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1. ANAND, S. P., MULTANI, R K. & JAIN, B. D., Curro Sci.,17 (1968),487; J. organometal. Cbem., 17 (1969), 423.

2. FRITZ, H. P., Adv. organomet. Chem., 1 (1964), 279.3. SCHARF, G. W. & BROWN, R. K, Can. J. cu«, 38

(1960), 697.4. BELLAMY, L. J., The infrared spectra of complex mole-

cules (Methuen, London), 1958, 15.5. RAO, C. N. R, Chemical applications of infrared spectro-

scopy (Academic Press, New York), 1963, 201.6. VRATNY, F., RAO, C. N. R & DILLING, M., Analyt. cu«,

33 (1961), 1455.7. DAVIES, M. & JONES, R L., J. chem: Soc., (1954), 120.g. KHARlTONOV, Yu. YA., BURLAEV, Yu. A. & KUZAETSOVA,

N .. \., Zh. neorg, Khim., (1966), 11.9. NAKANISHI, Koj r , Infrared absorption spectroscopy,

Practical (Nankodo, Japan), 1962, 30.

Complexes of Co(I1), Ni(I1), Cu(I1), Zn(I1) &Cd(II) with Dithiodipropionic Acid

K. C. TEWARI, (Miss) A. VARSHNEY, R. C. GAUR & J. CHANDRA

Department of Chemistry, Aligarh Muslim UniversityAligarh 202001

Received 20 November 1976; accepted 13 June 1977

Complexes of Co(II), Ni(II), Cu(II) , Zn(II) andCd(U) with dithiodipropionic acid (DTDPA) havebeen prepared and characterized on the basis ofanalytical, magnetic moment, conductance, electronicand IR spectral data. The complexes are thermallystable and nonelectrolytic in dimethyl sulphoxide.IR evidence shows that coordination takes placethrough the sulphur and carboxylate oxygen atomsand the complexes have octahedral structures.

THE chemistry of metal complexes of thiopoly-carboxylic acids>" has been well studied over

the past few years. Many metal complexes ofethylene dithiodiacetic acid (CH2-S-CH2-COOH)2have been studied in detail--". We report here thepreparation and characterization of Co(II), Ni(II),Cu(lI) , Zn(II) and Cd(Il) complexes of isomericdithiodipropionic acid (DTDPA) (S-CH2-CH2-COOH)2'

Dithiodipropionic acid (Evans Chemetics, NewYork) of 99'5% purity was used without furtherpurification.

For the preparation of complexes, aqueous solutionof metal chloride (50 ml, 0'2M) was added to anequimolar solution of DTDPA (150 ml) in ethanol.A few drops of concentrated NaOH were added toadjust the PH of the solution in the range 4-5 andthe resulting mixture was then refluxed for 4 hrover a steam-bath. On cooling, a solid separatedwhich was filtered, washed with water and ethanoland dried at 60°.

All the prepared complexes were insoluble inwater but sliGhtly soluble in dimethyl sulphoxideand nitrobenzene.

Co(II)~DTDPA complex was a light-pink solidwhich decomposed at 278° [Found: Co, 19°58;C,23·82; H, 3·79; S, 21·08. Co(CSHSS20 •.).2H:20requires Co, 19'45; C, 23·76; H, 3·98; S, 21·14%J.

Ni(U)- DTDPA complex was a green solid whichdecomposed at 232° [Found: Ni, 17·31; C, 21·34;

NOTES

H, 4·85; S, 18·72. Ni(C6HsS!04).4H20 requires Ni,17·36; C, 21·25; H, 4'75; S, 18·88%]. Thermo-gravimetric analysis showed loss oi two moles ofwater at 140°.

Cu(ll)-DTDPA complex was a bluish-green solidwhich decomposed at 2200 [Found: Cu, 20'74; C,20·72; H, 3·84; S,23·28. Cu(C6HsS204).2H20 requiresCu, 20'64; C, 20'83; H, 3·92; S, 23·41%].

Zn(ll)-DTDPA complex was a white solid whichdecomposed at 2600 [Found: Zn, 23·73; C, 26'30;H, 2·88; S, 23'36. Zn(CSHSS204) requires Zn,23·89; C, 26·33; H, 2·94; S, 23·43%J.

Cd(ll)-DTDPA complex was a white solid whichdecomposed at 237° [Found: Cd, 35·16; C, 22·50;H, 2'66; S, 19·88. Cd{CsHsS204) requires Cd, 35·05;C, 22'48, H, 2'48; S, 19·99%].

