Stereoselectivities in Mixed Ligand Complexes of Cobalt(III), with l-Asparagine as a Ligand

Abstract

Abstract The [Co(ox)(l-aspNH2)(en)] complex as well as the [Co(l-aspNH2)3−n(l-asp)n]n− complexes (n=1,2) have been prepared and separated into their diastereoisomers by means of column chromatography. The structures of the isomers thus isolated have been characterized by their absorption, CD, and PMR spectra. Stereoselectivity in the [Co(ox)(l-aspNH2)(en)] complex has been found for the fac-Λ and mer-Δ isomers, and those in the [Co(l-aspNH2)3−n(l-asp)n]n− complexes, for the fac-Δ and mer-Λ isomers. These results have provided proof of the stereoselective effect due to the chelated l-aspar aginate ion.