2
INDIAN J. CHEM.; VOL. 20A, FEBRUARY 1981 been found to be 1.75 as compared to 2.1 reported by Hardwick and Robertson'" at 15°~ Activation parameters - From the effect of tem- perature on the rate of reaction, various activation parameters have been calculated with the help of Arrhenius plot. They are ,6,Et = 10.67 (± 0.2) k cal mol:", A (frequency factor) = 6.63 X 10 18 sec- i and ,6,St = 27.65 e.u. The activation energy of the reaction tallies with that reported by Tripathy and Prasad" in the case of reaction in ~S04 medium indicating identical situation in respect of bond fission (probably C---C bond fission). The high positive value of activation entropy is consistent with the absence of complexformation in the transition state which is the case in ~S04 medium where ,6,St = -14.22 e.u. The transition state in the present case is closer to the products obtained during slow decarboxylation step. One of us (S.P.) is grateful to the UGC; New Delhi for the award of a teacher fellowship. References 1. PANIGRAHI, G. P. & MISRO, K. PRAFULLA,' Indian J. Chem., 14 (1976), 579. 2. 'TRIPA.1'HY, S. N. & PRASAD,R. K., Unpublished data. 3. PRASAD, S. & PRASAD, R. K., Indian J. Chem., 17A (1979), 491. 4. DUKE, F. R. & FORIST, A. A., J.Am. chem. Soc., 71 (1949), 2790. 5. SHORTER, J. & H!NSHELWooD, C. N., J. chem. Soc., ( 1950), 3277. 6. SHORTER, J., J. chem. Soc., (1950), 3425. 7. WYLIE, A. W., J. chem. Soc., (1951), 1474. 8. SHORTER, J., J. chem. Soc., (1962), 1868. 9. YOUNG,L. B. & 'fRAHA,NOVSKY, W. S., J. Am. chem. Soc., 91 (1969), 5060. 10. SINGH, BHARAT, RICHARDS, KM. 'MEENAKSID,SHUKLA., ~(1~~6)~~79~ KRlsHNA, BAL, J. Indian chem. ,Soc., 11. BANARn, KALYAN, K., J. Indian chem. Soc., 52 (1975), 573. 12. SINGH, BHA.RAT, RICHARDS, KM. MEENAKSHI,SHUKLA, RN KlsHOR & KRlsHNA, BAL, J. Indian chem. Soc., 54 (1977), 378. 13. MATHUR,D. L. & BAKORE, G. V., Bull. chem. Soc. Japan, 44 (1977), 2600. . 14. SANKHLA, PREMS. & MEHROTRA, RN N., Indian J. Chem., 10 (1972), 175. 15. BALASUBRAMANlAN, T. R. & VENKATSUBRAMA.NIAN, N., Indian J. Chem., 9 (1971), 36. -: 16. VASUDEVAN,R. & MATHAI, 1. M., Indian J. Chem., 10 . (1972), 175. 17. BALASUBRAMANlAN, T. R. & VENKATSUBRAMANlAN, N., Indian J. Chem., 9 (1971), 1243. 18. RANGASWAMY, M. & SANTAPPA,M. S., Indian J. Chem., 7 (1969), 473. 19. FEIGL, FRITZ., Spot tests in organic analysis (Elsevier Publishing Company, N. Y.), 1960, 368. 20. HARDWICK, T. J. & ROBERTSON,E., Can. J. Chem., 29 (1951), 818. 21. SHERILL,M. S., KING, C. B. & SPOONER,R. C., J. Am. chem. Soc., 65 (1943), 170. 22. DUKE, F. R. & PARACHEN, R. F., J. Am. chem. Soc., 78 (1956), 150. 23. ARDON, M., J. chem. Soc., (1957), 1811. 24. KING, E. L. & PANDOW, M. L., J. Am. chem. Soc., 74 (1952), 1966. 25. WELLS,C. F. & KORITSYA.N, L. V., J. chem. Soc., (1969), 2930. t184 Dicarboxylato Chelates of Bis( cyclopentadienyJ)- & Bis(indenyJ)-titanium(IV) R. S. ARORA,S. C. HARI, M. S. BHALLA & R. K. MULTANI* Department of Chemistry, _University of Delhi, Delhi 110007 Received 4 February 1980; accepted 30 June 1980 A number of dicarboxylato chelates of bis(cydopentadienyl)- titanium(lV) and bis(indenyl)titanium(IV) have been prepared. These complexes have been characterised on the basis of molecular weight, IR spectra and analytical data. The nature of the metal carboxylate group linkage is also discussed. IN continuation of our work on the nitro and thiocarboxylato+" derivatives of (C s H s )zTiCI 2 (I) and (C9H7);:TiCl 2 (II), we report here the pre- paration and characterisation of dicarboxylato chelates derived from (I) and (II). The reaction is represented by the general Eq. (I) : (It-D)2TiCI2 + Na 2 (XX).----7(lt-D)zTi(XX) + 2NaCI .. (1) where D=cycIopentadienyl or indenyl group and XX = the bidentate ligand like oxalate, malonate succinate, tartarate or phthalate. ' AR grade chemicals were used. All reactions were carried under strictly dry conditions. Titanium was estimated as oxinate. Carbon and hydrogen were estimated by microanalytical methods. The IR spectra of these compounds were recorded in KBr on a Perkin Elmer spectracord Model-137 spectrophotometer. The various complexes were prepared by refluxing bistcyclopentadienyl)- or bis(indenyl)-titanium(IV) dichloride and sodium salts of various dicarboxylic acids in equimolar ratios in THF, at 60-70° for 6-10 hr. The resulting -solution was filtered and the fil- trate evaporated under reduced pressure. The re- sidue on repeated washings with pet. ether (60-80°) gave the crystalline products. . These complexes are monomeric in nature as inferred from their molecular weight determination in benzene by ebullioscopic methods. These vary from green to green-bluish in colour and are stable in dry atmosphere. These decompose on heating beyond 175°, without melting. These are soluble in common organic solvents and decompose on heating with dil. acids or alkalies. The analytical data is presented in Table 1. The cyclopentadienyl and indenyl rings are 'It-bonded to the metal atom and are aromatic in character as is indicated by usual IR bands 3 ,4. The symmetrical and the asymmetrical o-c-o stretching frequencies (cm ") of the complexes are: oxalate (1350, 1670), malonate (1360, 1690), succinate (1310, 1710), tarta- rate (1320, 1710) and phthalate (1400, 1750)5,6. In covalently bonded carboxylates, there is an increase in the asymmetric and decrease in (O-C-O) symmetric stretchings?'". Hence a comparison of the two frequencies with those of ionic salts on one
