Ray, Arabinda

Sathyanarayana, D. N.

English

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indianJournal of ChemistryVol.15A,July 1977,pp.591.595VibrationalAnalysisof Metal Complexesof·1,3-Dithiomalonamide& 2,4-DithiobiuretARABINDA RAY & D. N. SATHYANARAYANADepartmentof Inorganic& PhysicalChemistry,Indian Instituteof Science,Bangalore560012Received 20 October 1976;accepted9 February 1977The infraredspectraof Ni(II), Cd(II) andHg(II) complexesof 1,3-dithiobiuretandNi(II)andPd(II) complexesof 2,4-dithiomalonamidehavebeenassignedon thebasisof a normalcoordinatetreatmentfor thein-planevibrationsof thenickel(II)complexes.The assignmentof frequenciesofthemetalcomplexesarediscussedby referringto theassignmentsin relatedmolecules.TheRamanspectrumof dithiomalonamideis alsoreported.THE compounds1,3-dithiomalonamide(DTM)and 2,4-dithiobiuret(DTB) are structurallyanalogousto ~-dithioketoneswhich havebeen studied extensivelyI-3.But only recentlythe coordinationbehaviourof DTM and DTB hasreceivedsomeattention4-S.In generalthe infraredstudieson dithionamidesare meagrecomparedtothoseon monothionamides9-l2.Coupledvibrationsare expected for thioamides making empiricalassignmentsdifficult. In view of the fact thatexcepta few casesmajorityof reportsavailableonmetal-sL.lphurvibrationsare a resultof empiricalstudies13,we thoughtit worthwhileto study theIR spectraof somecomplexesof DTM and DTB.The infrared frequencieshave beenassignedwiththe help of normalvibrationalanalysismadeforthe nickel(Il) complexesusingWilsov'sGF matrixmethod and Urey-Bradley force function. TheRamanspectrumof DTM is alsoreported.MaterialsandMethodsDTB was preparedaccordingto a knownproce-dure14by passingH2S to an aqueoussolutionofdicyandiamide.It wasprecrystallizedfrom water,m.p. 181°. DTM was preparedby passingH2S toa mixtureof triethanolamineand malononitnleinethanol (9:>%) at roomtemperature15•It was re-crystallizedfrom ethanol,m.p.213°.Preparation of comPlexes: Dichlorobis(2,4-dithio-biuret)nickel(II) - This was preparedby a knownmethod5[Found:Ni, 14·82;C, 12'60;H. 2'60; N,21·23. Calc. for NiC12.2DTB:Ni, 14,68;C, 12·01;H, 2·50;N, 21·01%J.Dichlorobis(2,4-dithiobiuret)cadmium(II) - An etha-nolic solution of DTB was added to an aq.ethanolicsolutionof CdCl2 with constantstirring.Theresultingpaleyellowprecipitateof thecadmiumcomplexwas filtered, washedse\eral times withaq. ethanol and dried over concentratedH2S04[Found:Cd,23'92;C, 10·23;H, 1·82;N, 18·14.Calc.for CdCI2.2DTB:Cd, 24'79;C, 10·49;H, 2·20;N,18·52%J.Dichloro(dithiobiuret)mercury(II)- An ethanolicsolutionof DTB wasaddedto a solutionof HgCl2in ethanolwith constantstirring. The resultingwhiteprecipitatewasfiltered,washedwithethanoland dried over concentratedH2S04 [Found: Hg,48·5;C, 5'9,; H, 1'47;N, 9'77. Calc.for HgCl2.-DTB: Hg, 49·33;C, 5'90; H, 1'73;N, 10'33%].Dichlorobis(dithiomalonamide)nickel(II) -- Thiswaspreparedfollowinp:a knownprocedure5[Found:Ni,14'56;S, 31'73. Calc. for NiC12.2DTM;Ni, 14'76;S, 32·19%].Dichlorobis(dithiumalonamide)Palladium(II) - A me-thod similar to that usedfor Ni(Il) complexwasfollowed. The yellowcomplexformedwaswashedwith ethanol and then with acetoneand driedover COne.H2S04 [Found: Pd, 23·55; S, 28·13;N, 12'64;C, 16,41. Calc. for PdC12.2DTM:Pd,23'88;S, 28'93;N, 12'57;C, 16'20%].Analysis - The complexeswere an2lysed forthe metal contentsby standardmethods. TheC, Hand N analysiswereobtainedby micro-analysiscarriedout at theBhabhaAtomicResearchCentre,Bombay.Infrared andRamanspectra- Theinfraredspectraof thesolidsamplesin therange4000-400cm-lwererecordedon a Carl-ZeissURlO spectrophotometerwhilefor the IR spectrain the range250-400em-]wererecordedon a Perkin-Elmer521spectrophoto-meterin nujol mull and KBI. The laser Ramanspectrumof thesolidsampleof DTM wastakenona Cary 81spectrophotometerusingargonion laser,throughthe courtesyof Prof. ]. R. Scherer,USDepartmentof Agriculture,Albany, to whomourgratefulthanksare due. The spectraof DTB andNiCl2-DTBwerealsoobtainedfrom400to 40 cm-lon a BeckmanRIlC interferometer,throughthecourtesyof Prof. R. T. Bailey, the University ofStrathclyde,Scotland, UK, whom we gratefullythank.Normal coordinatetreatment- In orderto simplifythecalculations,1:1 modelsof thesecomplexeswereconsidered.Such an assumptiondoes not intro-duceanyseriousdifferencein the applicationof theresultsto the 1:2 complexes13.The 1:1 molecularmodels of both types ofcomplexesbelongto the point groupC2v and onlythe in-planetypeof vibrationsarecalculated. n,efrequenciesof interest belong to this category.591INDIAN J. CHEM., VOL. 15A, JULY 1977IThere hxe33 normal vibratiors for the 1:1 molecularmodel lor Ni-DTB of which the in-plane modes areJl2Ad~l1B2' The Ni-DTM complex bs 36 nonn,)lvibradons, and the in-plane modes arc 13A1+111>2modesJThe i symmetry coordinates were constructed asusual. ! The structure parameters (Fig. 1) for NiC12.2DTB I \vere taken from the palladium complex.The st~uctlireparameters (Fig. 1) used for Ni-DTMwerebhsedon thoseof thioacetamide16and I1ickcl(U)dithio~cetylacetonate2.The initial Urey-13ra(jeyforce ¢onstants for Ni-DT13 were transferred fromDT1317fand for Ni-DTM mostly from cyanothio-acetar~ide18(CTAM). Tbe force CCllstantsconnectedwith t~ecoorc1inatebondsweretaken from nickel(II)dithio~cetylacetonate2.The initial force constantswere rllOclificdprogressivelyto obtain a good agree-mellt !betwcen the obsen'CCl and c8lculated fre-quenciies. The fmal set of force constants for boththe cQm1Jlexesarc shown in Table 1. The forceconsta~1t~were found to be satisfactorily trans-ferabl¢. Notably, the force const<mtsare simibrfor bqth the systems.Resu1/tsand DiscussionDithio'tJiuretI n t~lecomulexesof DT13with cl loriclesof nicke1,cadmi~mamI mercury, metal ions are expected toco(;rd~natereaclily through the thiocarbonyl sulphuratomsf The observed and calculated frequenciesfor N~Cl2.2DT13along with their assignmentfrom~hep~'tential .(:ller~ydistributions (FED) ar~givenIn Ta le 2. Lhe mfrared lrequenClesof D113 andits m al compl xesare l sted in Table 3 and theassignPnentof the bands based on those of NiCl2.-20TBi is also indicated.Thd intensities of someof the infrared bands areweak~rin complexesas compared to those in theligancl and the bands in the complexestend to bebroad~ It is likely that in all the three complexesDT13 lis c>ctingas a bidentate ligand coordinatinE;through both the Sl lphur atoms as in the palladium(II) cr)mplex,whose structure bas been determinedby X-jra:ydiffraction met!OfF. The sredral features(a)(b)Fig. 1- Structureandinternalcoordinatesof (a)Ni-DTMand (b) Ni-DTB complexesof the metal complexes can be explained on thisbasis.The X-ray structure analysis has revealed thatDT13has trans-cisCS-NH-CS group19. On bidentatecoordination of DT13 through sulphur atoms, thespectrumLets somewhatsimplified probably becal;seof the apparent C2v symmetry for the coordinatedligard.