Theoretical Study on the Silylidyne Insertion into NH3, H2O, HF, PH3, H2S, and HCl

Abstract

The reaction paths of the silylidyne insertion into NH3, H2O, HF, PH3, H2O, HF, and HCl have been studied by means of ab initio molecular orbital calculations incorporating electron correlation with Moller−Plesset perturbation theory up to the second and fourth order and using polarization basis sets augmented by diffuse functions. All these reactions involve the initial formation of an intermediate complex followed by a hydrogen-migration process via a transition state. Analyses for the reactivity of the six substrates in the SiH insertion reactions indicate that the reaction with the hydride of the right-hand group has a less stable complex and is more exothermic than with the hydride of the left-hand group and that the reaction with the second-row hydride has a lower overall barrier and is less exothermic than with the first-row hydride. Comparison with the CH and SiH2 insertion reactions has been made, and it is noted that the CH, SiH2, and SiH insertion reactions have similar reaction processes. The energetic results (for the barriers and reaction enthalpies) indicate that the SiH radical is less reactive than the CH radical in the insertion reactions.