840)2][Cu(MeOH)Cl




2O2donor ligands
























2salen and H

2salophenrdquo






2O2schiff base











Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




11986412

b


4+)2 minus010 +062 +105 +112 minus114 +068 +125 037 1235([Ni(H2L)]


4+minus010 +059 +092 +131 minus117 +068 +117 024 1040


aΔ119864p = 119864pc minus 119864pa

b11986412= 05Δ119864p + 119864pa



4 Conclusion




Acknowledgment


References

















2NCH

2CH2CH2N=CHC

6H4O)2]rdquo










2(120583-dpzhp-

1198741198731198731015840)2][Cu(MeOH)Cl




2O2donor ligands
























2salen and H

2salophenrdquo






2O2schiff base











Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




2NCH

2CH2CH2N=CHC

6H4O)2]rdquo










2(120583-dpzhp-

1198741198731198731015840)2][Cu(MeOH)Cl




2O2donor ligands
























2salen and H

2salophenrdquo






2O2schiff base











Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




2salen and H

2salophenrdquo






2O2schiff base











Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

cobalt(ii) and nickel(ii) complexes with n 2 o 2...

Documents