Ab initio investigation of the structures and stabilities of the donor-acceptor complexes H 3PBF 3 and Me 3PBF 3

Abstract

The structures of the complexes H 3PBF 3 and Me 3PBF 3 are determined from ab initio electronic-structure calculations. In contrast to gas-phase experiments, H 3PBF 3 is found to give only a weak van der Waals complex with a P—B distance of 349 pm (SCF) and 322 pm (MP2), whereas the experimental value is 192 pm. The corresponding dissociation energies are 8.0 and 12.7 kJ/mol, respectively. These results are confirmed by coupled-pair functional calculations. The methods employed are checked by calculations on Me 3PBF 3, where deviations from experiment are in the expected range.