On chirality transfer in electron donor-acceptor complexes. A prediction for the sulfinimine•••BF3 system

Stabilization energies of the electron donoracceptor sulfinimine center dot center dot center dot BF3 complexes calculated at either the B3LYP/aug-cc-pVTZ or the MP2/aug-cc-pVTZ level do not allow to judge, whether the N- or O-atom in sulfinimine is stronger electron-donor to BF3. The problem seems to be solvable because chirality transfer phenomenon between chiral sulfinimine and achiral BF3 is expected to be vibrational circular dichroism (VCD) active. Moreover, the bands associated with the achiral BF3 molecule are predicted to be the most intense in the entire spectrum. However, the VCD band robustness analyses show that most of the chirality transfer modes of BF3 are unreliable. Conversely, variation of VCD intensity with change of intermolecular distance, angle, and selected dihedrals between the complex partners shows that to establish the robustness of chirality transfer mode. It is also necessary to determine the influence of the potential energy surface (PES) shape on the VCD intensity. At the moment, there is still no universal criterion for the chirality transfer mode robustness and the conclusions formulated based on one system cannot be directly transferred even to a quite similar one. However, it is certain that more attention should be focused on relation of PES shape and the VCD mode robustness problem. Chirality. (C) 2011 Wiley Periodicals, Inc.