Non-covalent Interactions in Metal Complexes. II. Induction of Asymmetry in Cobalt(III) Complexes with Amino Acid-Schiff Bases. Importance of CH...?-Interaction in Determining Configuration of Complexes

Article abstract of DOI:10.1246/bcsj.53.2248

Cobalt(III) complexes, ^- and ^- (aa=ala^-, val^-, leu^-, phe^-), where H2(l-mop=aa) and H2(cop=aa) denote amino acid-Schiff bases of l-menthyl 3-(o-hydroxybenzoyl)propionate and cholesteryl 3-)o-hydroxybenzoyl)propionate, respectively, were prepared in solution.The intensity of the CD peak induced at 520 nm changes with the solvent used for preparation of the complex, decreasing in the order: ethanol, methanol, dimethyl sulfoxide, N,N-dimethylformamide and acetonitrile.Since the order corresponds to the increasing order of the CH..?-interaction between the solvent and benzene, it seems that the CH..?-interaction between the chiral group and the aromatic nucleus in the ligand plays an important role in determinig the configuration of the complexes.