Synthesis , reacti ons, spectral anclmagnetic studi es of chloro-{2-(o-hydroxyphenyl)­benzimidazolato }-cobalt (II)

R I< Dubey""'" & eM Mishrah

., Synthctic Inorg;l: l ic Metallo-Organ ic Research Lahoratory J)epartillent o j' Cheillist ry. Un ive rs ity oj' A llahab;lu. A ll ahahau 2 1 I 002. Inuia "J)cp;l rtlncnt o j' Chc llli stry . R J Co l lcge. Ghatkop;ll'. M Ulllhai ·WO 06S. Inuia

Elll;li I: r;ljal kox Y@Y;lhoo.colll

/{cccil 'cd 30 .I({III/IlIT 20()o: /,cI 'iscd 2-+ .lull' 20()o

1\ new anu lww l (chloro) cOlllp lcx oj' cobalt ( II ). l ( p-CI )~Co1 (1l 2-( ph/.)b l. ( 1) whcrc pbz=(2- (o-hyuroxyphcny l ) 1

IKIl/.illliuazole. 11 2 = nUlllher oj' conllcc ti vit y si tcs in vol veu in hounuing the Illctal. has hce n synthes izcu quaillitati vcly hy the intcr;\ction 01' an aqueous ethanolic so lut ioll o j' coh;!It ( ll ) chlor iue with hot et il ano li c so lution 01' (2 -(o-hyuroxyph cny l ) 1 hcnzilll iu;Wlle. (ph/.II ) in equilllo lar ratio. Th is ucr ivati vc is insol uh le in COllllllon organic sol vcnts anu can J'orlll aUUul'l . when treateu with tctrahyuroJ'ur;\:l. Further. cO l11pl ex 1 upon trcating with sodiulll salt s oj' SchilT hascs . N;l(slllah ) anu N;\(S;lp). alkoxo N;\ (OPri) I. ;\ryloxo Na(OA r) ;lllU tetrai sopropo xya luillinate N;i( AI (OPri) }-l in equin1ll1;\r r;ltio in

hcnzcnc/T llle Illeu iu111. prouuces dcrivati vcs o j' the typcs: 1I11 ~ - ( s lllah Jl CO(11 2-(pbz) }1 2. I(sap ) CO(1l 2-( phz) 11 3.

1 ( ~I-O Pri)~Co2 (1l ~ - ( ph /. ) 1 2 1 4. 1 ( ~I-O!\r)2 CO2 (11 2-(phl.)}2 1 5. and 1 ( ~I-OPri)~ (AI (OPrih l Co (1l 2-(phzJl I r. 1\ 11 these CO ll1pl cx cs have hccn ch aracteri zeu by clcl11c nt;!1 ;ll1 ;!I ys is. IR . UV-I' is. F/\!3 -Ill;ISS and l11agnctic stuui cs to cx pillre thc Jlllssihi l it y oj' strul'lllr;!1 eluc iuat ion s.

WC Codc: Inl. Cl s C07F I/OS: C07C2) 1/02

The literaturel .,) survey on th e benzimida 7.o le co mplexes or ':,(( tr~ln s iti o n l1letal s reveal s that these co mpl exes ha ve recei ved sca nty attenti on poss ibl y due to their in so lu bi l ity. po lYl1leri c nature ~lnd non-vo latile c h~lr~ t c t e ri s ti esl-') . There tS no menti on or an y chl oro complexes o r these later ' :,(( tran siti on metal s in vo l v ing benzimidazo le moieti es. T he imidazo le l igand has exce llent medi c inal properties and bio log ica l activit ies(,·H 1t was. therefore. considered worth w hile to sy nthes ize ch loro complexes or Ltter ':, d' tran siti on metal s containin g 2-{ O-( hydroxyphen y l)} be nzimidazole. (pbzH ) . Even thi s co mplex wa s found to be . I bl . . I ') - 11 I I In so u e In common organI c so ve nts • t l erC)Y m:tKing rurther reacti ons almost dirficult. A breaK­th rough in thi s di rection ha s been th e synthes is of hydrocarbon so lubl e mi xed li gand complexes for the first time in our laborat ory by the interacti ons of the above chl oro complexes w ith sodium salt s of Sc hilT ba ses 1c (s mabl-l and sap H ), aIKoxo-. aryloxo­and tetraalK oxyalulllillate li gand s. However. some nove l chloro-bimetalli c compl exes o f later '3d' tr;ln siti on metal s containing aIKoxo-, aryl oxo -. acet y lace ton:t to- Illo iet ies ha ve a I read y been

11'- 1-1 K . I . . I I ' report ee - . eeplng t lat In Vtew, t l e sy nt l eSts.

reacti ons and characteri zation (fR. UV-v is. FAI3-ma ss and magneti c studi es) or new and nove l hydrocarbon so lu ble mi xed li gand compl exes or 2-{o-(hydroxyphenyl) )-benzimida zo le w ith cobalt ( II ) arc reported here.

