Abstract
A new series of hexacoordinate cobalt(II), nickel(II) and copper(II) complexes of 5-(2-carboxyphenylazo)-2-thiohydantoin HL having formulae [LM(OAc)(H^sub 2^O)^sub 2^] · nH^sub 2^O (M = Co^sup II^, Cu^sup II^ and Ni^sup II^), [LM'Cl(H^sub 2^O)^sub 2^] · nH^sub 2^O (M' = Co^sup II^ and Ni^sup II^), [LCuCl(H^sub 2^O)]^sub 2^ · 2H^sub 2^O, [LCu(H^sub 2^O)^sub 3^](ClO^sub 4^) and [LCu(HSO^sub 4^)(H^sub 2^O)^sub 2^] were isolated and characterized by elemental analyses, molar conductivities and magnetic susceptibilities, and by i.r., electronic and e.s.r. spectral measurements, as well as by thermal (t.g. and d.t.g.) analyses. The i.r. spectra indicate that the ligand HL behaves as a monobasic tridentate towards the three divalent metal ions via an azo-N, carboxylate-O and thiohydantoin-O atom. The magnetic moments and electronic spectral data suggest an octahedral geometry for Co^sup II^ complexes, distorted octahedral geometry for both Ni^sup II^ and Cu^sup II^ complexes with a dimeric structure for [LCuCl(H^sub 2^O)]^sub 2^ · 2H^sub 2^O through bridged chloro ligands. The X-band e.s.r. spectra reveal an axial symmetry for the copper(II) complexes with unsymmetrical ΔM^sub s^ = ± 1 signal and G-parameter less than four for the dimeric [LCuCl(H^sub 2^O)]^sub 2^ · 2H^sub 2^O. The thermogravimetry (t.g. and d.t.g.) of some complexes were studied; the order and kinetic parameters of their thermal degradation were determined by applying Coats-Redfern method and discussed.[PUBLICATION ABSTRACT]