COMPLEXES OF Ti(IV) AND Zr(IV) WITH SOME BIDENTATE SCHIFF BASES DERIVED FROM ISATIN

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1 CMPLEXES F Ti(IV) AD Zr(IV) WITH SME BIDETATE SCHIFF BASES DEIVED FM ISATI Angela Kriza, Caren Pârnău, Florica Zălaru, Angela F. Kriza Six ne etal chelates of Ti(IV) and Zr(IV) ith the Schiff base ligands fored by condensation of isatin ith aroatic aines (aniline, p-toluydine, -nitro-aniline) have been synthesized and characterized by eleental analysis, infrared, electronic spectral data and olar conductivity easureents. In different conditions, to kinds of coplexes of the sae Schiff Base ere obtained, Ti 4 (HL) and Zr 2 L 2. The ligands behaves as bidentate. Conductance data reveal a non-electrolytic nature of the coplexes. Introduction Although uch attention has been directed to study the etal coplexes of the Schiff base ligands derived fro isatin [1 7], no investigations have appeared in literature to describe the M(IV) (M=Sn(IV), Ti(IV) and Zr(IV)) coplexation of Schiff bases derived fro isatin ith aroatic aines. In vie of versatile iportance of isatins [8 12], and in continuation of our previous ork dealing ith the Sn(IV) and Zr(IV) coplexes of isatin Schiff bases [13 16], e herein, deeed desirable to report the synthesis and identification of the etal coplexes of Ti(IV) and Zr(IV), ith Schiff Bases derived fro isatin and aniline / p-toluydine / -nitro- aniline, hereafter abbreviated: HIA (isatin - aniline Schiff Base), HIPT (isatin - p-toluydine), HIMA (isatin - -nitro-aniline). = H, p-ch 3, - 2 Fig. 1: Schiff bases In different conditions, to kinds of coplexes of the sae Schiff Base ere obtained, Ti 4 (HL) and Zr 2 L 2, here HL are the Schiff Bases entioned above. Professor, lecturer, reader - Faculty of Cheistry, Departent of Inorganic Cheistry, University of Bucharest, school - istress I - School Andrei Şaguna, MAIA

2 38 AGELA KIZA CAME PÂĂU FLICA ZĂLAU AGELA F. KIZA Experiental All reagents used ere of analytical grade. Ti 4 (iedel), Zr 4 (Merck), aniline, p-toluydine -nitro-aniline (Aldrich) ere used ithout further purification. Anhydrous ethanol as obtained using the ethod presented in literature [17]. Synthesis of the ligands ere ade according to our previous ork [14]. Synthesis of coplexes [Ti 4 (HL)] coplexes have been prepared by ixing anhydrous ethanolic solutions of Schiff Base and etal chloride in 1:1 olar ratio under nitrogen atosphere at ph=6.5. The ixture as stirred during one hour under nitrogen atosphere and than as refluxed on a ater bath for 8 hours. The solvent excess as distilled. [Zr 2 L 2 ] coplexes ere prepared by addition of etal chloride (0.01 ol) in 50 l anhydrous ethanol to a hot ethanolic solution of the ligand (0.02 ol / 50l); then, under nitrogen atosphere and continuous stirring, sodiu ethoxide as added until ph reaches 7.3. The reaction ixture as refluxed on a stea bath for 4 hours. The coplexes ere precipitated upon concentration. The copounds ere filtered, ashed ith anhydrous ethanol and dried over P 2 5 in vacuu. Cheical analysis C, H and ere deterined by icro-analytical ethods. The etal and chloride ere estiated gravietrically [18]. Ti 4 (HIA) Calc: Ti 11.75; 34.51; 6.78%. Found: Ti ; ; 6.80%. Ti 4 (HIPT) Calc: Ti 11.22; 33.50; 6.76%. Found: Ti ; ; 6.80%. Ti 4 (HIMA) Calc: Ti 11.21; 33.45; 6.55%. Found: Ti ; ; 6.57%. Zr 2 (IA) 2 Calc: Zr ; 11.70; 9.32%. Found: Zr ; 11.75; 9.26%. Zr 2 (IPT) 2 Calc: Zr ; 13.42; 10.47%. Found: Zr ; 13.34; 10.52%. Zr 2 (IMA) 2 Calc: Zr ; 9.82; 12.25%. Found: Zr ; 10.23; 12.10%. Electronic spectra ere recorded in range n on a UICAM UV/VIS Spectroeter UV 4. The I spectra ere recorded in range c -1 ith a BI-AD FTS 135 spectrophotoeter, using KBr pellets. Molar conductivities ere easured in freshly prepared 10-3 ol.d -3 solutions in DMF at roo teperature ith a digital conductivity eter Consort C 533. esults and Discussion The Schiff Bases under present consideration react ith titaniu(iv) and zirconiu(iv) chlorides in anhydrous ethanol ediu, to give colored aorphous copounds, stable in air. They decopose at higher teperature ( C) and are insoluble in ost coon organic solvents.

