Two contact-point chiral distinction: model CHFClBr dimers.

Dimers of the simple chiral molecule CHFClBr have been studied using a variety of computational approaches, including HF, MP2, and DFT B3LYP and the 6-31G*, 6-31++G**, and 6-311++G** basis sets. Both heterochiral and homochiral dimers were studied to allow analysis of the chiral distinction in these systems. The dimers were arranged in edge-to-edge orientations with assorted combinations of two contact-points ("2:2e") between the dimers. The monomers were constrained to tetrahedral symmetry. We demonstrate that chiral distinction does indeed occur in these two contact-point models. While the stabilization energies are driven by the interactions of the nearest atoms (contacts) in the complexes, the degree of chiral distinction is driven by the profile of changing atoms, which, in the present systems, are often the distal atoms of the complexes. Moreover, the chiral distinction does not correlate with the stabilization energies. The terms contact-points and interactions are defined. 2004 Wiley-Liss, Inc.