Pradhan, B.

Rao, D. V. Ramana

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NOTESTABLE1 - ANALYTICALDATAOFTHECOMPLEXES'"Complex Colour Analysis (%). Found (calc.) log kl log k. log K v-«Metal N(BM)[Cu(C.H.02N)2(H2O)2J Blue 21·25 (21-49) 9·29 (9'47) 3·68 2·76 6·44 1·81[Ni(C.H.O.N)(OH)(H2O).J Green 24·00 (23-89) 5·52 (5'69) 3·00 3·30 3·10[Co(C.H402N)2(H2O)2J Blue 20·10 (20·25) 9·53 (9-62) 3·17 3·11 6·28 4·30[Fe(C.H.02N) (OH) (H2O)4J Pale 23·10 (22'99) 5·58 (5·76) 3·10 5·60 5·20[Hg(C.H.O.N) (OH)JgreenWhite 63-99 (63·56) 4·29 (4043) 6·88 6·88*Satisfactory C and H analyses were obtained.ethanol and dried in vacuo. The ferrous complexslowly changed to the ferric complex in air. Hencethe preparation was carried out under Nz atmosphere.The Fefl I) complex is stable for 4 hr after drying.Analysis for the metal. C. Hand N are given inTable 1.Stability constants (Table 1) were determined byBjerrum's" pH-metric method. Solutions of succini-mide (40 ml, 0·012SM) with and without metal ion(5·0 ml, O'OIM) were titrated against KOH (0'075M)at 200 ± Io. The ionic strength (fL) was maintainedconstant. at O'lM with KCI, KNOs' K2S04 andNaClO, In the case of Cu(ll). Co(II), Fe(ll) , Ni(II)and Hg(ll) complexes respectively. The accuracyof log K values (concentration constants) reported is+0,02.- The data in Table I indicate that Ni(ll), Hg(ll)and Fe(ll) form 1: 1 complexes while Cu(ll) andCo(ll) form 1: 2 complexes. The presence of poly-nuclear species can be neglected since the formationcurves (11, vs pA), determined from the ligand-metalratio of 5: 1 and 6: 1 are identical. For Fe(II)-succinimide complex, 11, values beyond 0·5 could notbe obtained due to the onset of hydrolysi.+, Thetit!ations were carried out in nitrogen atmosphereusmg freshly prepared FeS04.7HzO solution. Theerr?r in log K value was of the order of ± 0·1 logunits.The compositions of the complexes were furtherconfirmed by conductometric titration and chemicalanalysis. pK values as determined by potentio-metric titration of 40 ml succinimide (0·025M)against 0'084M KOH were found to be 9'45, 9·70,9·55 and 9·30 in KCI, KN03, KzS04 and NaCI04medium (fL=O'lM) respectively.Chemical analysis of the solid complexes is inaccordance with the formulae assigned to them.Their magnetic moment values are given in Table 1.While Hg(ll) complex is diamagnetic, Cu(ll), Ni(II),Co(ll) and Fe(ll) complexes are shown to contain1, 2, 3 and 4 unpaired electrons respectively. Thecomplexes are nonelectrolytes in nitrobenzene. Apartfrom other bands, their IR spectra show bands at1030 and 600 crrr? which may be assigned to co-ordinated hydroxo groups.References1. DAVIES,C. W. & NANCOLLAS,G. H., Nature, 165 (1950), 237.2. MALIK, W. U, SHARMA,C. L., JAIN, M. C. & ASHRAF,Y.,J. inorg. nucl, Chem., 33 (1971), 4333.3. MARTELL,A. E. & KALVIN, M., Chemistry of metal chelates(Prentice-Hall, New Jersey), 1959, 80.4. MANN,F. G. & WATSON,H. R, J. chem, Soc., (1958), 2772.Reaction of Bis-j-dfketonates of Zn(II) withThioureaB. PRADHAN& D. V. RAMANARAODepartrne.rt of Chemistry, Regional Engineering CollegeRourktlla 8Received 7 August 1975; accepted 4 October 1975The mixed Ilgand complexes of Zn(II) of the typeZn(p-dik).L (where L = thiourea and P-dik = acetyl-acetone, benzoylacetone or dibenzoylmethane) havebeen prepared as examples of 5-coordinated complexesof Zn(II) with a sulphur donor li~and. The Compoundshave been characterized on the basis of