Stereochemical Aspects of Optical Resolution of Octahedral Metal Chelates by Liquid Chromatography

Abstract

Discrimination of enantiomers of octahedral metal complexes should be done in a mechanism different from that of organic compounds having a tetrahedral asymmetric center. In this respect, the elucidation of the mechanism of optical resolution by chromatography has been one of the most fascinating subjects in coordination chemistry. Since metal complexes usually exist as ions, they are charged on ion-exchange resin and eluted into enantiomers with the eluent containing suitable chiralions(reso1ving agent). While so many chiral metal complexes can be resolved into enantiomers by way of diastereomeric crystals, comparatively few examples of complete resolution by chromatographic techniques have been reported. This is because there are only two resolving agents, d-tartrate and antimony d-tartrate, which are conveniently used for chromatographic separation(1). Here I will describe the outline of works which were done in my laboratory to clarify the mechanism of chromatographic resolution of metal chelates.