Preparation of Polynuclear (Diamine)telluratocobalt(III) Complexes

Abstract Penta- and hexa-nuclear condensates of mono(diamine)cobalt(III) complexes and tellurates have been prepared and some of the optically active isomers separated. They are [{Co(TeO6H4)(diamine)}(Te2O10){Co(TeO6H4)(diamine)}]6− (brown complexes) and [{Co(TeO6H4)(diamine)}(TeO6){Co(TeO6H4)(diamine)}]4− (blue complexes), where diamine=ethylenediamine, (R)-(−)-propylenediamine, and (R,R)-(−)-1,2-cyclohexanediamine. The structures have been determined from the visible and ultraviolet absorption and circular dichroism spectra; the electrostatic repulsion between cobalt(III) and tellurium (VI) atoms is considered in detail.