Coordination chemistry of benzoxazole-2-thione. Complexes of some transition metal acetates, tetrafluoroborates, sulphates and nitrates

Abstract

Abstract Several complexes of cobalt(II), nickel(II), copper(II), copper(I), zinc(II), cadmium(II)and mercury(II) acetate, tetrafluoborate, sulphate and nitrate with benzoxazole-2-thione have been prepared and characterized by chemical analyses, ligand-field spectra, magnetic susceptibility measurements, molecular conductances and vibrational spectra (conventional and far i.r.). In the light of spectroscopic investigation it is possible to distinguish whether the anions present are coordinated to the transition metal ion or are present as free ions. Spectroscopic parameters of the cobbalt(II) and nickel(II) complexes are compared with similar chromophores containing sulphur, oxygen and nitrogen donor atoms. The evidence suggests that the sulphato- and nitrato-derivatives of cobalt and nickel are tetrahedral, the nickel tetrafluoroborato-derivative resulted octahedral, while the nickel acetato-complex and the complexes of the cobalt acetate and tetrafluoroborate resulted square planar and in predominantly planar environment respectively. The zinc, cadmium and mercury derivatives with a 1:2 and 1:3 metal:ligand molar ratio have a tetrahedral symmetry with the exception of[Znbot 2 Ac 2 ] which resulted hexacoordinate with the acetato groups acting as symmetrical chelates. The complexes [ZnbotSO 4 ] and [CdbotSO 4 ] have a linear structure with the sulphate group acting as unidentate with a C 3ν symmetry, polymeric structures with the sulphate anion functioning probably as chelate and of symmetry lower than C 2ν being excluded from the i.r. evidence. Allocation for the possible metal-ligand and metal-anion modes have also been made.