Ligating properties of a potentially tetradentate Schiff base [(CH3)2NCH2CH2N = CHC6H3(OH)(OMe)] with zinc(II), cadmium(II), cobalt(II), cobalt(III) and manganese(III) ions:: synthesis and structural studies

A series of Zn(II), Cd(II), Co(II), Co(III) and Mn(III) complexes with the Schiff base [(CH3)(2)NCH2CH2N= CHC6H3(OH)(OMe)], LH, derived from 2-dimethylaminoethylamine and o-vanillin, has been synthesised and structures of all the products have been established by X-ray crystallography. In the cases of zinc and cadmium, dimeric complexes [Zn(LH)(2)(NCS)] [Zn-2(L)(mu(1,1)-CH3COO)(NCS)(3)] (1), [Cd-2(L)(2)(Cl)(2)] (2) and [Cd-2(L)(2)(NCS)(2)] (3), and for cobalt and manganese, monomeric complexes [Co(LH)(2)(NCS)](2) [Co(NCS)(4)] ( 4), [Co(LH)(2)(NCS)] ClO4 (5), [Co(L)(N-3)(o-vanillinate)] . 0.5MeOH (6) and [Mn(LH)(2)(MeOH)(2)](ClO4)(3) (7), are formed with various terminal ligands. All the complexes have been characterised by elemental analysis and IR spectra. UV-Vis and NMR spectroscopy, magnetic, and electrochemical studies, were also carried out where feasible. The Schiff base functions as a bi-, tri- or tetra-dentate chelating agent and coordinates via the protonated or deprotonated phenolic oxygen, amine and imine nitrogens, and only in case of 1 with the methoxy oxygen atoms, to the metal ion leading to the formation of mono- or bi- metallic complexes.