Gowda, B. T.

Mahadevappa, D. S.

Murthy, A. S. A.

English

NOPR

IndlaJl .Journal of ChemistryVol. 14A, December 1976, pp. 985-987Some Thiosemicarbazide Complexes of Pt (II) & Pd(lI)D. S. MAH.<\DEVAPPA, B. T. GOWDA & A. S. A. MURTHYDepartment of Postgraduate Studies & Research in Chemistry, Manasa Gangotri, University of Mysore, Mysore 570006Received 17 November 1975; accepted 17 March 1976Ionic complexes of Pt(II) and Pd(II) with thiosemicarbazide (L) of the general formulaML,X2 where X = CI, Br, I, CN, CNS, N03 or 1804 have been prepared from H2PtCla.xH,O andPdCI, and using the method of substitution of the anion in ML2CI2• The preparation of twoneutral complexes of the type M(L- H). has also been described. Elemental analyses, magneticand conductance measurements, UV and IR spectral data have been obtained. The complexesare probably square-planar. Existence of cis-trans isomerism among the complexes has beendemonstrated.METAL complexes with nitrogen and sulphurdonors have been the subject of two recentreviews--". In continuation of our earlierwork on thiosemicarbazide (tsc) complexes of zincgroup metals'', we are reporting here the results ofour studies on complexes of Pt(II) and Pd(II) withtsc. Although the preparation of some of thesecomplexes has been mentionedv" in literature.detailed studies have not been carried out.Materials and MethodsThiosemicarbazide (tsc) was a Merck reagentand it was recrystallized before use, PdCl2 andH2PtC16.xH~O (] ohnson Matthey] were used assuch. Magnetic measurements (250 ± 2"') on thecomplexes were carried out using the Gouy method.X-ray powder patterns were obtained using Debye-Scherrer camera of diameter 114·6 mm with Co-K;().= 1·7902 A) radiation. Other experimental detailshave been reported elsewhere".Preparation oj complexes: cis-PtL?('l"-An ethanolicsolution of HzPtCI6.xH20, was added dropwise toa hot solution of the ligand in minimum amount ofethanol in 1:2 ratio (metal-ligand). A buff-yellowcomplex separated from the solution after stirring.It was filtered, washed with hot ethanol and driedover P205 in vacuo (Found: C, 5·23; H, 2·10.Calc.: C, 5·35; H, 2·23%).trans-PtL~Cl2 was prepared by mixing the re-actants in ethanol in cold (Condition.cis-PtL2S04• cis-PtL2(N03h, transPtL2Br~. trans-ru.,r; tram-PtL2(CN)2 and trans-PtL2(CNSh \~'ereprepared by adding saturated aqueous solutionsof the respective alkali sulphate (or 1:1 H2S04),nitrate (or 1:1 HN03), halide, cyanide or thiocya-nate to an ice-cold saturated aqueous solution ofds-PtL.Clo in the stoichiometric ratio. The solidsseparated -after stirring were filtered, washed withice-cold water and recrystallized from aqueoussolution.cis-PtL"S04 and cis-PtL2(K03h can also be preci-pitated by adding 1:1 H2S04 or 1:1 HN03 drop-wise to a hot 1:2 aqueous mixture of H2PtCI6·xH20and the ligand.trans-bisithiosemicarbazides Pd(II) chloride - Asolution of thiosernicarbazide 12 moles) in 2MHCl was added to a hot solution 'of PdCI; (1 mole)in 2M HCl with constant stirring. The complexwhich separated was filtered, washed with O·IMHCI and dried over P205 in vacuo (Found: C,6·72; H, 2·71. Calc.: C, 6·68; H, 2'78%).The preparations of trans-PdL2S04, trans-PdLz-(N03)z, trans-PdLzBrz, trans-PdLzIz• cis-PdL2(CN)2and