X-RAY AND MOLECULAR-STRUCTURE OF THE DIASTEREOMERIC PAIR [LAMBDA-CO(EN)3][DELTA-CO(EN)(OX)2]I2.3H2O AND [DELTA-CO(EN)3][DELTA-CO(EN)(OX)2]I2.H2O AND COMPARISONS WITH [LAMBDA-CO(EN)3][DELTA-CO(GLY)(OX)2]I.H2O

The structures of the diastereomeric pair [LAMBDA-Co(en)3][DELTA-Co(en )(ox)2]I2.3H2O and [DELTA-Co(en)3][DELTA-Co(en)(OX)2]I2. H2O and the s alt [LAMBDA-Co(en)3][DELTA-Co(gly)(ox)2]I.H2O have been determined by X-ray crystallography. [LAMBDA-Co-(en)3][DELTA-Co(en)(OX)2]I2.3H2O cry stallizes in the monoclinic space group P2, (No. 4) with Z = 2, a = 11 .270(1) angstrom, b = 9.318(1) angstrom, c = 13.070(2) angstrom, beta = 100.68(1)-degrees, and R = 0.032 for 6825 reflections. [DELTA-Co(en) 3][DELTA-Co(en)(ox)2]I2.H2O crystallizes in the orthorhombic space gro up P2(1)2(1)2(1) (No. 19) with Z = 4, a = 10.773(1) angstrom, b = 12.8 94(1) angstrom, c = 18.941(3) angstrom, and R = 0.058 for 6339 reflect ions. [LAMBDA-Co(en)3][DELTA-Co(gly)(ox)2]I.H2O crystallizes in the or thorhombic space group P2(1)2(1)2(1) (No. 19) with Z = 4, a = 10.332(1 ) angstrom, b = 10.670(2) angstrom, c = 21.488(3) angstrom, and R = 0. 039 for 5818 reflections. Comparison of the modes of crystal packing w ith a description of the ion-pairing interaction obtained from solutio n studies provides insight into the mechanism of chiral discrimination , particularly the role of hydrogen bonding. The importance of hydroge n bonding and electrostatic attraction in determining the nature of th ese interactions and the mechanism of chiral discrimination is discuss ed.