Agarwala, U.

Nigam, P. C.

Pandey, Govind S.

English

NOPR

__ n ~_.· n ~· 1indianJournalof ChemistryVol. 15A,June 1977,pp. 537-541ComplexingBehaviourof 2-ThiooroticAcid: Complexesof Co(lI),Fe(II), Rh(III), Pd(IV) & Pt(IV)GOVIND S. PANDEY·, P. c. NIGAMt & U. AGARWALAtDepartmentof Chemistry,Indian Intsituteof Technology,Kanpur208016Received15 March 1976;accepted13 January 1977Complexesof 2-thiooroticacidhavebeenpreparedwithCo(II), Fe(II), Rh(III), Pd(IV) andPt(IV). Their probablestructureshavebeenpostulatedon the basisof magneticmoments,electronicandinfraredspectra.Crystalfieldparametershavebeencalculated.INour previous communications1•2we haveshownourinterestin thestudyof thecomplex-ing behaviourof 2-thiooroticacid (I):COOHIC/,H-N C-Hr IC CI""/,N 0IH(I)This compoundand its salts have a numberoftherapeutic3-5and industrial6-sapplications.In this paperthe preparationand spectralandmagneticpropertiesof the complexesof Co(II),Fe(II), Rh(lIl), Pd(IV) and Pt(IV) with (I) arereported.MaterialsandMethodsAll the chemicalsusedwereof AR or CP grade.Z-Thiooroticacid (I) (abbreviatedas H2tot) waspreparedby the methoddescribedin the litera-ture9-11.The ammoniumand sodiumsaltsof (I),abbreviatedas AmHtot and NaHtot respectively,and their deuteratedforms were preparedby aproceduredescribedin ourpreviouscommunication1.Preparation of thecomPlexes:(I) Bis(2-thioorotato)(diaquo)cobalt(II) - A solutionof I'Z g (,.....,5mmoles)of CoCl2.6H20in 30ml waterwasaddedto a solu-tion of 1·9g (,.....,10mmoles)of AmHtot in 100mlwater. The mixturewas refluxedfor Z hr whena greyprecipitatewasformed. It wascentrifugedand washedrepeatedlywith warm water.The deuteratedcomplexwas preparedby anidenticalprocedureexceptthat Dp and sodiumsalt of the ligandwereusedin the placeof H20and AmHtot.(II) (Z-Thioorotato)(ammine)(triaquo)cobalt(II)-A solutionof 0·6g (,.....,2mmoles)of CO(NOa)2·6H20.Present address:Lecturer,Departmentof Chemistry,GovernmentCollegeof Engineering& Technology,Raipur.tTo whomall correspondenceshouldbe addressed.in ZOml waterwas addedto a solutionof 0·4 g(,.....,2mmoles)of the ligand(H2tot) in excessof dil.ammonia(30 ml). After concentratingthe mixedsolutionto nearlyone-fourthof its volume,excessot acetonewas added,when a dark brownpreci-pitate was formedwhich was centrifuged,redis-solvedin theminimumquantityof waterandrepre-cipitatedby acetone.Thecomplexwascentrifugedand washedwith a little water.(III) (2-Thioorotato)(pyridine)(triaquo)cobalt(II) -A solutionof 0·4g (,.....,1·5mmoles)of CO(NOa)2.6H20in 20 ml pyridinewasaddedto a solutionof 0·2g(",,1mmole)of the ligand(H2tot)in 20mlpyridinecontainingapproximately0·2ml water. On mixingthetwo solutions,an intensepink colourdeveloped.The solution was slowly evaporatedwhen pinkcolouredcrystalswereformed. Thesecrystalswereseparatedby centrifugationand washed withacetone.(IV) (Z-Thioorotato)(diPyridine)(diaquo)cobalt(II)-The methodof preparationof this complexwassimilarto that describedin (III), exceptthat themetalsalt andthe ligandweremixedin 1:1 ratio,pyridinewasusedin largeexcess,andthecontentswereboiled for 15 min and then digestedon awater-bathfor 4 hr. A light brown complexwasobtained.(V) (2-Thioorotato)(aniline) (aquo) cobalt(lI) - Asolutionof 0·5 g (,.....,2mmoles)of CoCI2.6H20in20 ml waterwasaddedto a warmsolutionof 0·7g(,.....,4mmoles)of theligand(H2tot)inasolventmixturecontaininganiline (50 ml) and ethanol (10 ml).The resultingsolution was evaporatednearly todrynessonawater-bath.Theblackresidueobtainedwaswashedwitha largequantityof absoluteethanolfollowedby 50% ethanol.(VI) (2-Thioorotato)(methylaniline)(aquo)cobalt(II)-Thepreparationof this complexwassimilarto thatdescribedin (V) exceptthat methylanilinewasusedin the placeof aniline. The complexwas blackin colour.