Materials and Methods All chemica ls used throughoul the course or

experimental work were o f G.R. or Ana lar grade. Spec tl'Oscopic grade so lvents were employed ror recording the spec tra. Benzene (BDH ). iso-prop;tno l (B DH ) and telrahydrofu ran (L oba) we re dried according to standard lilerature procedu re. Aluminiulll isopropox idel5 was prepared by di sso lving aluminium roil in isopropanol in thc presence or H gCl as catal ys t and reflux ing it for - c) h. Final product was purified by distillati on. (b.p!. 9S DC). Anal ys is o f compounds for the quantitati ve determinati on of cobalt was carried out by atomic absorption spectroscopy. GBC-932 AA. Aluminiulll content present ill the bimetallic complex \Vas determined after precip itating aluminium as it s ox inatel('. Chloride content was es timated by Vo lhard 's melhod lG Isopropoxide content in the corresponding isopropoxy deri vati ve was es timatcd

II DI /\ N .I CII EM. SEC !\. OCTOI3ER 2006

by an oxi dimetri c meth ods ' 7 JR spec tra (4000-200 Clll-I) were recorded ;IS nujo l mull s using Perkin Ellller 1000 FTI R spec trophotometer. Elec tron ic spectra o f the cOlllpound s were recmd ed in benzene ;Ind/or tetrah ydrofuran on a Hitachi-220 spectrophotometer. Magnetic susceptib ility measurements were made at room temperature (n.s°C) by GOlly method.

Synthesis of ligands {2 -(IJ -ilytiroxYJlilelly l)}-bell ; illl itia;IJ le (Jlb;ll)

The li gand !2-(0-hydroxypheny l)} ben zimidazo le was synthes ized according to prev iously es tabli shed literature mcthods IX.

SlIlicylitiwc-2-lIIelily l-l-alllilllJ bell~etle (.1'11111/;11)

The ligand srnabH "J was preparcd by rc riuxing ( for -6 h) equimolar aillounts of toluidine ( 10.7 g. I()O Illlllol) and salicy laldehyde ( 12.2 1 g, 100 mmol) in methanol (-30 cm\ Further, sodium salt of sali cy l idenc-2-methy l-l-amino bcnzcne. Na(smab)') \Vas prcpared by di sso l ving cqu imolar amounts o f sodium mctal s and salicylidcne-2-methy l- I­aillinobenzene in methano l.

Sal icy l idcne-2-a mi nopyridcnc(sap l-I )211 and it s sodillm salt s. Na(sap) wcre prepared by the identical Illethod s as given above.

2-/1 III ill ()sIJtiilllllpil ell IJlale I Na(O-Cr.11 IN 112) I 2-Aminosodillmphellolate was prepa red by

rcClu xing (fm - 12 h) eq uimolar amoullt of 2-amillophcnol and sodium metal in THF.

SIJtiil lllllelralllklJxyallllllillllle INa{III(Ol'ri)J) }

Sodium tetraalkoxyaluminate \Vas prepared by . , I

standard l itera ture procedure- .

I'repllralilJlI (!/ cilIIJro{2-(IJ-ilytiroxYJiilellyl)} /; (! II ~ illlitill7. lJ lallJ­

co/;all(II); {(j-l-C1hCIJ2{r{ (JI/; ;)hl I cOllllilex

A frcsh I y prepared aqueous ethanol ic so lution (50''*, ethan ol. -SO cm' ) o f cobalt ( II ) ch loride (3 .38 g. 14.2 mmol) was added dropw ise to a pre-s tirred hot ethanol (-75 cn1") so lution conta liling 2-(0 -hydroxyphen yl)bellzimidazo le (3 g, 14.2 Illlllol ). whi ch produced a pinki sh brown coloured precipitate. Fllrther, drop\Vi se additi on 0 dilute sodiulll acetate so lution with stllTlIlg afforded pink coloured

prec ipitated l (p-Cl )cCoc !112-(pbz)h i 1. It wa s then digested (- I h). filtered, washed with aqueous ethanol and dried at -100°C under reduced pressure to give purple pink powdered solid . (4 . J3 g. 95 %). (}{,Found(Ca lc.): Co. I 9.2( 19.3); CI. 11A ( 11.6).

