Cobalt(III) Complexes with Quadridentate Ligands. VIII. The Preparation and Properties of Cis-β1 and β2-Isomers of the Thiosalicylato(quadridentate amine)cobalt(III) Complexes

Abstract

Abstract cis-β1 and β2-Thiosalicylato(quadridentate amine)cobalt(III) complexes, cis-β1, β2-[Co(thiosal)L]X·nH2O (L: trien (2,2,2-tet), 3,2,3-tet; X: Cl, NO3), have been prepared from a reaction mixture of [CoCl2L]Cl·nH2O (L: trien, 3,2,3-tet), Ag2O, thiosalicylic acid (o-mercaptobenzoic acid), and 28% aqueous ammonia. Two geometrical isomers (cis-β1 and β2) of their complexes were separated by Dowex 50W-X2 column chromatography. The isomerization between the cis-β1 and β2-isomers is reversible in water at 40 °C. The IR spectra of these complexes showed four or five absorption bands in the 990–1100 cm−1 region and four absorption bands in the 3000–3300 cm−1 region. This indicates that these complexes assume the cis-β1-form. Their cis-β1 and β2 configurations have been established by their absorption and NMR spectra. The cis-β1 and β2-thiosalicylato(trien)cobalt(III) complexes have been tentatively assigned to the RR,SS diastereoisomer by their 1H NMR spectra. The color of solid state materials, solubilities in alcohols, isomerization at 40 °C, reaction in 60% nitric acid, absorption spectra, and chemical shift of Co–S–C carbon of the coordinated thiosalicylato ligand for the title complexes are different from those of the corresponding cis-β1 and β2-salicylato(quadridentate amine)cobalt(III) complexes, cis-β1, β1-[Co(sal)L]Cl·nH2O (L: trien, 2,3,2-tet, 3,2,3-tet, 3,3,3-tet), reported previously.