(VII) Bis(2-thioorotato) (aminopyridine) (diaquo)cobalt(lI) - A solutionof 1·4 g (,.....,6mmoles)ofCoCI2.6H20in 50ml waterwasmixedwith anothersolutionof 2·1g (,.....,12mmoles)of theligand(H2tct)and2·3g (,.....,24mmoles)of aminopyridinein 180mlof 80%ethanol. Theresultingsolutionwasdigested537INDIAN J. CHEM., VOL. lSA, JUNE 1977for 2hr on a water-bathand then left overnightwhen a brownishblack precipitatewas formed.It wa centrifugedand washedwith ethanol.(VII) (2-Thioorotato) (triethylamine) (tetraaquo)-cobalt(I) - A solutionof 2·4 g (",10mmoles)ofCoC12.H20 in 50 ml waterwas addedto a warmsolutin of 1·7g (",10 mmoles)of theligand(H2tot)in a lvent mixturecontaining100ml ethylamineand 2 ml of ethanol. An intensered-browncolourof t solution developed.It was evaporatednearl to drvnesson a water-bath. A few ml ofwaterwereaddedto theresidueandit waswarmedto ge a clear solution. To this solution,excessof actone was addedwhena dark-browncomplexpreci 'tatedout. It wascentrifugedoutandwashedwith cetone.(IX) . (2-Thioorotato)(quinoline) (aquo) cobalt(II)-A soltion of 1·9g (",8 mmoles)ofCoC12·6H20in30ml waterwasaddedto a warmsolutionof 1·4g(",8 moles)of the ligand in a solventmixturecontaning quinoline(50 ml) and ethanol(35 ml).The r suItingsolutionwasdigestedon a water-bathfor 2 hr when a black precipitateappeared.Itwas lowedto standovernight. Excessof ethanolwasa dedto themixtureandtheresidueseparatedby ce trifugationandwashedwithexcessof ethanol.All the complexesweredried at 110°.emPlexes of iron, rhodium, platinum and palla-dium (X) Bis(2-thioorotato)(tetraaquo)iron(II);(XI) bis(2-thioorotato) (diaquo) rhodium(III);(XII) bis(2-thioorotato)(diaquo)platinum(II) ; and(XIII tris(2-thiorotato)(dichloro) (tetraaquo)di-palla ium(IV)werepreparedby mixingin stoichio-metri ratiosolutionof metalion [Fe(S04)(NH4)2S04'6H20, Na2PtCl6 and K2PdC16in water and RhCls.xH20 in ethanol] and an aqueoussolution ofNH4Htot. The reactionmixturewas digestedfor2 hr in eachcase. The complexesof Fe(II) andPt(IV) were centrifugedout while the solublecomplexesof Rh(III) and Pd(IV) wereevaporatedto dryness. All the complexesweredriedat 110°.Preparationof deuteratedcomplexes-The deuterat-ed formsof the complexes(XI), (XII) and (XIII)werepreparedby refluxing0·2 g of the respectivecomplexin 20 ml D20 for about 2 hI. D20 wasremovedby evaporatingthe solution to dryness.The complexeswere finally dried at 110°.Analyses- Sulphurin thecomplexeswasestimat-ed by fusinga knownamountof the compoundina mixtureof KNOa and KOH (1: 8, wjw) followedby extractionwith distilledwater,acidificationwithHNOa and estimationof sulphateion as BaSOl2.Analysesof Co, Fe, Pd, Pt andRh in therespectivecomplexeswere carried out by decomposingthecomplexesby aqua regia followedby evaporationto drvness,extractionwith water and estimationof m~talions by standardmethodsI2,14.Carbon,hydrogenandnitrogenwereanalysedby theMicro-analyticalSectionof the Indian Instituteof Techno-logy, KanpuI.Molecular weights of water soluble complexesweredeterminedby cryoscopicmethod.ResultsandDiscussionThe analyticaldata (Table 1) indicatethat themetalions, exceptPd(IV), form two typesof com-plexes: (a) ML2(H20X)(X)y and (b) ML(H20)a(X)b'Pd(IV) formscomplexof the type Pd2LaC12.4H20.TABLE 1- ANALYTICAL DATA AND MAGNETIC MOMENTS OF THE COMPLEXESComplexCalc. (Found), %I-teff(BM)CHNSMaN,OaS),(H,Oh27·52·312·814·6-4 4,9(27'5·3312'9),N,OaS) (NHa) (HPla*0 03,3'90'9 3·750 62" ) CsHsN) (HPla*33·1568,86 3 -(32'7, 72' ),OaS) , ,O),*42 3-27 5 442 94 04-42N203S) . ,N) )8,927(38'40" ,03 ) ( , ,(H,O ,9,44 169 1603 2(CsH.N ) (H2O),'5134-4, 5 15 ) (H2O).