3 CMPLEXES F Ti(IV) AD Zr(IV) WITH SME BIDETATE SCHIFF BASES 39 Eleental analysis data suggest 1:1 or, respectively 1:2 etal : ligand stoichioetries, the general forula, in each being Ti 4 (HL), respectively Zr 2 (L) 2. The conductivity values for the [Ti 4 (HL)] coplexes (in DMF, 10-3 ol, 25 C), ranging in the Ω -1.c 2.ol -1 region, indicate that the non-electrolytic nature of the copounds. This suggests that the anions are covalently bonded. The ost iportant I bands, presented and assigned in Table 1 sho the folloing characteristics: The three bands appearing at 3190, 1740 and 1654 c -1 in the ligands spectra, ere assigned to stretching vibration odes ν H, ν C= and ν C= respectively. In the cases of the [Ti 4 (HL)] copounds, the spectra reveal that the band having a axiu at 1740 c -1 in the free ligands is shifted to loer ave nubers. This shift indicates the iplication of carbonyl oxygen in the coordination at the etallic center. The band appearing at 1650 c -1 in the free ligands, assignable to the ν C= vibration ode, is shifted to loer ave nubers ith a ν = 35 c -1 in the coplexes spectra, this indicating the participation of azoethinic nitrogen ato in coordination. The band due to the ν H vibration ode in isatin, having the axiu at 3190 c -1 in the free ligands, reains largely unaffected in the chelates. Table 1. Infrared spectra (c -1 ) Copound ν H ν C= ν C= ν C=* ν C- ν M- ν M- HIA 3191,br [Ti 4 (HIA)] s 1708 [Zr 2 (IA) 2 ] - - HIPT 3180,br [Ti 4 (HIPT)] s 1710 [Zr 2 (IPT) 2 ] - - HIMA 3192,br [Ti 4 (HIMA] s 1717 [Zr 2 (IMA) 2 ] s s s The ost iportant conclusion dran fro this discussion is that the HL Schiff Base ligand is coordinated to the central etal ion as bidentate ligand. The free bonding sites are the central azoethine nitrogen ato and the oxigen of the carbonyl groups.

4 40 AGELA KIZA CAME PÂĂU FLICA ZĂLAU AGELA F. KIZA The bands assigned to stretching vibration odes ν H and ν C= in the free ligands disappear in the spectra of the [Zr 2 L] copounds, but ne bands are recorded at 1570 and 1225 c -1. These ne bands, assigned to the ν C= * (ne azoethine bond) and ν C- vibration odes respectively, suggest the enolysation of H hydrogen of isatin and the coordination at titaniu/zirconiu through the oxygen of the C- group. The band appearing at 1650 c -1 in the free ligands, assignable to the ν C= vibration ode, is shifted to loer ave nubers in the coplexes spectra, this indicating the participation of azoethinic nitrogen ato in coordination. In this case the HL, Schiff Base ligand, is coordinated to the central etal ion as uninegative bidentate ligand. The foration of M- and M- bonds is further supported by the appearance of ν M- and ν M- in the regions and c -1 respectively in the spectra of chelates [19]. The electronic spectra of the ligands in ethanol exhibit three bands at 230 n (π π * ), 290 n (n π * ) and 380 n. The diffuse reflectance spectra are siilar and shifted toard loer frequencies abs. (arb. units) avelenght (n) Fig. 2: Electronic spectru (diffuse reflectance tehnique) of HIA. In the visible region, the bands of the ligands, appearing at ~ 400 n, are less intense. The Ti(IV) and Zr(IV) chelates are diaagnetic ith no ligand field transition. In the [Ti 4 (HL)] coplexes spectra the bands are shifted ith about 20 n to loer frequencies, proving the ligands coordination at etallic center (Fig. 3). In the Zr 2 L 2 coplexes spectra these bands are shifted toard loer frequencies or is replaced by ore coplicated bands of different intensities [20], indicating a ore accentuate conjugation beteen the azoethine group and the aroatic ring (Fig. 4).