The specific conductances of the complexes weredetermined in saturated solutions of dimethyl sul-phoxide using a Philips conductivity bridge modelPR-9500. The magnetic measurements were madeon a Gouy balance and the diamagnetic correctionsapplied using Pascal's constants". The electronic(diffusion reflectance) spectra were taken on aZeiss PMQ II spectrophotometer from the samplediluted with magnesium carbonate and spread ona filter paper. The IR spectra were obtained innujol on a Perkin-Elmer 621 grating spectrophoto-meter.

The observed decomposition temperatures (303-304·5°K) and specific conductance values (5·0-6·4X 10-6) in dimethyl sulphoxide, indicate that thecomplexes are thermally quite stable and nonelec-trolytic in nature.

Co(II) complex - The observed magnetic momentof 4·93 BM at 304·5°K is usual and suggests thatthe complex is octahedral''.

The electronic spectrum of the complex showsthree hands at 8·3, 17·6 and 20·8 kK which may beinterpreted in terms of the transitions 4T1g(F)-+4T2g(1/1),4J'lg(F)-+4 A2g(1/2) and 4TIg(F)-+4TIg(P)(Va) res-pectively in an octahedral field. The ligand fieldparameters were calculated by the use of semi-empirical equations". The calculated value (0·934)of ~, Racah's parameter, relative to the gaseousion value, indicates a low degree of covalency andthe term separation, E(4P)-E(4F), of 13525 crrr-corresponds to about 94% of the free-ion valuet".The value of effective spin-orbit coupling constant,A (-153 crrr+) as calculated from Dq and B valuescorresponds to 86% of the free-ion value? (-178crrr+).

Ni(II) comple» - The observed magnetic momentvalue of 3·35 BM at 303·5°K is consistent with thegenerally accepted values in the range 3·20-3.40BM for high spin octahedral complexes6,8,ll. Theincrease in magnetic moment from the spin-onlyvalue could be due to some "mixing in" of upperstates via spin-orbit coupling>.

The electronic spectrum of the Ni{U) complexshows bands at 8·5, 14·5 and 25·0 kK which maybe due to the transitions 3A2g(F)-+3T2g(Vl), -+3T1g-(v2) and -+3T1,(P) (1/3) respectively in an octahedralfield. These bands are similar to those observedin the case of aquo Ni(ll) ionlS, [Ni(H20)6]2+. Theligand field splitting energy, 10 Dq, was taken as

913

INDIAN J. CHEM., VOL. 15A, OCTOBER 1977

equal to the energy of the first transition (VI) andthe Racah parameter, B, was calculated from theenergies of (VI), (',12)and (va) bands using the diagonalsum rule, 15B = ',12+',13-3',11' The observed separa-tion 10·50 kK, of (',12)and (va) bands compared withthe calculated value of 10·73 kK14, on the basis ofoctahedral symmetry, supports the octahedral natureof the complex. The value of ~ (0'896) indicatesa low degree of covalency and, (F-P), term separa-tion of 14000 em"! corresponds to about 88% offree-ion value. The calculated value of A (-276cm-) corresponds to 85% of the free-ion value (-324cm"). The nephelauxetic effect seems to be moreeffective for Co(II) than Ni(II).

Cu(II) complex - Magnetic susceptibility is not ofmuch use in deciding on the stereochemistry of cop-per complexes-+?". The observed magnetic momentof 1·93 BM at 303°K excludes strong spin-spinpairing but does not exclude a polymeric structure.The electronic spectrum of the Cu(II)-DTDPA

complex exhibits on,e broad asymmetric absorptionat 14·10 kK ascribed to the transition 2Eg-2T2g, ofthe octahedral Cu(II) ion-". The broadening maybe due to John-Teller effect, since the state 2Eg issusceptible to John-Teller distortion.

