Theoretical studies of neutral silane-ammonia adducts

Ab initio calculations including electron correlation have been performed on the neutral species SiH4·NH3 and SiF4·NH3. The calculations involved complete optimization of all bonding parameters using second-order perturbation theory (MP2). Some of the energetics for the SiH4·NH3 adduct were computed at the optimized geometry using fourth-order perturbation theory (MP4). Both adducts are found to be bound, the silane adduct weakly and the silicon tetrafluoride adduct strongly. Full vibrational analyses have been carried out at the MP2 level of theory. Vibrational frequencies are reported for both adducts and compared to available matrix isolation data for the case of SiF4·NH3. © 1990.