ions containing nitrogen

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or square planar geometry around transition metal ions. i nteresti ng spectral and magnetic properties. In addition, dithiolates have a number of industrial and.
Indian Journal of ChelTli stry Vo l. 4 1A. November 2002, pp. 2282-2284

Synthesi s and characterization of ionic heterobimetallic comp lexes of Ni(ll) , Cu(I!), Zn(II ) and Cd(II) ions containing nitrogen and sulphur donors M K Singh*, R Laskar & A Das Dcpa rtm cnt of Chcmi stry. T ripura Uni versity. SlII'ya maninagar 799 130. Tripura. Indi a

mi xed 1, 1- and 1,2-dithio comp lexes of co balt and iron . But, th ere is no report on the reacti on products o f aliphatic diamine coordinated copper(ll ) cati ons with sulphur coordinated nicke;(II), zinc(l£) or cadm ium(lI ) anions. [n vi ew of the above, we represent our result of inves tigati ons on the ionic heterobimetallic co mpl exes invol ving complexed cations and cO l11plexed anion in thi s note.

R('('C'il 'Ct/ II FebJ'/l{{i'v 2()()2; rC'l'i.l'ed 17 May 2(){)2

Experimental nUlllber of ncw ioni c heterobillleta llic comp lexes of co ppC:I·( II ). nidel(II ). zine( II ) and cadmiurn(II) ions o f th e co mposit ions. ICu ( N-NhIlM (S- S )~ I I -N = eth y lenedia mine (cn). tr imeth y lenediaminc ( tn) ; M = N i(II ), Z n(II ) or Cd(l l ) ; S-S = 2 1. I -di cy anocth y lcne-1.2-dithiolat e, (C hC=CS ~>. (i-MNT - ) I have bee n sy nthes ized by th c react ion of nitrogen coord inated mctal ca ti ons and sulphur coordinat ed metal ani ons in aq ueous/ aqu co us- acc tone! mcdium and chal'ac tcrizcd. Complexed meta l cati ons and complc xcd me tal ani ons required for the sy nthesis ha ve been pI'epared ill .I'illl by th e kn own literature procedures. T he lI10lar co nductan ce dat,\ reve al th at th e co mp lexes ha vc I : I electro lytic nature in DMSO so luti on. Magneti c and c/ec tl'Oni c ' peCi ral studi es suggest four-coordinated metal io ns in these l·omplexcs. Infrared spec tral studics suggest bidentat c ehelating bcha vioul' of eth y lenediami nc. trilTl cth y lcned iamine and 1, 1diey anoe th y lenc-2,2 -dithiolat c ion in th eir co mplcxes . A

T he coo rdinati on chem istry or tran siti on as we ll as non-tran siti on metal dithiolates has been an area of interest I'or se ve ral years 1.2 Recentl y, th e role of dithioligands have been ex pl ored in th e design of man y elec tri ca ll y co nducti ng molec u lar sol id s ~-6. The interes t in thi s area stems fro m vari ous reasons such as stabili zati on of transition metal ions in its unusunl ox idation stat es, facile redox beha viour, stabili zati on or square planar geo metry around transition metal ions. i nteresti ng spec tra l and magneti c properties. In add it ion, dithiolates have a number of industri al and biologica l applicati onsc.7 A mong I , I-dithi oli gands, I , l -di cya noethyl ene-2,2dithiolate ion shows exc itin g coo rdinati on properti es by virtue of its chelating and bridging behavi ou r. The 2 chelating and bridging nature or i-M T - ion has been fou nd in its binary , ternary and heterobimetallic OS ~ 0 . to·tnc Iudes co mp Iex es-·' · . ur ear I'IeI' co mmunl.cat ton th e studie s on reac tion o f eth ylened iamine w ith K ~ Zn(i-lVINT)2 and K 2CcI (i-M NT)2 whi ch y ielded mi xed li gand as wel l as ioni c complexes. McCl everty 2 el al. have obtained and characteri zed a series of

A ll chemical s we re GR (M erck) or eq ui va lent grades and were used without further puri fi cati on. ll K2i-MNT.H 20 was prepared by literature proced ure . Sylll hesis

of COli/pI exes

Co mpl exes Cu(en)c(NO] )2.2 H20 , Cu (tn hC NO.1h2H 20 and K2M (i-MNTh [1VI= i(ll ), Z n(ll ) or Cd( II ) 1 required fo r th e sy nthes is or comp lex es ha ve been 10 17 t ' prepared by kn own literature procedtt res . -, ".

/ Cu(N-Nhl /M(i-MNTh J /N-N =

ell, til ;

M = Ni(II).