Rcacliolls or 1()l ·C1)zCo!!r((phz)} ! 1 I with !'I.I (s lllah )

To a stirred hot ye llow ish green suspension of chlmo-!2-(hydrox ypheny l) } -henzoxazo lato­complex of coba lt ( ll ) (0. 30 g. 0.98 mll1ol) in tetrahydrofurall (-30 cm'), was added sodium salt o f sa li cy liclene-2-methy l- l -aminobenzene (()'23 g. 0.98 mmol) in eq uilllolar rati o. The reacti on mi xture \Va s all o\Ved to reflux or about I h. all o\Ving colour or the so lu tion ch;lnging frolll ye ll o\V ish greci1 to reel. The prec ipitated NaCI (0.06 g. 0.99 I1lmol) WelS I'emoved by filtrati on. The solvent \Vas removed fm l1l the f il tr;ltc under reduced pressure to afford a reddish brown sol id

prod uct 1!11 C-(s mab) }Co!11C-(pbz)} I 2. which W;IS

purified by recrys talli sati on from ;i benzenelTHF mi xt ure to finall y give reddish bro\Vn po\Vdered so lid (OA3 g. 93(}{,). (X, Found (Ca lc. ): Co. 12.5 ( 12.3)

Simi lar procedure \Vas used to isola te 1!11 C-(sap ) }

Co !11C-(pbz) }I 3. 1 ( ~l-OPri ) 2C02 !11 C-(pbz) }cl 4. I(p­

OAr)2Coc {11 C-(pbz) h! 5. and 1 ( ~l-O Pri hCO ! 11 2-(pbz) }cl 6. The synthetic and anal yti ca l detail s of ;111 these comp lexes arc g ive in T;lbl e I .

Results and DisclIssion When a hot ethan oli c sol ution of !2-(o­

hydroxypheny l) } benz imidazo le \Vas added to al1 aqueous ethal1 0lic soluti on or coba lt (I I) chl oride in equimolar rati o. foll owed by the add jti on of dilute so lution of sod ium acetate. bull coloured solid

precipitat e. I ( j1-Cl )2C02 !112-(pbz) 121 was obtained.

The prec ipitate obtained has been digested. foll o\Ved

by filtrati on. washing and dry ing at - 100°C under red uced pressure, prod uced purple po\Vder sol id (Table I ) \V hich is shovvn in Scheme I .

The comp lex has been fou nd to be inso luble in mos t or thc cOlllmon organi c so lvents such as benzene, chloro form. isopropanol. etc. wherea s so lubl e in DMF. DMSO, TI-IF and pyridine. Thi s new complex is colou red so lid and has tendency to form adduc ts \Vhen treated w ith THF.

The chloro-complex . I (p -CI )2Cod 11 2-( pbz) } ci undergoes metatheti c reacti ons wi th sodiulll salt s of Sch ill bases INa(s mab) and Na (saD) I. alkoxo­Na(OPri). ary loxo Na(OAr), I where A I' '= N H cC" H ~ I and tetrai sopropoxyalul11inate Na! AI(OPri)~ } in I: I stoichi ometric ratio in THF represelHed by:

[(CI)Co(pbz)] + Na (X) -----_ I (X) Co (pbz)] + NaCI st irred/ref lux

rwhere x = sll1;i1) 1'01' (2). sap for (3). OPr; for (4) ; ! lld OA r for (5 )1 C6 HJ THF

[(CI)Co(pbz) ] + Na {AI(OPr),}---- _, [{AI(OPr'),}Co(pbz)] + NaCI I stirred/ [),

j\o

2

.3

-I

5

(,

I)U II I: Y & M ISIIR /\ SYNTII ES IS & C I I /\ R/\ CT ER ISi\TI ON OF Co( ll ) COM PLEX 0 1' I3ENZ I M ID /\ZO Ll~ 22()5

T ahle' 1 - Sy nthl' ti c an~dyt i cal ;lI ld Illagneti c oi" the Ill ixed lig~lIllJ cOlllp lcxes orcohalt ( I I )

