Synthesis and Structural Studies of Co(II), Ni(II), Cu(II), Zn(II), Th(IV) and UO2(II) Complexes with 2-Acetylpyridine-4'-methylbenzoyl hydrazone

A number of Co(II), Ni(II), Cu(II), Zn(II), Th(IV) and UO2(II) complexes with 2acetylpyridine-4-methylbenzoyl hydrazone (APMBH), obtained by the condensation of 2acetylpyridine with 4-methylbenzoyl hydrazine are reported. The reaction of metal chlorides with APMBH lead to isolation of complexes having the general formulas [M(APMBH)(H2O)nCl2] (n=1, M=Co(II), Ni(II); n=0 , M=Zn(II), UO2(II)), [Ni(APMBH-H)Cl(DMSO)]2, [Cu(APMBH-H)Cl]2 and [Th(APMBH)2Cl2]Cl2. The reaction of metal acetate with APMBH in 1:2 molar ratio yields the deprotonated bis-complexes [M(APMBH-H)2] ( M= Co(II), Ni(II), Cu(II), Zn(II) and UO2(II)). The complexes have been characterized by elemental analysis, spectral (IR, UV-Vis) magnetic and molar conductance measurements, which revealed that APMBH act as neutral tridentate NNOdonor ligand in the metal chloride complexes (1, 2, 5-7) and as a monobasic tridentate ligand in the dimeric complexes (3, 4). The ligand also acts as a monobasic NNO-tridentate in the deprotonated bis-complexes (8-12). Octahedral structure is suggested for Co(II), Ni(II), Cu(II) and Zn(II) complexes (1-3, 8-11), dimeric square pyramidal structure for Cu(II) complex (4) and trigonal bipyramidal structure for Zn(II) complex (5). Uranyl complexes 7 and 12 are expected to have pentagonal bipyramidal and hexagonal bipyramidal structures respectively. Eight coordinate structure is proposed for Th(IV) complexe (6). The antibacterial activity of Cu(II) and Zn(II) complexes (5 and 10) against Gram-positive and Gram-negative bacteria has been tested and show moderate and high activity respectively.