*760 21P3S , ) ( 2 )44 ,531··" ) (H2O ,61 5 363-25·0Diamagnetic(24-47Pd2(QH P " l,(H,O . t20'89 7 do20'·, " . H o)2-3 6*Molecular weight determination showed monomeric nature of the complex.tCl was also estimated.-I 538111111PANDEY et al.: COMPLEXES OF 2-THIOOROTIC ACID- -------------------------------.. ---- 1IMagnetic MomentThe complexesof Rh(III), Pd(IV), and Pt(IV)are diamagneticas expectedfor octahedralcom-plexesof thesemetalionsts. The magneticmomentof Fe(II) complex(determinedby the Gouymethod)is 5·2 BM. This valueis well within the accept-able rangefor octahedralFe(II) complexest6•Themagneticmomentsof the presentCo(II) complexeslie in the range 3·75-4·9BM. While the valuesaround 4·9 BM indicate octahedralcoordination,valuesaround3·75BM. maybe due to tetrahedralfield or tetragonaldistortion of the octahedralgeometeryts-19.TetrahedralCo(II) complexeshouldnot show magnetic momentsbelow 3,87 BM,therefore,tetragonallydistortedoctahedralstructuresare assignedto the presentcomplexes.This isin conformitywith the resultsof electronicspectraalso.ElectronicSpectra*Cobalt comPlexes- In the electronicspectraofhigh-spinoctahedralcomplexesof Co(II), oneshouldexpectthreebandscorrespondingto the transitions4Tlr4T2g; 4Ttr4A2g and 4Ttr4Ttg(P). In tetra-hedral complexes,three bands correspondingtothe transitions 4A2g~4T2g, 4A2r4Tlg(F), and4A2r4Tlg(P) shouldappear. One can distinguishbetweenthe two geometrieson the basisof (i) re-latively largervalue of the extinctioncoefficient,(ii) presenceof a band in the near infraredregion(5000-8000)andthe absenceof any d-d' transitionbandaround25000in the-spectraof the tetrahe-dralcomplexes.In octahedralcomplexes,the ratioof the v2(4Tlg(F)-+4A~)and Vl(4Ttg-+4T2g)shouldlie in the range2·1-2·2(ref.20).The electronicspectralband positionsand theirrespectiveassignmentsalong with the values ofcrystal field parametersof Co(II) complexesaregivenin Table 2. Using thesevaluesof Dq andB, thepositionsof thesecondband(v2) werecalculat-ed in every case. These values correspondwellwith those found experimentally.The ratios ofV2 andVI calculatedfor eachcomplexlie_in therange2·1-2·2. The extinctioncoefficientsof the bandslie below100. The valuesof 10Dq arewellwithinthe rangefound for the other Co(II) complexes,and approximatelysimilarto the valuesof 10 Dqfoundfor octahedralNi(II) complexeswith thesameligand20•All theseobservationsuggestoctahedralgeometryof the ligandsaroundCo(II) ion in thecomplexes.In somecasesthevaluesof B calculatedby assumingtetrahedralgeometrywere found tobemorethanthefreeionvalue(Bo=1120).Besides,no band was observedaround4000in any of thecobaltcomplexes.The valuesof ~for thecomplexeslie in therange0,8-0,95whicharesimilarto thosefoundfor Ni(II)complexeswith the sameligand1. This indicatesthebondingin thesecomplexesto bepredominantlyionicwhichoneshouldexpectin the caseof Co(II)TABLE 2- ELECTRONICBANDS,THEIR ASSIGNMENTSAND CRYSTALFIELD PARAMETERSComplexBandAssignmentDqB~V2/VIposition(em-I)(em-I)(em-I)Co(Htot)2(H.O).VI9030'TIg(F)-.-'T ~V. (exp.)19085- 4T~(F) '-'A ~101410900'95·1V2(calc.)0Va2410} (F) . 4T(P)Co(Htot).(ampy)(H.O).524}g T.g22049 -'A.g10966· 4.4' ( )-.-' }gtot)(ani)(H2O)v,71,g(F)-.-'T.gv1362, . 209710,85'v2 , ( )NHa)(H.O)a(6)}v. ( .)25 (5)}g(F) .-'A88 46)( ) . 'T,qu n}8 5' , . .g863 948552- 5. ( l .)810 , (P)( te .O),70 8, .-',2· 6.52Py).( . .1')7I ' o8072 8 3 T ( )Fe H.O),1· . -~·Eg59000 (shoulder)The values in parenthesesare the extinction coefficientvalues calculatedin the caseof solublecomplexonly.