ReaCI;lIl1S (g . IlllllOI ) Product (g. (1< y ie ld )

CoCI , 6 11 ,0 + ph / ll I (p-C I ),CO,l ll '- ph/. l , 1 (:US . I -I::! ) (\ . I -L~ ) (-U :I. 95 ) I + Na (s lll ;lh) l (s lll ah )Co l ll '-( ph/) 1, 1 (0:10. O<JS ) (on 0<)8 ) (0 -1 :1,9:1 )

I + Na (sap ) I (S ~ l p )eo Ill' -(pbl.) 121 (030.098) (0.-1-1 . 097 ) (0 -1 2, 90 ) I + N ~I ( O Pr') I (p -OPr'),Co, l- (ph/) 121 (0:10. O.I)S) (0 . 1:1. ( 1) 1)) (0::!8 , 9:1 ) 1 + N a(O;\ r) I ( ~l - Oi\r ),Co , l- ( phi.) 1, 1 (030.099 ) (0 13.099) (033. 89 )

I + N;d /\ I(O Pr')4 1 I (~l-O Pr'),l /\ 1(0 1'1" )21-(030.0' )9) (O::!S:I. 0(9) Co l -(pI1l.)12 1

(Q28. (3 )

NH NH2 at 2 +0=6-9 (ii) Distilled at (-) NHJT

' { i )t.( I ~O~; 1 1-10

-2J 8Q C (-)H2'0

H

0:>-9 H--·O

(l'bzH) (pbzll + CoCll .6H.O

(i jAq. EtOH -611 20 + Het Ij (ii ) CH]COONu (i ii) Dried u'nder reduced pressure at 100°C

[(Cl)Co(Pbz)] THF

Phys ica l S t~lt c Mel t in)! point (oC )

Purp le powder _,50

so l id

I3row ni sh hl ;lck 1-1-1- 1-17

crys ta l so l iLl

I3 roll'n powdered 170 so l id

Ye l low ish green :1 05 nyst;d l inc soli d

I3rown so liLi 300

L ight hrown 160 crysta lline solid

+ Na(OR) (R = Pri/Ar)

[Where X ~ CI for ( I), OPr' for (4) and OAr for (5)]

Scheme I

Found (C ~d c d I. (;,

C II N Co

50A ::!.<)O 90 19 10 (57 -1 ) (::!97) (9 ::!5) ( 1<) -1 )

57.0 -1 .20 S.-I I ::!.O (578 ) (-I A ) (S8) ( I ::!:I )

5::! A :150 11 .5 1::! .5 (5 -1 5) (387) ( I ::! 0 ) ( 1267 )

57.-l -1 .50 S -IO I 8 .. ~ (5S7 ) (-I SO) (856) ( 18 0-1 )

60.::! 3 -1 0 5.50 16.0 (6060) (:; 9<) ) (597 ) ( 16m )

56.0 5.50 50 II .S (5() 5) (5 97) (5'27) ( 11 10)

(2)

C'I II 10 ( I 1 7)

2206 INDI ,\ N J CII EM. SEC ,\. OCTOJ3E I~ 200()

These der i v~ lti ves arc co loured sol id, so lu ble in

common organi c so lvent s like C,H(" CCI -l , C I-ICI , etc. ~Ind I1:l ve been puriri ed by recrys tal l izati on in the so luti on or bcnzene-THF mi xture.

II{ ~ Jlcl'lral studi es

Inf'rared spec tra o r l (p -C I)cC02111C-( pbz)fc l showed

. . ..... ' .' -l s tru c tur~t1l y use lul IR ~Ihso rp tl o n band s" - in the

r~lll ge 280-l29 cml

1'01' V('o.o. 2l-i-220 cm·1

1'01' VCO"'\.

alld 16 1-i - I -iR I cm·1

I'm V c= ,'\ .