Zn(II) and Cd (II) complexes - The complexesare white crystalline solids and, as expected, arediamagnetic. The electronic spectra in, the UVregion exhibits an intense charge-transfer band at39·3 kK for Zn(II) and 40·0 kK for Cd(U) complexcompared to a band at 37·0 kK in the ligand.The IR spectrum of the ligand shows vS-S and

vC-S bands at 490 and 720 crrr ' which are loweredby 20-50 and 10-50 cm! respectively in the spectraot the complexes. The appearance of a new vM-Sband (310-330 crnt) on complexation and the shiftof vC-S and vS-S bands of the ligand to lower wavenumbers, indicate coordination through the sulphuratom. The increased affinity of zinc and cadmiumtowards sulphur in D1;DPA as compared to theisomeric ethylene dithiodiacetic acid! could be,attributed to the reduced steric hindrance and in-creased polarizability of the sulphur containingligand4,20. The presence of vCOO as in the range1520-1680 crrr+, as well as the separation (80-240cm+) of the anti symmetric and symmetric vCOOvibrations are consistent with the chelating carboxylgroups. Furthermore, the -OH deformation bandat 815 em"! in the ligand disappears on com-plexation indicating the ionization of the car-boxylic group. It is, therefore, concluded thatcoordination takes place through both sulphurand carboxylate groups. The Co(II) , Ni(II) andCu(II) complexes show a broad band in the region3150-3200 cm-I due to vOH of water molecules. Thetwo water molecules are not removed even on heatingto 100° indicating coordinated nature of water.However, a loss corresponding to two water mole-cules occurs at 140° in Ni(II) complex.ThankS are due to MIS Evans Chernetics Inc.,

New York, for a gift sample of dithiodipropionicacid and to Prof. W. Rahman, Head, ChemistryDepartment, for providing research facilities. Threeof us (A.V., RC.G. and J.C.) are grateful to theCSIR, New Delhi, for financial assistance.

914

References

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2. PETRAS, P. & PODLAHA, J., Lnorg, chim. Acta, 6 (1972),253.

3. JOEL, c., JACQUES, N. & GABRILE, T., C.R. Acad. Sci.,Ser. C, 275 (1972), 191.

4. PROCHAZKOWA, 0., PODLAHOVA, J. & PODLAHA, J.,Colln Czech. chem. Commun., 38 (1973), 1120, 1128.

5. PETRAS, P., PODLAlj:OVA, J. & PODLARA, J., CollnCzech. chem. Commun., 38 (1973), 3221.

6. KUMAR, A., JAIN, S. & TIWARI, S. K., J. inorg. nucl.Chern., 37 (1975), 2439.

7. FIGGIS, B. N. & LEWIS, J., Modern coordination chemis-try, edited by J. Lewis & R. G. Wilkins (Interscience,New York), 1967, 403.

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10. OWEN, J., Proc. R. Soc., London, 227 (1955), 183.11. NYHOLM, R. S., Chem. Rev., 53 (1953). 263.12. LEVER, A. B. P. & NELSON, S. M., J. chem. Soc., (1966),

A859.13. JORGENSON, C. K., Adv. client. Phys., 5 (1963), 33.14. BOSTRUP, O. & JORGENSON, c. K., Acta che m. scand.,

11 (1957), 1223.15. COTTON, F. A. & WILKINSON, G., Advanced inorganic

chemistry, 2nd ed. (Interscience, New York), 1966,902.

16. FIGGIS, B. N., Nature. 182 (1958), 1568.17. K.no, M., JONASSEN, H. B. & FANNING, J. C., Chem.

Rev., 46 (1964), 99.,18. KISHITA, T., KUBO S. & INOUE, M., Nippon Kagaku

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a- Nitroso-~-naphthol & ~-Nitroso-u-naphtbolDerivatives of Manganese(III) Acetate

S. SARASUKUTTY, A. N. SUNDER RAM' & c. P. PRABHAKARAN

Department of Chemistry, University of KeralaTrivandrum 1

Received 11 November 1976; accepted 19 April 1977

Mn(III) complexes of the type MnL2Ac (whereL = u-nttroso-Bvnaphthoj or !J-nitroso-Q-naphthol andAc = CH3COO) have been prepared and their electri-cal conductance, magnetic properties, thermal beha-viour and electronic and infrared spectra studied.The complexes are non-electrolytes and show sub-normal rnagnettc moments. The IR spectra suggestthat oxygen and nitrogen atoms of the Ilgand mole-cules act as the coordination sites. Electronic spectraindicate a distorted octahedral confrgur-ation aroundthe central metal ion.

METAL complexes of «-nitroso-Bcnaphthol and~-nitroso-(X-naphthol have received considerable

at tent ion! because the ligands are capable ofexisting in quinone-oxime and naphthol forms. Themetal-ligand bond formation can occur in a varietyof ways. Most of the work reported so far on themetal complexes of the two Iigands is based on

*Present address: Department of Chemistry, Universityof Florida, Gainesville 32611, USA.