magnetic, con-ductance and spectral data.THE. best examples of 5-coordination for Zn2+,which has. a completely filled 3d non-bondingshell and WhICh usually forms four coordinatedt~trahedral compounds, ~re found among the ~-diketonate complexes having the formula Zn(~-dik.)H20. .A wide variety of base adducts of the typ:Zn(~-dlk.)zL have been reported where L is anitrogen donor ligand-+, In this note, some penta-coord~~ted J1!ixed ligand complexes of Zn(II)containing ~-dlketones and a sulphur donor ligandlike thiourea are reported..All the chemicals used were of Analar grade.Bis-acetylacetonato, benzoylacetonato and di-benzoylm~thanato Zinc(II) compounds are preparedby the hterature methods. Ethanolic solution ofthese compounds and thiourea in stoichiometricrat~o of .1: 1 were refluxed for 3-4 hr. On cooling,white micro-crystalline compounds which separatedout were filtered, washed with absolute ethanolfollowed by ether and dried in vacuo.Zn(ll) in the mixed complexes was estimateda~ ZnNH4J.>04.and sulphur as BaS04 after oxidizing!with bromine In carbon tetrachloride solution. Theconductance measurements were carried out inM /1000 nitrobenzene solutions using a Toshniwalco~ductivity bridge. Magnetic susceptibilities ofsO~Idsamples were determined at room temperatureUSIng the Guoy method. Characterization dataof the complexes are given in Table 1.The complexes have the composition [Zn(~-dik')2L]and are soluble in nitrobenzene and have low valuesof molar conductances « 1·0 mhos) indicating thenon electrolytic nature of the complexes. Theseare diamagnetic as expected for Zn(ll) ion witha completely filled 3d shell.535INDIAN J. CHEM., VOL. 14A, JULY 1976Complex ColourTABLE 1- CHARACTERIZATION DATA 01' Zn(II) CoMPLEXESm.p. Zn (%) S (%)(0C)Found Reqd Found Reqd170 19·20 19'24 9'61 9'43198 14·41 14'09 7'04 6'91210 11'32 11'12 5'70 5-45Zn(acac).LZn(bzacltLZn(bzbz}.LWhiteGreyWhiteH.acac = acetyl acetone; H.bzac = benzoyl acetone; Hvbzbz = dibenzoyl methane; L = thiourea.The ~-diketonates of Zn(II) exhibit v(O-H)band ",3490 em? in the IR spectra (nujol) dueto the presence of a coordinated water molecule.When the ~-diketonates are reacted with thiourea,water molecule gets replaced by thiourea and thisis shown in the IR spectra of the mixed complexesin which v(O-H) band disappeared and a banddue to v(C-S) appeared ",710 crrr+, In thioureathe v(C-S) appears" 740 cm-l. In the mixedcomplexes, this band is shifted to lower frequency(",710 cm+) indicating definite metal-sulphurbonding in the adducts. Further, the resonatingring system present in the ~-diketonates gets dis-turbed by the introduction of thiourea ligand,in place of water molecule. This results in shiftingof v(C-C) and v(C-O) after thiourea has beenintroduced. The v(C-C) observed at 1600 crrr+in ~-diketonates was shifted to a higher frequency(ranging between 1610 cm-l and 1620 crrr+) inthiourea complexes. Hence, thiourea is definitelyborided to the zinc ion. The present complexesprovide examples of penta-coordinated complexesof Zn(II) with sulphur as one of the donor atoms.References1. MOHAPATRA, B. K. & RAMANA RAO, D. V., Z. anorg . allg.cu«, 372 (1970); 332.2. GRADDON, D. P. & WEEDEN, D. G., Aust. J. Chem., 17(1964), 607; 1052.3. GRADDON, D. P. & WEEDEN, D. G., Aust. J. Chem., 16(1963), 980.4. HAIGH, J. M., SLABBERT, N. r. & THORNTON, D. A., J.inorg, nucl, Chem., 32 (1970), 3635.S. VOGEL, A. I., A text book of quantitative inorganic analysis(Longmans, London), 1961. 