T he c h ~lra c t e ri s ti c hand s 1'01' benzimi dazo le moiety

prese nt in the complex 1 ( ~l -C I )c C02 1112-(plJl.) H li e in

the r~ l n ge 20()-'.?2S cm·l A strong II{ band observed at

- '.?3 -i cm·1

is the charac teri sti c f'or V('o.:\ frequency . IR ahsorpt ion b~lnd in the ran ge 2-iS-262 cm·

1 is the

character isti cs i'or \I (o.il stretching f'requency, ind icating the l igand to be oxyge n bonded . A n intense

band at - 280 cm·1

IlaS been ass igned 1'01' \1 ('0.('1

hridgi ng vibra ti on, whi ch is the charac teri sti cs o r br idging chl Ol' ine in tetra hedral geometry . IR peak ror C=N "roul) is obse rved at - I () I S cm·

1

in the ;:;-

benzimidazole li gand. wherea s in the present cont ex l. the complex showed the IR rrequencies in the range 16 1-i - 1-i8 1 cm·l

. Shirt to f'requencies o f the metal li gand complex rrolll that of the i'ree li gand revea ls the coord ina ti on through hetero ' N ' at om o r 'C=N' group

in the complex. The IR f'requencies o r the phenoli c - OH group o r

the li gand is generall y observed around l -i6S cm·1

wh ich di sappear Oil complexa ti on indicating that hond i ng is through phenol ic oxygen a tom through ml' t~t1 ion after deprotonati on o f the pheno li c -OH grou p or the li gand. It is rurther supported by upward

shifting o f' \I(C-O) (phenoli c) observed ~I t 1248 cm·l, wh ich gets shifted to 1257 cm·

l. A ll these

ohservati ons sugges t a d istort ed t etrahed r~ tI geollletry through chl or ine br idge around ce ntral metal cohalt ( II ).

Sod iulll salts or sali cy lidelle-2-methy l-l -ami nobenzene a nd sa I icy I i dene-2 -a m i nopyrid i ne exh ibit bands at - 15l() cm l and 1600 cm,l

respec ti ve ly, whi ch arc the characteri sti cs o f C=

group. T he complexes 1 {11C-(smab)Ko {11

2-(pbz)f1

~I n d 1 { 11 2 _(S~ip ) I Co { 112-(pbz) I I ex hi bited the rrequen­

c ies at - 1480 cm·1 and 1540 cm·1 respect ive ly, thereby show ing a lower shirt or frequencies on cUlllpi<.:.':a ti on. Thi s suggests the parti cipati on of 'N' 0 (' C=N gro up or the li gand. T he new bands observed in the complexes in the range 45S±I S cm·1 ha ve been

ass igned 1'01' v " o.;-\ and V('oO, respectively . The shift in

the ba nds obse rved 1'01' mi xed li gand comple x I(p­

OA rb CO2 { ll C-(pbl.) f21 in the range i 285- 127() CIllI

is characteri sti c 1'01' bond formati on between metal and phenoli c oxygenC:i2:i .

The Ill i xed li gand complexes, Ip -OPr')cCo2{ llc-

(pbz) f 21 (ol ) ~Ind 1 ( ~l-O Pri ) 2 {A I(O Pr')2 fCo { llC-(pbz)f 1

ex hi bited characteri sti cs VIC.O) CO in the ran ge 10000±%O cm·1 and 11 50±950 cm·

I, respec ti ve ly . The

absOI'pti on band observed at - 1150 CI11·1

is poss ihl y due to termina l isopropoxy groupslC an d tile bands at IO-iO and 950 CIll·

1 arc charac tcri sti cs 1'01' bridging

isopropoxy groups. In additi on to these, ba nds ~ It 700

CIll· 1 ~Ind 410 cm· 1 ha ve been ass igI1ed 1'01' \I ,\I.() ~ In d \l eo.o. The frequency obser ved ,It 162() em,l has been

ass igned for v('=:\ o r benzimidazo le moiety . In the isopropoxy bridged compl ex, the ba Ild at 460 Clll ·

1 is

attri buted to V( .. " .

UV- yisihk sperlral st udies

T he elec tronic spec trum o r 1 (p -CI)2Co2 { llc-(pb?) f cl

in DM F ex hi bits an absmpt io l1 bandcl

in the j' ~ ln ge 202()O-2325() CIll·1 which may be due to tran siti on

indicating di stort ed octahed r ~ d (D-l il ) geo metry.

