J. Indian Chern. Soc., Vol. 83, September 2006, pp. 888-890 Oxovanadium(IV) complexes containing ONO donor hydrazone ligands derived from acetylacetone and acetylhydrazidelbenzoylhydrazide Tapas Ghosh* and Kumar Ranabir Sur Department of Chemistry, R. K. Mission V. C. College, P.O. Rahara, Kolkata-700 118, India E-mail : ictg_64@yahoo.co.in Manuscript received 4 October 2005, revised 4 May 2006, accepted 26 June 2006 Abstract : Two oxovanadium(tv) complexes [VO(L 1 )(CIIJOII)], 1 and [VO(J})(CibOII)], 2 were synthesized by the reaction of equi- molar amount of VO(acac)l with acetylhydrazide (Ilah) and VO(acac)z with bcnzoylhydrazide (lib h) respectively in methanol [(L 1 )2- and (L 1 )2- stand for the dianions of the hydrazone ligands produced by the condensation reaction of one of the two coordinated acetylacetonate moieties in VO(acac)z with llah and Ilhh respectively]. The complexes subnormal magnetic moment (Jlerr = 0.84 and 1.04 B.M. respectively, for complexes 1 and 2) at room temperature indicating appreciable antirerromagnetic interaction due to overlapping of two 3d,y orbitals of two vanadium atoms of the neighboring molecules through the formation of bridge via one of the two enolic-0 atoms. Keywords : Oxovanadium(IV) complexes, hydrazone complexes. Vanadium has received considerable attention as a biologi- cally important metal after the discovery of different type of enzymatic and physiological 1 • 2 activities of its com- pounds, which contain one of its two commonly occurring motifs V0 2 + and V0 3 +. Aroylhydrazone compounds of va- nadium have been reported to act as inhibitors of enzymes and antifungal/antibacterial agents 3 . Only a few V0 2 + com- plexes with hydrazone ligands in the mixed-ligand systems have been reported in which the hydrazone ligands arc formed by condensing benzoylhydrazine with either acetylacetone or salicylaldehyde, substituted salicylalde- hyde or benzoylacetone and acetylhydrazidc witl1 salicylaldehyde and 2-hydroxyacetophenone4- 7 . Recently two oxovanadi- um(tv} complexes with ONO donor hydrazone ligands de- rive·d from the condensation of salicylaldehyde with nicotinic acid hydrazide/2-furoic acid hydrazide have been reported by Maury a et al. 8 • The results of the study of oxo- vanadium(IV) complexes with two hydrazone ligands de- rived from the condensation of acetylacetone with acetylhydrazide/benzoylhydrazide have been reported in this paper. Results and discussion Two oxovanadium(tv) complexes 1 and 2 of the general formula [VO(L)(CH 3 0H)] [where, L 2 - is the general abbre- viation of the dianion of H 2 acac : ah (H 2 L 1 ) and H 2 acac : bh (H 2 L 2 ); H 2 acac : ah and H 2 acac : bh are the hydrazones of acetylacetone (Hacac), with acetylhydrazide (Hah) and Hacac with benzoylhydrazide (Hbh); two H's representing 888 the dissociable enolic and amide protons, (Ia) were synthe- sized in coordinated form by the in situ equimolar reaction ofVO(acach with Hah and Hbh, respectively in methanol]. These ligands bind with the vanadium through its enolate modes 4 - 7 (lb). Reactions can be represented in the follow- ing way: [VO(acac)2] + Hah CH30H • [VO(L 1 )(CHJOH)], 1 + Hacac [VO(acac)2] + Hbh _C_H_J_O_H__. [VO(L 2 )(CHJOH)], 2 + Hacac JR spectra and magnetic susceptibility of the complexes : Complexes display strong V=O stretching band at 985 cm- 1 indicating the hexacoordinated environment around the vanadium 4 · 6 . The absence of free N-H and C=O absorp- tions of the free Hah and Hbh indicates that they are con- densed with one of the two coordinated acac- moieties with the formation of corresponding hydrawne ligands in coor- dinated form and they are coordinated with the metal in a tridentate dinegative fashion through the enol form of the -CONH- bond. Two sets of bands one at 1279-1281 cm- 1 and other at 1397-1420 cm- 1 were assigned to the v(C-0) (enolato) Large shifting of the second set ofv(C- 0) (enolato) band compared to the first set towards the higher energy region indicates that it is involved in bridg- ing9. The band at around 1563-1571 cm- 1 may be assigned to the V(C=N) The band at -1027 cm- 1 is assigned