-----t-.---------------------------------------------------------.----T~BLE1-- UREy-BRADLEYFORCECONSTANTS(mdyn/A)OF (a) DTB AND(b) DTM COMPLEXESOFNICKEL(II)!ab ab abHNH'5·525·02HHNH0,390·42FHNH,00-KNH, 6 HHNC3'3 5C'785C-4·25KCN6 606, 5NCN·1 FNCN1}(CN',4 NCS01NCScs'8·2'cS2 'CS·KNiS8'C4 CN'cc2'8C e e e4fNH,NJ-0·-0 Ni·22S iS,kt .-0·0495S iSCS iHNec0·20ce 0,87ccs· 8e s ,3e e040cec ·28HCC,3345H641*Non-Urey-Bradleyconstant.tIntramoleculartensionin mdyn/A.592ill I 11'11RAY & SATHYANARAYANA: VIBRATION ANALYSIS OF IR SPECTRA OF COMPLEXES*p.d.=percentagedeviation=(IVobs-Vcalc.!X 100)/vohs'tv =stretching, 8 =bending. r =rocking, a =asym-metric, and s =symmetric.tContributions from 8ring are combined.NH frequencies-" Dithiobiuretexhibitsfivebamlsat 3360,3280,3185,'3115and 3040cm-lassignableto NH2 and NH stretchingmodes,whereasin themetal complexesonly three bands around 3390,3300and3170cm-lareobserved.Similarly,insteadof two NH2 bendingmodesin DTB, at 1645 and1626 em-I,a singleband around1665 cm-l is ob-served in the nickel complex. These are inaccordancewith the changeof structureof DTBfrom Cs to C2v on bidentatecoordinationto themetal.CS and CN frequencis- Coordinationof thio-amidesthroughtheir thiocarbonylsulphuratomsresultsin th,edecreasein C=S stretchingfrequencyandanincreasein theC-N stretchingfrequencyIO,12.The bandsat 840 (doublet)and 780 cm-1in DTBcanbeassignedto C=S stretchingl7.The 840cm-lbandis loweredto 744,720 and720 cm-lin nickel,cadmium and mercury complexesrespectively.Similarly,the 780 cm-lbandshiftsto 720, 690 and660 cm-l respectivelyin the comlclexesof nickel,cadmiumand mercury. The decreasein the 780cm-lbandis in the expectedorderof the tendencyof the metalsfor sulphurcoordination,HG>Cd>Ni. TheC=S frequencyat 840cm-lis notsensitiveto thenatureof themetal. This maybeattributedto thefactthisbandis dueto a mixedmodehavinglessercontributionfrom C=S stretching. On theotherhand,thebandat 780 cm-lis dueto a nearlypure C=S stretchingmode. The assignmentof*.• =torsion, w =wagging, 7t=out-of-plane bending,Sk =skeletal.tNot investigated.the C=5 stretching frequenciesin the nickelcomrlexaround744 and 720 cm-l is supportedbythe normalcoordinatetreatment,and in the spec-trumof thenickelcomplex,thereis nOotherbandin the range900-750em-I. The largeshift in the840 and 780 cm-l bands of DTB in the metalcomplexesshould be ctttributed,in part, to thechangein structureof the ligandfrom trans-cis tothe trans-trans structurein the metal complexesand,in part,tothecoordinationofDTB tothemetal.The C-N stretchingfrequenciesin DTB may beassignedat 1495 and 1410 em-I, In the nickelcomplex,the C-N stretchingmodesoccurat 1490and1430cml, andthustheyarenot verysensitiveto coordinationFossiblydueto theirhighlycouplednature. However,the 1490 band of NiCl2.2DTBshifts to 1515 cm-l in cadmium and mercurycomplexes.Similarly,the 1430cm-l bandappearsat 1440 (1420) and 1470 cm-l in cadmiumandmercurycomplexesrespectively.Mainassign-ment'".HgCl2,DTBCdCl2.2DTBNiCl2.2DTB3390m 3360m5 sh3300mb278 bvNH2'vNH3170w1 5w1665s164281625vs18vs5149 vs2VaCN3 m4,CN142 s 1360sr z32 sh3265 126mbww05 w0s '09 s97 m7tNH744 s h7 0vCS7 0 m6 v1 s 860 vw.