467.6. SWAMINATHAN, K. & IRVING, H. M. N. H., J. lnorg, nucl.Chem.,26 (1964), 1291.Magnetic & Spectral Studies on Ni(II) & Cu(II)Complexes of N-(Salicylidene)phenylhydrazineA. N. SUNDER RAM & C. P. PRABHAKARANDepartment of Chemistry, University of KeralaTrivandrum 695001Received 9 September 1975; accepted 29 October 1975Ni(I1) and Cu(I1) form 1:1 complexes with theSchUl base (LH) derived from salicylaldehyde andphenylhydrazine. The physico-chemical data indicatea square-planar stereochemistry for the Ni(II) com-plex and a tetrahedral stereochemistry for the Cu(II)complex. A pyridine adduct of the nickel complex,NiL.PYI has also been isolated. The pyridine adductis paramagnetic and octahedral.536N-(SALICYLIDENE)PHENYLHYDRAZINE(LH) has been recommended as a gravimetricreagent for transition metals-. However, complexesof this ligand have not been investigated so far.We report here the preparation of Ni(II) and Cu(II)complexes of SPH and their characterization on thebasis of magnetic moment, conductance and elec-tronic and IR spectral data. A pyridine adductof the Ni(II) complex has also been prepared.The chemicals employed were of reagent quality.The solvents were purified by standard methodss.Preparation of the complexes - The complexeswere prepared by adding an aqueous solution ofthe metal chloride to an ethanolic solution of theSchiff base, LH, in an ammoniacal medium. Thebrown and the greenish-yellow precipitates obtainedin the case of Cu(II) and Ni(II) respectively werefiltered, washed with ethanol and ether and driedtn vacuo.The pyridine adduct of the Ni(II) complex wasprepared by refluxing an ethanolic solution of thecomplex with pyridine. The orange-yellow crystalsseparated were washed with ether and dried invacuo. The complexes were found to be insolublein water, but soluble in almost aJl organic solvents.Copper was estimated iodometrically after decom-posing the complex with nitric acid, while nickel wasestimated gravimetrically as dimethyl glyoximate.The analytical data of the Cu(II) and Ni(II)complexes correspond to the compositions CUL2and NiL2 while the pyridine adduct has the com-position NiL2PY2'The molar conductance values of less than unityfor 10-3M solutions in nitrobenzene show the non-conducting nature of the complexes.The IR spectrum (KBr) of the free ligand, whichhas three potential coordinating sites, exhibitsa sharp medium intensity band at 3300 crrr? whichcan be assined to '.IN-H. In the spectra of thecomplexes, this band does not show any shift indi-cating that coordination does not occur throughthe N-H group. A broad medium-intensity bandobserved around 2900 cm-1 in the ligand due tohydr?gen bonded -OH disappears on complexationshowing that hydrogen of the OH group is replacedby the metal ion. A medium intensity band at1530 em+ assigned to vC=N of a conjugated ringsystem= in the ligand is shifted to 1540 cm-l in itscomplexes showing that nitrogen of the C=N groupis involved in complexation. Thus, the IR dataindicate that the potentially tridentate ligand actsonly as a monovalent bidentate ligand making useof the oxygen of the -OH group and nitrogen ofthe azomethine group in coordination.

Reaction of Bis-β-diketonates of Zn(II) with Thiourea

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Reaction of Bis-β-diketonates of Zn(II) with Thiourea

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