5 CMPLEXES F Ti(IV) AD Zr(IV) WITH SME BIDETATE SCHIFF BASES 41 Fig. 3: Electronic spectru (diffuse reflectance tehnique) of Ti 4 (HIA) Fig. 4: Electronic spectru (diffuse reflectance tehnique) of Zr 2 (IA) 2 The correlation of the experiental data allos assigning a octahedral stereocheistry to all the reported coplex copounds. The proposed structural representations are presented in Fig. 5:

6 42 AGELA KIZA CAME PÂĂU FLICA ZĂLAU AGELA F. KIZA H Ti Zr Fig. 5: Propose structures of coplex copounds:ti 4 (HL) and Zr 2 L 2 Conclusion We report here the synthesis and the characterization of six ne coplexes of titaniu (IV) and zirconiu (IV) ith Schiff Bases derived fro isatin and aniline / p-toluydine / - nitro- aniline. The syntheses ere conducted in conditions alloing the bi-dentate (neutral or ono-basic) function of the ligands. Varying the conditions under these requireents, to kinds of coplexes of the sae Schiff Base ere obtained, [Ti 4 (HL)] and [Zr 2 L 2 ], here HL are the Schiff Bases entioned above. The synthesized copounds ere characterized by eleental analysis, I, electronic spectroscopy, as ell as by conductance easureents. EFEECES 1. Khulb,. C., Bhoo, Y. K. and Singh,. P. (1981) J. Indian Che. Soc. 58, Peshkora, V. M., Barbalat, Y. A. and Polenova, T. V. (1976) Zh. eorg. Khi. 21, Taha, F. I. M. and Khatab, M. A. (1970) UA J. Che. 13, san, M. M. and Aer, M. (1983) Egypt. J. Che. 26, Gary, B. S., Singh, P. K. and Gary, S. K. (1991) Indian J. Che. 30A, Bhardaj, S., Ansari, M.. and Jain, M.C. (1989) Indian J. Che. 28A, Abu El-eash, G. M., Taha, F., Shallaby, A.M. and El-Gaal,. A. (1991) Indian J. Che. 30A, Vara,.S. and Khan, I. A. (1978) Indian J. Med. es. 67, 315.

7 CMPLEXES F Ti(IV) AD Zr(IV) WITH SME BIDETATE SCHIFF BASES Popp, F. D. and Pajouhesh, M. (1988) J. Phar. Sci. 17, Vara,.S. and obles, W. L. (1975) J. Phar. Sci. 64, Popp, F. D., Parson, D. and Doningan, B. E. (1980) J. Heterocyclic Che. 17, Kontz, F. (1973) Sci. Phar. 41, Kriza, A., Pârnău, C. and Popa,. (2001) ev. Chi. 6, Kriza, A. and Pârnău, C. (2001) Acta Chi. Slov. 48, Kriza, A., Pârnău, C. and Popa,. (2002) Anal. Univ. Buc., Ser. Chi. XI(I), Kriza, A., Pârnău, C., Popa,. and Udrea, S. (2002) Soc. Chi. Tunis (in press). 17. Vogel, A. I., (1968 ) A text book of rganic Cheistry, 3rd ed., ELBS, London. 18. Vogel, A. I., (1971) A text book of Quantitative Inorganic Analysis, 3rd ed., ELBS, London. 19. Khalifa, M. A. and Hassaan, A. M. (1995) Indian J. Che. 34(A), Hassaan, A. M. A. and Shehata, A. K. (1993) Synth. eact. Inorg. Met. rg. Che. 23(5), 815.