*Band positions in em-I. 539INDIAN J. CHEM., VOL. 15A,JUNE 1977metal' on (A -class of metal ion) which preferentiallybinds with oxygen and nitrogen donor atoms.Iro comPlex-- In octahedral high-spin Fe(II)compl x one should expect a band (5T2g---'75Eg)aroun 100DO,while in tetrahedral complex a band(5Eg T2g) shouldappeararound4000. The presenceof a and at 10500in the present iron complexindica es the octahedral geometry of the complexwhich is also in conformity with the magneticmome t data. The value of 10 Dq calculated fromthe sition of this band is similar to the onesobtai ed for Ni(II) and Co(II) complexeswith thesame igand.Th band at 10500appearedto be split into twocomp nents. This may be explained either by theprese ce of low ligand field component or by theJohn- eller distortion.Ge . rally, Fe(II) complexesexhibit M---'7L charge-transf r bands20• A very intense band around20,00 in the spectrum of the presentcomplex maybe du to charge-transfer.Pd( V), Pt(IV) and Rh(III) comPlexes- In thespect of thesecomplexes,only very intensebandsappea' in the visible region. These may be assign-ed to charge-transferbands which will mask theweak d-d transitions of the complexes. So, nodefini e assignments of the geometries could bemade on the basis of the spectral data. However,the damagnetism of the complexes indicate theiroctah dral geometrieswhich conform to the pre-ferred geometrieswhich these metal ions generallytake their complexes.Infrar d SpectraTh IR spectra of the ligand, its sodium andamm ium salts have been discussed earlier1. Ithas b en indicated that the predominant tautomericform f the ligand present in the solid state is thethion form.The ligand molecule contains -··COOH, -NH-C=S,' and -NH-C=O groups and shifts in thespect of the complexesshould be expectedin thepositi ns of the bands due to these groups. Itis rea'onable to expect similar shifts in the bandpositi ns of complexes having the srrme bondingpatte The complexes have been, therefore,classi ed into the following groups based on thedirect ons of the shifts in the major infrared bandpositi ns. The infrared spectra of their deuteratedforms have also been studied in order to confirmthe b nd assignments.CoPlexes of the type ML2(H20)x(X)y [whereM =Co(II , Fe(II)J -. The shifts in the band positionsin th infrared spectraof CoL2(H20)2' FeL2(H20)4'and oL2(ampy)(H20)2 were similar to those ofNiL2( 20)2' the spectrum of which has beendiscus-sed i our earlier communication1. In the case ofCoL2( mpy)(H20)2' bands due to aminopyridinewere Iso present besidesthose due to CoL2(H20)2moiet. It is, therefore,assumedthat the bondingsites i these complexesare carbonyl and carboxyloxyge atoms besides aminopyridine and watermolec les.Can lexesof thetype CoL(H20)a (X)b- The shiftsof th band positions in these complexes were540similar to those in the spectra of NiL(H20)a(Xhand Cu(II) complexes!. It is, therefore, assumedthat the bonding sites are carboxylate oxygen,ring nitrogen of the NH group (after deprotonation)and amine and water molecule.Platinum and palladium comPlexes- The bandsin the spectra of the platinum and palladiumcomplexes were rather broad which may be dueto their polymeric nature. However, the followingshifts were observedin someof the band positions:(i) The position of the band at 1740due to carboxy-late COO shifted to 1700. (ii) The positions of thebands at 1680,680and 620did not changesuggest-ing no interaction with carbonyl or amide group.(iii) The positions of the thioamide bands at 1030and 945 shifted to 1000 and 900 respectively.