In the complexes, 1 {11 C-(s rnab) I Co \ 112-(pbz) f 1 ~ I nd

1 i l1 C-(sap) ICo{ 11

2-(pb7.) f I, the absorpti on ba nds h ~I\ ' e

been observed ~ It -2 1505 c rn· 1 ~I n d at - 2288l Cllli

(24 155 sh) respect i ve ly . It shows that the coord ination o r THF is operati ve and hellce tile ba nds charac teri sti cs I'm oc tahedral geonll:try ha ve on ly been observed, as these spectra have been recorded in benl.ene-TH F mixture.

i\ I agile! ir :.; tudi l'S

For cobalt ( II ) Cd7) high spin complexes, tile

theoreti cal magneti c moment value, pdl arc expec ted to be 3.9 8M: but the actual ex perimental \'~ tlu e

generall y LtI ! in the ran ge o r 44-5.l 13M dlle to orbital contributi ons

cO which Illay v ~Iry w ith

stereochemistry (4.4 to 4.8 13M for tetrahedral : 4 .S to 5.4 8M 1'0 1' tri gonal -b ipy ramiclal and 4.7 to 5.l 13M or oc tahedral ) o f the complexes.

Fm low spin complexes , these va lues generall y lie in the range 1.7 to 2.9 8M (2.2 to 2.9 for t etrahedr~d,

1.7 to 2.0 or tri gonal bipy ra midal and 1.8 to 2.S I'or oc tahedral geometry).

The magneti c moment of the new ly synthes ized cobalt (II ) complexes conta ining henzimidaw le

moieties, 1 ( ~l-Cl )2C02 {11 2 -( pbz) f 2 J at room temperaturc was round to be 3.8 13M w hich is non-agreemcn t w ith the reported range ror high spin

',' ~+

©C>-J») I / >

/"0 /

C. I m/z = 303 (monomer )

0- 1+ ©>

' .. ", .... J'" "' .

' / ", ," "

© <i::© m I l = 607 ({)Imer)

f

miz = 268

II

II I

miz = 494

octahedral or tetrahedral geometry. T hi s 10\Vn value of magneti c moment can be understood on the lXlsis 0 1' polymcric nature of the comp lex and anti fe rromagnetic superexchange phenomenon. \V h ich occ urs bet\Veen the two cobalt ( II ) metal centres . th at might be through chl orine brid ges.

FA II-mass sped ral studil'S

The rAB -mass spectrum of represent ati ve compound of coba lt (l I). I ( ~l-CI hC02 l11 2 - ( p bz) 121. showed an importan t peak at JII/:' = 607. whi ch correspond s to the molecular \Veight o f compound supported for the dilllc ri c structure. The compl ex al so showed fra gmentati on ion peak at III/? 304, indi cating the fragmentati on of dimer molec ule to monomer.J·11I Other important peak s \Vere obse rved atlllh 576.494, 440, 402 , 322, 289. 268. 197 and 177 indicating fragmentati on of li gand from compl exes by the formation of radi ca l ca ti ons. Va ri ous Illass fragment ation pallerns arc sho \V n in Scheme 2. whi ch arc characteri stic of compos iti on and structure of the given comp lex ..

m/z = 177

miz = 440 miz=322

m/z = 402 miz=289 miz = 197

Scheme 2

Acknowledgement Authors arc grate ful to Head. Depa rt ment o r

Chemi stry. Uni ve rsit y of Alla habad ror prov iding laboratory rac iliti es . and CDR!. Lucknow 1'0 1' mi cl'Oan al ys is and FAI3-mass stud ies . lIT Mumb,li is also ack nowledged for spectral and mag netic studies.

RcI'erences I Mcssaccs i M. Pinna R. l3idd an M & Punti n: ll i G. I llo/,X

Cililll I\ C/({. SS ( 19S.I) 1) 1: Ponli cc ll i G. Mess~l ce s i ivl. S ;I~ tl ' \ '

13 /\. l3 ~ il a i ac h 13 S uhr~l ln a n a n & ChL'l'Y. III dill II .I I 'll/'( ' /\1'1,1 I' /r \', 24 ( 1986) 206.

2 Il amillo ll G .I & Kohol E. 1\ lIs l .I O Il' II I. 25 ( 1972) 22.1). .I Dul l E J & Hug hes M N . ./ CI/I'III Soc. 1965(/\) 2 1·U . 4 Du hey R K. Du hey U K & Misltra C M. Fmll s iII" l ('//1'11 1 (in

press). ) Sabatini /\ & l3erti ni I. I ll o /'g CiI(,III . 4 ( I % ) ) 9)9.

