Dipole moment derivatives in fluorosilanes

The results of ab initio (6-31G) molecular orbital calculations of the dipole moment derivatives in fluorosilanes are reported. Both the H- and F-atom polar tensors (APTs) appeared to be transferable among the fluorosilanes series, similar to the case of the fluoromethane series. The APTs in fluorosilanes are more isotropic than in fluoromethanes. This has been attributed to the more ionic character of the SiH and SiF bonds in fluorosilanes compared with the CH and CF bonds in fluoromethanes. According to the charge-charge flux-overlap analysis, the net charge effect was observed to be considerably more important in the APTs of fluorosilanes.