MECHANISM OF OPTICAL RESOLUTION OF OCTAHEDRAL METAL-COMPLEXES

The study of the chiral discrimination between antimony d-tartrate and a series of [Co(N)(6)](3+) complexes reveals that chiral discrimination is effected by this anion through hydrogen-bonding association along the C-2 or C-3 axis of the complex. Furthermore, it is clear that the antimonyl d-tartrate ion favors the A-complex in the C-3 association, while it favors the Delta-complex in the C-2 association. A concrete association model is proposed to account for the mode of chiral discrimination between the complex and the antimonyl d-tartrate ion. The fundamental idea underlying this association model has been applied to the interpretation of the chiral discrimination between complex cations and complex anions. The C-3(+) complex cation always favors the homochiral combination (Delta-Delta or Lambda-Lambda) with the complex anion, while the C-2(+) complex cation always favors the heterochiral combination (Delta-Lambda or Lambda-Delta) with the complex anion. This tendency is explained by assuming that straight N-H...O hydrogen bonds are formed in such a favorable pair. This hydrogen bonding association model has made possible the highly efficient optical resolution of electrically neutral tris(aminoacidato)cobalt(III).