cis-PdL2(CNS)2 were similar to those of thecorresponding platinum complexes described above.trans-PdL2S04 and trans-PdL2(N03)2 can alsobe precipitated respectively by adding tsc in 1:1H2S04 or 1:1 HN03 with constant stirring to a solu-tion of Pcl(OH)2 dissolved in 1:1 H2S04 or 1:1HN03, in 2: 1 molar ratio. Corresponding ciscomplexes were obtained at higher temperatures.tra-us-Pt(L-H)2 and trans-Pd(L-H)2 were preparedrespectively by the addition of excess 1M ammoniato aqueous solutions of the corresponding chloridecomplexes.Results and DiscussionThe analytical data (Table 1) of the complexesindicate the formation of two types of complexes;M(LhX2 and M(L-H)2 where M=Pd(II) or Pt(II),L=tsc and X=various anions.The platinum complexes with the exception ofPtL2S04 and Pt(L-Hh are soluble in water, whilethe palladium complexes with the exception· ofPdL2S04• PdL2(CN)2 and Pd(L-H)z are moderatelysoluble in water. All the complexes are insolubleill common organic solvents.Molar conductance measurements on 10-aMaqueous solutions of the complexes at 25° showthat the complexes are 1:2 electrolytes" (Table 1).The electrolytic nature of the complexes was furtherverified by -ion exchange experiments.All the complexes are diamagnetic, as expectedfor square-planar complexes of Pt(II) and Pd(II).UV and visible spectral data of the complexeshave been obtained. The bands around 42 and48 KK could be attributed to intra-ligand transitions,while those around 38 KK could be the charge-985INDIAN J. CHEM., VOL. 14A, DECEMBER 1976TABLE 1 - PHYSICO-CHEMICALDATA OF THE CO:.!:PLEXESComplex Found (Calc.), % Decomp. AMtemp. (ohm+ cm-l mole+)M S N X °Ccis- PtL2Cl2a 43·30 (43'50) 14·44 (14,31) 18·56 (18'74) 15·84 (15'83) 274 271trans-PtL2Cl2b 43-60 (43-50) 14040 (14,31) 18·97 (18'74) 15·74 (15·83) 271 269trans-PtLaBr2a 36'86 (36,32) 12·09 (11,94) 16·10 (15,64) 29·45 (29'75) 294 268trans-PtL.Iaa 30·65 (30·91) 9·91 (10,16) 13-52 (13'31) 40·62 (40,21) 250 264trans- PtLa(CNhC 45'82 (45-43) 14-68 (14'93) 26·10 (26'09) 12-00 (12-12) 250 231trans-PtL,(CNSl.d 40·00 (39·53) 26·23 (25'99) 22·80 (22'70) 23·14 (23,54) 185 196cis-PtL2(NO.l.e 38·66 (38'91) 13-00 (12'79) 22·53 (22,35) 279 249cis-PtL2SO,e 41-48 (41'21) 20·51 (20,32) 17·96 (17-75) 20·35 (20,28) 267trans-Pt(L-H).f 51·23 (51'97) 16·92 (17,08) 22'20 (22-49) - 235trans-PdLICl.g 29·55 (29·83) 17·33 (17-80) 22·93 (23,36) 19·78 (19,74) 271 273trans-PdL.Br3h 23'86 (23'72) 14·65 (14·30) 18·45 (18·74) 35·14 (35·63) 280 258trans-PdL212i 19·50 (19-61) 11·90 (11'82) 15-47 (15-49) 47·11 (46'79) 235 243cis-PdL2(CN)sh 30·93 (31'23) 18·92 (18,82) 33·00 (32·89) - 209cis-PdLI(CNS)ld 26·19 (26'28) 31·98 (31·68) 27·52 (27-68) 28·18 (28·69) 169 222cis-PdL2(N03),g 25·96 (25,78) 15·25 (15,54) 26·50 (27,15) 272 239trans- PdL2 (N03).b 25·38 (25'78) 15·45 (15'54) 26·70 (27,15) 274 243cis-PdL.50,i 27·65 (27-62) 25·69 (25·00) 22-27 (21'84) 25-40 (24,97) 262trans-PdL2SO,b 27'76 (27-62) 24-87 (25'00) 21·63 (21,84) 25·34 (24-97) 260trans-Pd(L-Hl.d 36·94 (37'11) 22·65 (22,37) 29'19 (29-44) 201a = buff, b = light buff, c = greenish white, d = greenish yellow, e = yellowish white, f = silky blue, g = lightorange-yellow, h = orange-yellow, i = orange.transfer bands of the groups S-Pt and S-Pd. Thecommon bands around 28·5 and 23·5 KK maybe ascribed to d-d transitions characteristic ofsquare-planar complexes.Tentative assignments of the IR bands in typicalcases, based on previous work3,5,7, are shown inTable 2.Upon complexation \lNH modes of the ligandat 3389, 3285 and 3194 crrr" move to lower regionsin the ionic complex while a shift towards higherwave numbers is noticed in the case of neutralspecies, M(L-Hh. The formation of neutral com-plexes by dissociation of proton from the NH2group of the ligand may lead to strengthening ofthe remaining NH bond. The other site of co-ordination is thiocarbonyl sulphur atom as indicatedby the downward shift of \I C=S by ,....,100 crrr 'from the position observed in the ligand=". Twostrong bands at 1642 and 1623 crrr ' (bending modes?of NH2 or combination of deformation mode ofNH2 and the amide-II band'") are not much affectedby complex formation". On the other hand, astrong band observed at 1531 em:' in tsc, attributedto a coupled vibration of a NH rocking mode andCN stretch (~ NH+\lCN), is raised to higher fre-quencies in the ionic species, while it is unchangedin the neutral comolexes. This increase is C'J:n-patible with coordin~tio:1 through sulphur in whichcase the double bond character of the C~ bni iseXPJcted to increase thereby 3.ff;:;tin; th s C) rtri-bution of \lCN in the io.iic c i:n )lexe;. Of the twomoderately strong ban Ls at 1+S7 an I 132'J crr '(\lC~+X:-lt'J2+\lCS),the former m ives to 1.1 N er lre que.icyre'510.1 while the latter m )'Ii!3 to higher frequencyregioal0. The ba-i Is at 129} c n-1 (vc:-<+vcs) and1172 and 10}} ern? (X.'IH,+~-"H,) are 0.11y slightlyaffected by complex form rtioa. But a VdYimportant feature of the IR spectra of the neutral986TABLE 2 - INFRARED BAND POSITIONS (cm-') Oll'THIOSE:.!:ICARBAZIDEAND ITS COMPLEXEStsc fralls-PdL.CI. cis-PtL2SO, trans-Pd(L-H).3389S 3354S 3315VW 3456S3285m 3248S 3208VW 3287m3194m 3142W 3150VW 3215W(b)1642S 16485}d 1658V5 16405}d1623S 1621S 1600S15315 1580VW 1571VW 1531m1487m 1+50S 1467S 1458VW1326m 1384m 1423m 1317V512905 1342m 1383m 1231511725 12395 12755 114751158m1000S 1017VW 1098S(IJ) 1009VW958V58195 700S 7005 70056505 6215(b) 6145 674m5045 498VW 511W 5015431m 490VW 433VS455W440VWcomplexes is th i appearance of a strong band at958 cm ", This is m ost likely the N-N stretch dueto the elJ.lg.lticl.l of ~~-~.p bo.id and a charge locali-z atio.i 0.1 the c-~: brad ',5,11. Bands around 650cm! a·1-1b elow in the ligand are assigned to skeletalvibrations l!.Evidence for cis-trans isomerism among theco.nplexes Ins been obtained from the IR data.Two sharp bauds are shown by the trans isomeraround 34J}-3000 cm' while the cis-isam('r showsonly 3. broad band. Also the trans isomer showsa doublet band around 1600 crrr" while a sharpsin jle broad band is observed for the cis-isomer.Further, the trans compound is characterized bya single distinct peak at ,...,,435 crrr" while a numberof peaks are fo.m.l in this region for the cis form.MAHADEVAPPA et al.: Pt(II) & Pd(II) COMPLEXES OF THIOSEMICARBAZIDEH H H From the physico-chemical data obtained for theI \ / /H complexes it may be safely assumed that the com-N- N~ /S=C-N <,H plexes are square-planar, with the metal ion co-H I M2+ I ordinating through the sulphur and nitrogen atoms"N - C= s / ~ N-N of the ligand. Structure (I) is proposed for theH/ /\ I trans ionic complexes. Similar structures can beH H H written for the cis form of the ionic complexes andtrans form of the neutral complexes.II IX-ray powder patterns obtained broadly suggesta monoclinic crystal structure for the complexesand support the IR evidence. While the transform shows only a few lines in its diffraction pattern,a large number of lines were obtained for the ciscompound. The large number of bands and linesobserved for the cis compounds could be attributedto the absence of centre of symmetry in these mole-cules.H is to be noted that in the present studies, itwas possible to obtain the cis form of ~tL2Cl~,while Haines and Sun5 were unsuccessful III theirattempts to prepare this compound.. Contraryto expectations, it was found that the css form ISstable for several months. In the method of pre-paration based on anion substitution, ~ith cis-PtL2Cl2, using n-. 1-, CN- and CNS- IOns ,~hetrans form of the complexes was obtained. WithNO; and S01- ions, only the cis form was obtained.However, the neutral complexes were obtained inthe trans form. Similarly with trans-PdL2Cl2, transforms of the complexes were obtained when Br,I-, NO:; and SO~- ions were used. The neutr~lcomplex was also obtained in the trans f0!ID' C1Sforms are obtained when CN- and CNS- IOns areused. It is likely that there is a preference for thetrans arrangement with some. of these anions, .whichmay be due to the interaction of the latter In theaxial positions of the' molecule.AcknowledgementThe authors thank Prof. D. Devaprabhakara.Indian Institute of Technology, Kanpur, and Prof.A. K. N. Reddy, Indian Institute of Science,Bangalore, for elemental analyses and IR spectrarespectively and Prof. G. K. N. Reddy, BangaloreUniversity, for helpful discussions. One of them(D.S.M.) gratefully acknowledges financial assistancein the form of a special research grant from theUniversity of Mysore, Mysore.References1. ALI, M. A. & LIVll'iGSTOl'iE, S. E., CeCfd. chcm, Rev.,13 (1974), 101.2. CAMPBELL, M. J. M., Coord. chem. u«, 15 (1975), 279.3. MAHADEVAPPA, D. S. & MURTHY, A. S, A., Aust, j.Ch em . 25 (1972), 1565.4. ]El'iSEl'i, K. A" Z. anorg, allgem. Che'I1" 221 (1934), 6.5. HAll'iES, R A, & SUN, K. K. W., ce«. J. cie«. 46(1968), 3241. . .6. JONES, M. M., Elementary cOOrd111Q/zol1 chemistry(Prentice Hall, Englewocd Cliffs, N]), 1964, 254.7. BURl'iS, G. R, Inorg. Chem., 7 (1968), 227.8. SUJUKI, I., Bull. chem . Sec. japan, 35 (1962), 1286.9. MASHIMA, M., Bull. chem . Sec. Japan, 37 (1964), 974.10. CAMPBELL, M. ]. M. & GRZESKOWIAK, R, j. chem,s«. A, (1967), 396.11. CAVALCA, L., NARDELLI, M. & FAVA, G" Acta Crystallogr.,15 (1962), 1139.12. NAKAMOTO, K., Infrared spectra of inorganic and co-ordination compounds (John Wiley, London), 1963,146-51.987

Some Thiosemicarbazide Complexes of Pt(II) & Pd(II)

http://nopr.niscair.res.in/bitstream/123456789/53975/1/IJCA%2014A%2812%29%20985-987.pdf

Some Thiosemicarbazide Complexes of Pt(II) & Pd(II)

Abstract

Similar works

Full text

Available Versions

NOPR