•NHz7tSk6sw8ring555 w5 hwNH5 5b4 SMS+8NCSmtt8Sk (ring)2 304vMS6NCS247tSkhTABLE 3- INFRAREDFREQUENCIES(cm-I) OF2,4-DITHIOBIURETAND ITS COMPLEXESAND,THEIR ASSIGNMENTDTB297 m258 vs240 s599 sb550 s515 sb470 s955 sh844 vs838 vs780 s735 s710 m640 s396 s1350m1285w1240mw1120s1010m3360s3283185mb3115w3040wb1645s1626ms1575ms1495mw1410mTABLE 2- INFRAREDFREQUENCIES(em-I) OFDICHLOROBIS(DITHIOBIURET)NICKEL(II)ANDTHEIR ASSIGNMENTObs.Calc.p.d.*Assignmentt(PED, %It339033940·1vsNH2 (99)33002 2'2NH (9 )17176H216651668 2 (84), vsCN (13)4950,8N 623rNH2 0550482 ' 41 , vs S 21 ,08NCS (15)7684,3S 1 , 8ring (23)1 6301·ring (5 ), vsC ' 6424 80M 4 N8NCS (17)2 697CS 55 M7 7 ( )0a 00)N 9 a 52 034 1 8NH (1$)56 6 ' (22)17' 2 4447 375' 8ring (15)52 6 . 8 C 0Mode593----_._._-~-~INDIAN J. CHEM., VOL. 15A, JULY 1977M-S~freql1CnCies- Thebandsat 420and304cm-Iaredu. to syn;~etricandasymmet.ricvNi-Smo~esrespecIv ly. Ih 420 cm-I band IS coupledwIthsymm~ricC-N stretchingandNCS bendingmodes,while Ithe 304.C~-I band ~s due ~o.a nearlypurea~ymmetncNl-S stretchmg. Tlus IS compat-iblewith thatin bis(dithioacetylacetonato)nickel(U),whereIfrom normalcoordinateanalysis2, the sym-metric!andasymmetricstretchingmodeshavebeenassignqd;nound390and300cm-I,respectively.Dithioi;nalonamideThepbservedandcalculatedfrequenciesforNiC12.-2DT1\1:!along with their assignmentsfrom thepotentfalenergyclistributionsaregivenin Table4.The Rjamanand infraredfrequenciesof DTM, to-getheriwiththeinfraredfrequenciesofthecomplexesaresh~wnin Table5, wheretheassignmentfor thefreque*ciesof the ligand moleculeis indicatedbycompatisonwith thoseof the complexes.C-NI and CO=S stretching vibratiotlS - A compari-son of!the C-N and C=S stretchingfrequenciesof01'1\1:<lndits complexesfor checkingfortheexpecteddecrea~ein the C=S frequencyandincreasein theC-N frbquencyon coordinationis not valid. Thereis greatdifferencein thegeometryof theligandwhenfree apcl complexed.The structureof DT1\1:hasnot b¢enestablishedby X-ray method. From acomparisonwith its oxygenanalogee20, malonamic1e,i Iit is inJ[erredthat thetwo H2N-C=S groul'sof D1'Marenot coplanar,whichgivesD1'1\1:a lowsymmetry,Cl.' qn bidentatecoordinationof DTlVI throughsulphuratoms,the effectivesymmetryof theligandis expectedto changeto C2v• Apart from coor-dination,the changein the symmetryof the ligandconsequentupon coordinationof DT1\1:may effectadditionalchangesin thebandpositionsof theligandin the complexes,as in DTB.In Ni(Il) and Pcl(U) complexes,the symmetricC-N stretchingmodearound1470cm-I is weaklycoupledto NH2 bending,while the asymmetricC-N stretchint around1520cm-I is coupledwithC-C stretchingami CH2 waggingmodes. A strongband at 1460cm-] in DTM can,be attributedtoC-N stretchingin agreementwith an earlierassign-menpo.A shLJ,fpintenseband around 810 cm-I in theligandwasassii,nec1by JensenandNielsen10to C=Sstretching. Unambiguousassi~;mnentof the infra-red bands in the region 850-650cm-I in thecomplexesof D1'11appearsto be difficult despitethe normal coordinate calculations.The ban(~saround820and 690 cm-] in the nickel complex,and around 840 and 720 cm-Iin the palladiumcomplexhave similar shape and