(iv) The intensities of the '1N-H and '1N-D wererelatively smaller than those in the ligand anddeuterated ligand respectively. In the spectrumof the complex,a very broad band at 3000appeared.The broadnessof the band may be due to hydrogenbonding. (v) Two new bands appeared around470 and 320. These have been assignedto '1M-Oand '1M-So (vi) The band at 1230shifted to 1270and another \veak band appeared at 1220.From the above shifts the bonding of the metalion through the oxygen of carboxylate group, nitro-gen of one of the N-H groups (after deprotonation)and thiocarbonyl sulphur atomshas beensuggested.RhodiumcomPlex,RhL2(H20)2 -' The IR spectrumof rhodium complex is similar to that of Pt(IV)complex except for the following differences:(i) The band positions due to 'I O-H, '1N-H and'1C-H at 3500, 3200 and 3160 respectively wereshifted on dl1terationto 2450, 3200,and 3160. Itappears that in this complex, only the water mole-cules are exchangedby D20 while the protons ofthe N-H and C-H are not exchanged. This isfurther confirmed by the fact that the positions ofthe bands due to aN-H, and 't"N-H at 1550, 1440,and 720 did not shift on deuteration while that ofaO-H of water molecule shifted to 1090.(ii) The bands due to '1C=S at 940 and 1020splitted into two bands each at 935 and 920 and1020and 1010respectively. It appears that thereare two types of C=S groups in the complex, onebonded to metal ion resulting in the lowering of(=S band positions and a non-bonded (=S, inwhich casethe positions of the bands will not shift.(iii) All the bands due to coordinated watermoleculesare present at 3500, 1600and 850.(iY) The shifts in bands due to N-H groups wererather confusing. Some bands were shifted towardshigher wave number side while the othersremainedunchanged. In order to keep the charge balance,one of the N-H groups of the ligand has to be de-protnated to coordinate with the metal ion andthus, it will complicate the spectrum.(v) Two new bands at 550 and 370 appearedinthe spectrum of the complex. These have beenassigned to '1M-O and '1M-S respectively.Hence the bonding through oxygenof carboxylategr~mpand N of oneof the N-H groups(deprotonated),thlOcarbonyl sulphur and two molecules of waterhas been proposed.PANDEY et al.: COMPLEXES OF 2-THIOOROTIC ACIDReferences1. PANDEY, G. 5., NIGAM,P. C. & AGARWALA,D., J. inorg.nucl. Chem. (in press).2. PANDEY, G. 5., NIGAM, P. C. & AGARWALA,D., IndianJ. Chem.,15 (1976).3. MOOR, H., Brit. Pat. 1193 (1970); Chem. Abstr., 73(1970),698525x.4. CHELBOVA,K y, GOLOVINSKI,E. & HADJIOLOV,A. A.,Biochem.Pharmac., 19 (10) (1970),2785.5. RENDINA, G., SARCIONE,E. J., LEE, O. J. & BARRETT,H. W., Proc. Soc. expoBioi. Med., 95 (1957),350.6. CHEMOFORMA,A. G., Fr. Pat. 1,569,124(1969); Chem.Abstr., 72 (1970),41973z.7. THOMASMURRAY, J., US Pat. 909,023(1973).8. SCHEIBITZ,M., KABBE, J. H., VON KONIG, A., GOETZE,J. & WEYDE, E., Ger. Pat. 2,013,423(1971).9. JOHNSON,T. B. & SCHROEDER,ELMER F., J. Am. chem.Soc., 53 (1931),1989.10. JOHNSON,T. B. & CRETCHAR,J. Am. chem.Soc., 37(1915),2144.11. JOHNSON,T. B. & SCHROEDER,ELMER F., J. Am. chem.Soc., 54 (1932),2941.12..TREADWELL,F. P. & HALL, W. T., Analytical chemistry,Vol. II (John Wiley, New York), 1958,77, 199.13. COTTON,F. A. & WILKINSON, G., Advancedinorganicchemistry (Interscience Publishers, London), 1972,1031.14. VOGEL, A. I., A text book of quantitativeinorganicanalysis (LongmansGreen, London). 1968, 389; 460;462; 511. .15. FIGGIS, B. N., Introductionto ligandfields (IntersciencePublishers,New York), 1966,248.16. COTTON, F. A. & WILKINSON, Advanced inorganicchemistry(IvtersciencePublishers,London), 1974,862.17. FIGGIS, B. N. & NYHOLM, R. 5., J. chem.Soc., (1954),12.18. SELWOOD,P. W., Magnetochemistry(IntersciencePub-lishers,London), 1956.19. NYHOLM, R. 5., Chem.Rev., 53 (1953),282.20. LEVER, A. P. B., Inorganic electronic spectroscopy(Elsevier, New York), 1968.1I

Complexing Behaviour of 2-Thioorotic Acid: Complexes of Co(II), Fe(II), Rh(III), Pd(IV) & Pt(IV)

http://nopr.niscair.res.in/bitstream/123456789/53123/1/IJCA%2015A%286%29%20537-541.pdf

Complexing Behaviour of 2-Thioorotic Acid: Complexes of Co(II), Fe(II), Rh(III), Pd(IV) & Pt(IV)

Abstract

Similar works

Full text

Available Versions

NOPR