6 SCOl l Moore .I . KUliKO V /\. LlchicOllC R G & Mar/i ll i I C. Ill o /'g ( ·/relll . .IS ( 1994) 4 .

7 Tid Well R R. Ones S K. N ai lll ~1I 1 N A. Berge rs L C. Iklkc~

W 13 & Hall J. CiII' II IOI /I I'W/ I.'· . 37 ( 199.1) 17 1.1. S l30ulllan E D & Reed .l . ('oo /'d Cilelll N(,I '. 104 ( 1990) 14.1. 9 Duhey R K. Mish ra /\ N & Mishra C M. /'mc NIII /\md Sci:

I lldia . 75(A ) (2005) 2.1 9. 10 Duhey R K. Mishr;1 C M & Mi shra /\ N. I lldiall.l Chl 'lI l. 44r\

(2005 ) II W

22()8 IN DIAN J CH EM. SLC 1\. OCTOIlER :2006

II Duhey R K. Duhey l J K & Mi ~ hr;1 C 1\1. I lldillll .l C/II'III. 4'i i\ (:2006 ) 16:1 S.

1:2 Duhey R K. Singh ;\ & M l' lirotr;1 R ein I ldl'llll ct's ill

iIIl'lIIl/o -0 rg({ lIic ('/it'lI/i.l liT. edited hy R 13uhra ( R I3 S/\ Puhli sher. J;li pur. Indi;l). 10<)1). pp . 410 ;/iid n:i'crcnces therein.

10, Duhey R K. Tmll s iII l'l ('//1'11/. I S ( 19In ) 24.\ . 14 Duhey R K Singh A & M ehrotr;1 R C. I lldillll .I ('{I I'll I. :1 1 A

( 1<)02 ) 1'i6. 15 \1chl'lltr;1 R C. .I l l1d ioll CI/I'II/ Snc,'\O ( 1950, ) 5S'i. I () Vuge! A I. I I T!'.II Ilnll/.. 1If' (jll ll lllil({lil '(' IlIflrgllllic I l lIo/,'sis

(Longman. London ) I97S. 17 Bradley D C. Ii alilll I: iVI A & \V;ldla w W . .I ('//1'111 SoC,

( 10'i0) 3450. I S W ;i1 tcr J L & Fre ise I' ll. , 11111/ CI/I'III . 24(6) ( I <) 'i:2) 08'i . II) Kher;1 13 . Shanna A K & Kau s hi~ N K. I 'nlrl/l'dmll .:2 ( 108.\)

11 77. 20 T hom;ls R. Thomas K J & 1';lrmes ll'arn;1 G . .I I lldillll ('/i I'll I

Soc. n ( 19%) 'i:2<):2 .

:2 1 rlradley D C. M ehrotr;1 R C & Gaur 0 P. /1/1' /(/1 , I //..'J.\id, '

(Acldemic Pre". Lundon) 1078.

:2:2 Adams 0 M. /l /1'1II1- I-igl/l/lllllld I<1'11I11'i/ \ 'i h l'lllinlls ( r:d\l'ard A rn old. Londun ) 1967.

:2:1 CI;/l1 R J II. IIlIlng l' lI ('/inlli.l·liT ( /\ c;tliLIn il' Pres.s . . " l'lI YOI'~ ) I%S.

:24 FCI'r: /I'o J R. 1.011' Frl'(I"I'II CI' \fiIJIWinll .1 of' Illorglllli l' 1II/(1 ('()()f'(lill(f/ioll ( ·OIlII )() III1r/., (1)l enum. Nell' YOl'~) I In I

:25 Nakamoto K. Ill /i'lllnl SIN'c /m II Ill o rg llllic ({lid ('(Jori/illll/i ll ll ('1111 IIWII II d . .+ '11 r:dn (Wil cy- int l'l'scienn:. :'-!CII YO lt ) 108(>.

:26 l3 i r;ld;lr N S. l'uj;lr M i\ & Mar;lthe \' R. I lldill ll.l C/iI'II /. I(M ( 107 1) 7 1:2: Chaki'awani P 13 & Kh ;lnna 1' . .I I I/(lillll ('/11 '111

Sri<' . 6 1 ( 1084 ) I 1:2 : Oklr M L GUpt;1 V K 6: Singh O. Illdillll .I ('/inn. }7 (A ) ( I08S) n0.

:2 7 Lewl 1\ 13 1'. Ino rgllnic U I'('/wnic "'IJ, 'CI '·,).'·col'r . 2".1 I:dn (Elsel'i er. London) II)S'+ .

28 Figg is 13 N & Lewis J. I'wg In()rg (h Ul. 6 ( 1%'+ ) .1, 7.