GREEN AND ORANGE CRYSTALLINE FORMS OF ETHOXYSALICYLIDENE-(R,R)-1,2-CYCLOHEXANEDIAMINE)], SEPARATION OF THE DIASTEREOMERIC PAIR, AND ISOMERIZATION BETWEEN THEM IN THE SOLID-STATE

A pair of diastereomers, I and II, of the titled complex were separate d by liquid chromatography, and each of them crystallized in two diffe rent colors, green and orange. I(green) and II(green) were assigned to a mononuclear square pyramidal structure, while I(orange) and II(oran ge) to a polynuclear linear chain structure. The orange complexes turn ed green by heating at 195 degrees C in a few minutes. All of the four complexes undergo isomerization at 195 degrees C in the solid state t o give an equilibrium mixture, I:II approximate to 1:1.