intensity. Thebandsaround800and 700cm-1in the complexeshavebeenfavouredby normalcoordinatetreatmentto be predominautlyasymmetricand symmetricC=S stretcLingmodesrespectively.TABLE 5- VIBRATIONALFREQUENCIES(em-i) OFDTM AND ITS COMPLEXESAND THEIR ASSIGNMENTCalc. p.d. Assignment(PED, %)*32040·1vsNH2 (100)2998NH2 (10 )30,0C ( )1662/l (77), vsCN (20)4793CN 64), /lNH2 130162 95321 4rNH 42), C (25),vsCS (12)02 39 327 31'9S (62), vsC (14)·3ring 73182 1MS(52), /lNCS 4463, 8870 C 5 MS 63204a 9958 Va 723 a 13wCH2 (13)15w r29 ,95'9C 47 , r H2 785 64 15112i SV S 5*For symbolsseeTable 2.132512851042820800510332292(rABLE 4 - INFRAREDFREQUENCIES(em-i) OFNiC12.2DTMAND THEIR ASSIGNMENTMode Obs.Ai 320030002930166514751410134010106906084273603083200300016651520594l-lilRAY & SATHYANARAYANA: VIBRATION ANALYSIS OF IR SPECTRA OF COMPLEXESMetal-sulPhur vibrations- In the nickelcomplex,the bandsat 427 and 293 (calc.) cm-1are pre-dominantlydueto symmetricandasymmetricNi-Sstretching modes respectively.These are com-patiblewith Ni-S stretchingvibrationsaround390and 295 cm-1reportedin the case of nickel(II)dithioacetylacetonatell.The symmetric Pd-Sstretchingmodeis coupledwith NCS bendingandhas contributionsin the 420and 280 cm-1bands,larger contributionbeingin the latter band. TheasymmetricPd-S stretchingoccursaround265cm-l.This assignmentcomparesfavourablywith Pd-Sasymmetricand symmetricstretchingmodesas-signed around 285 and 380 cm-1respectivelyinpalladium(II) ditliioacetylacetonatell.References1. Cox, M. & DARKEN, J., Coord.chern.Rev., 7 (1971),29;LIVINGSTONE, S. E., Coord.chern.Rev., 7 (1971),59.2. SUMAN, O. & FRESCO, ]., Inorg. Chern.,8 (1969),1846.3. SUMAN, O. & FRESCO, J., J. chern.Phys., 54 (1971),734.4. PEYRONEL, G., PELLACANI, G. C., BENETTI, G. &POLLACCI, G., J. chern.Soc. Dalton Trans., (1973),879.5. PEYRONEL, G. & PIGNEDOLI, A., Proc. XIth InternationalConf. 012 Coord.Chern.,Haifa and Jerusalem,1968,290.6. PELLACANI, G. C., PEYRONEL, G. & MALAvAsI, W.,Inorg. chirn.Acta, 8 (1971),49.7. GIRLING, R. L. & AMMA, E. L., Chern.Cornrnun.,(1968),1487.8. LUTH, H., HALL, E. A., SPOFFORD (III), W. A. & AMMA,E. L., Chern.Cornrnun.,(1969),520.9. WALTER, W. & STAGLICH, P., Spect,·ochirn.Acta, 30A(1974),1739.10. JENSEN, K. A. & NIELSEN, P. H., Acta chern.scand.,20 (1966),597.11.DESSEYN, H. 0., VANSANT, F. K. & VAN DER VENKEN,B. J., Spectrochirn.Acta, 31A (1975),625.12. RAY, A. & SATHYANARAYANA, D. N., Indian J. 'Chern.,12 (1974),1092.13. CORMIER, A., NAKAMOTO, K., CHRISTOPHLIEMK, P. &MULLER, A., Spectrochirn.Acta, 30A (1974),1059.14. KURZEV, F., Org. Synth., 35 (1955),69.15. LEHR, H., GUEX, W. & ERLENMEYER, H., Helv. chim. "Acta, 27 (1944),971.16. TRUTTER, M., ]. chern.Soc., (1960),997.17. RAY, A. & SATHYANARAYANA, D. N., Spectrochim.Acta,31A (1975),899.18. RAy, A. & SATHYANARAYANA, D. N., Bull. chern.Soc.Japan, 46 (1973),1969.19. SPOFFORD, W. A. & AMMA, E. L., ]. Cryst. Molec.Struct., 2 (1972),151.20. CHIEH, P. C., SUBRAMANIAN, E. & TROTTER, J., J.chern.Soc., A, (1970),179.I---.-----'""...• d~

Vibrational Analysis of Metal Complexes of 1,3-Dithiomalonamide & 2,4-Dithiobiuret

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Vibrational Analysis of Metal Complexes of 1,3-Dithiomalonamide & 2,4-Dithiobiuret

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