ZII(//) or Cd(II)}

Th e co mpl exes were prec ipitated by the reacti on of equimolar aqueous/ aqueous-acetone soluti ons of Cu(N-N hCNO]h 2H 20 and K 21V1(i-MNT )2. Al l sy nthes ized complexes were filtered through sucti on, was hed w ith water, aleoh I, ether and dried ill vacl/ o over CaCl c. All th e compl e:-< es were anal y ed for their metal and sulphur con tents followin g t2 after destroy ing standard literature proced ures organi c matters. Sulphur was determined as BaSO~ . Carbon, hydroge n and nitrogen we re determined microanaly ti ca ll y . The molar co nductan ce va lues or th e com pl exes in DMSO at 10-.1 M conce ntrati on were measured w ith a WTW co nduct ivity meter. Infrared I spectra were recorded in nujol (4000-200 cm - ) and t KBr pellets (4000-400 cm- ) on a Perk in-Elmer I nfrared spec troph otometer.

Results and discussion The analytical data and stoichiometri es of th e comp lexes reveal the formati on o f tran siti on metal co mplexes in vo lving Cu( ll ) and N i(ll ),' Zn (H) or Cd(lI) ions o f th e com positi on [Cu(N -N h lfM (SSh HN-N= ethyl enediamine (en), trimeth y lenediamine (tn) ; M = N i(lI), Zn ( 11) or Cd(l l); S-S = I , I-di cyano-

'y \

NOTES

228 3

Tabl e I --Charact eri za ti on data o f th e co mp lexe s Dec. T emp .. uC (ty, Y ield )

Cu

Ni /Zn/Cd

S

N

C

H

2 10 (70)

II .SO ( 12.1 3)

10.92 ( 11 . 12)

24.01 (24.49)

2 1.2 1 (2 1. 54 )

27.32 (27 .52)

2.9S (3. 0R)

65.20

1. 70

Dirt y ye llow ICu(enh lrZ n( i-M NTh J Dark brow n

225 (65)

12.30 ( 11.9R)

11 .76 ( 12.32)

23,S2 (24. IS )

20.77 (21. 27)

27 .01 (27 .18 )

2.S I (3. 04 )

78.30

1.74

ICu(en), JfCd( i-M NThJ Pinki sh brown

201 (82)

11.41 ( I 1.(0)

19.75 ( 19.47)

2 1.93 (22.2 1)

I S.99 ( 19.54)

24.50 (24. 96)

2.6 1 (2 .79)

70.10

1.73

ICu(tn )211 N i(i -MNTh l G reeni sh yell ow

240 (7 5)

11.23 ( 11.52)

10.2 1 ( 10.64)

23,0 I (23.24)

20.14 (20.4-1 )

30. I S (3 0.4S)

3. 05 (3.65 )

66.42

1. 72

fCu(tn h IlZn( i-MNTh l Brow n

2 15

11.78 ( 11.38)

10.62 ( 11.70)

22.34 (2297)

19.R7 (20 20)

29. S7 (3 0.11 )

3. 12 (3. 61 )

75.20

1.94

(GO)

ICu(tn ), IlCd( i-MNT)2 1 Maroon

205 (72)

10.1 2 ( 10.49)

I S.O I ( 18. 56)

20.R9 (2 1. I S)

18. 13 ( 1863)

27 .02 (27 .77)

3 01 (3.33 )

67.25

1.78

Comp lex (Co llllll')

ICu(e n)2 11 N i(i-M NT),l

Found (Cal ed.). %

eth ylcne-2,2-dithi olate (i-MNT2 -)1 and th eir compositions are presented in Table I . The co mpl exes are inso lubl e in water and co mm on orga ni c so lve nts but so lub le in DMSO and DMF. The electrical conductance val ues of th e complexes in DMSO solution li e in the range 65 .2 -7 8.3 mh o c m2 mo r l are electrolytic naturel.J. The consi stent with I: co mplexes decompose in th e te mperature range 20 1240°C. Magneti c moments of th e comp lexes show th e val ucs in th e range 1. 70-1 .94 B.M . correspo ndin g to one unpaired elcc tron . All comp lexes except fCu (tn h llCd(i-MNThJ show three electronic absorption bands in th e ranges 1562518382. 21978-22727 and 25974-28571 cm- I: [Cu (tn h JfCd (i-M Th] shows onl y two absorption bands at 15625 and 25974 cm- I. The square planar Ni (lI ) co mpl exes ex hibit abso rption in th e vis ibl e region betwee n 15000-25000 1 CI11 - and in many cases a second more intense band bctween 23000 - 30000 cm- I. These are refe reed to as v I anc! V2 wh ich have been ass igned as I A I g ---7 I n I g and I A lg ---7 I A ]g respec ti ve ly. The lCu(en)21fNi (i-MNT h J and lCu(tn h ]1 Ni( i-MNThl ex hibit two bands at 15625, 2 1978 and 15649, 22026 CI11 - 1 respec ti vely which are within the range for square planar geo metry around Ni(1l) 15 ion in the co mpl exes . The possibility of tetrahcdral or octah ed ral arrangement around Ni(ll ) in th esc compl exes may be rul ed out as no electro ni c absorption bands occ ur bel ow 10000 em- I.

