Novel mixed tris-complexes of cobalt(III) with α- and β-amino-acids: isolation, adsorption chromatography, and absorption spectra

Abstract

All eight possible geometrical isomers of the mixed cobalt(III) complexes containing 5-membered glycinato- and 6-membered β-alaninato-metal chelate rings, [Co(β-Ala)_x(Gly)_3–x](I; x= 1 or 2), have been isolated by adsorption chromatography on a cation exchanger in the H⁺-form owing to the difference in basicities of carbonyl groups hydrogen-bonded to the resin; surprising dissimilarites in absorption spectra of meridional isomers arise from the differences in Co–O π-interactions influenced by the conformations of the 6-membered rings.