Preparation and Spectroscopic Studies of Cobalt(III) Complexes Containing Optically Active Seven-membered Chelate Ligands

Article abstract of DOI:10.1246/bcsj.54.2947

New cobalt(III) complexes of the types, trans-⁺, ³⁺, cis-³⁺, and ³⁺, where L denotes a seven-membered chelate diamine ligand, (R)-2-methyl-1,4-butanediamine or meso- and (R or S)-2,5-hexanediamine, have been prepared.The dichloro complexes decompose gradually even in the solid state, and rapidly in methanol.The ammine and ethylenediamine complexes are stable in acidic water, but decompose gradually in neutral water.The absorption and circular dichroism spectra of all the complexes have been recorded in aqueous or acetone solutions.The circular dichroism spectra in the first absorption band region are changed by the addition of sulfate ions, and the variation has been discussed in terms of the structure of isomers and the conformational instability of the seven-membered chelate rings.