1

AM

~ efr

(Q - I em 2 ( BM ) mol- I)

The Cu(ll ) co mpl exes are also expected to show two bands in the region 14000-25000 cm- I which is an ovcrlapping region with that of th e Ni(ll ) co mpl exes . The co mpl exes rCu (N-N h l[M (i-M Thl [N-N= en, tn ; M = Zn(l l) or Cd(ll)] show bands in th e region ex pec ted for square planar geo metry' 6 whil e th ese bands In [Cu(enh H i(i-MNThl an d [Cu(tn h ][Ni (i -M Th J co mpl exes are overlappin g with that of Ni(ll ) square planar complexes. The magnetic mome nt va lues and elec tron ic spec tral bands suggest sq uare planar arrangement aroun d Ni(l l) and Cu(ll ) ions and tetrahedral arrangemen t around Zn( ll) and Cd( ll ) ions in th ese com pl exes. The infrared spectra of th e compl exes sy nth es ized have been interpreted In th e li ght of earli er . . IJ 17- on . .on meta I d'Itl1 I' 0 Iates. Inves ti. gation s I I .. - on tran siti The i-MNT2- li ga nd ion may be described by reso natin g structures (I ) in its comp lexes whi ch und ergoes parti cular vibration s and co ntributes certain peaks to IR spectra . The elec tron delocali sati on in th e chelated i-MNT2- rin g leads to the couplin g or vibrational modes so that few bands in I R spec tra represe nt pure vibration s. Accordingly , assi gn ment s ha ve ge nerall y been given to those vibrations which make th e most dominant contribution to eac h IR band. The IR spec tra of co mpl exes di splay ch~lracteri stic stretchin g frequencies associated with C N, C=C, C-S and M-S from i-MNT2- and N-H and M- I vibrati ons from diamin e moi eti es.

=

IN DI AN J C H EM, SEC A , NOVEMBER 2002

2284 ,,

1 - ('

/

/~- .-

N"C

(a)

(b)

(c)

(I)

Th e v(C=N) vibrati ons appearin g at 2 195 cm - I with a shoulder at 2200 cm- I in K2 i-MNT is observed in the range 2 197-2213 CI11 - 1 in these comp lexes. The v(C=C) abso rpti on band at 1360 cm- I in K2i-MNT is observed in th e range 1373- 1385 cm- I . The pos iti ve shifts obse rved in stretchin g frequ encies o f C=N, C=C sugges t that reso nan ce form (a) (I) is more dominant in th ese com pl exes or l-MNT 2- li gand ion. A band at 960 with a should er at 985 cm- I on th e hi gher freq uency side is obse rved in th e IR spec trum of K2iMNT due to =CS 2 group. The corresponding band in th e co mpl exes is round in th e ran ge 924-957 cm- I . The v(C-S) occu rrin g in th e spectrum of K2i-MNT at 860 cm- I appears in 864-895 c m- I reg ion in the co mplexes indicati ng sy mm etri ca l bonding of both sulphur atoms to meta l ions. Similar bondin g hehaviour of i-MNTc- ion is reported l 3 in K2[Ni(iMNT)21 where a sin gle band due to v(C -S) band is observed at 900 cm- I . The infrared spect ra of the co mpl exes co ntai n bands characte ri sti c of coordin ated neutral nitrogen bases as repo rted earli er indi catin g bonding through the bas ic nitrogen ato m( s)1 7. 1'). The non-li gan d bands obse rved in th e regions 3 10-390 and 220-320 cm- I 111 lhe spec tra of comp lexes are tentati ve ly ass igned to v(M-N) IX( and v(M- StO() modes res pec ti. ve Iy. Based on sto ichi ometri es and spect roc hemical studi es described above, th e tentati ve ly proposed structures o f the co mpl exes are II .

Acknowledgement The auth ors are gra teful to Tripu:-a Universit y, for providing financial support from UGC unass l ~ n ed grants under minor research pro ject. The help received from the Head , Departmen t of Chemistry , Calc utta University for recordin g UV-v isible spec tra in so lid state and Head, RSIC , Shillong for record in g IR spectra is al so acknow ledged.

References Coucouva ni s D, Prog Illorg Chelll. Vol I I. 26 ed ited by S J L ippa rd (Intersc ience. New Yo rk ). 1