Theoretical study on H2 elimination pathways of silylenoid H2SiLiF with CH4, NH3, H2O, HF, SiH4, PH3, H2S, and HCl

Ab initio molecular orbital calculations have been performed to explore the reaction potential energy surfaces of silylenoid H2SiLiF with XH (n) hydrides, where XH (n) = CH4, NH3, H2O, HF, SiH4, PH3, H2S, and HCl. We have identified a previously unreported reaction pathway on each reaction surface, H2SiLiF + H-XH (n -1) -> H (n) XSiLiF + H-2, which involves H-2 elimination following the initial formation of an association complex via a four-membered ring transition state to form the substituted three-membered ring silylenoid H (n) XSiLiF and a H-2 molecule. This theoretical calculations suggest that (i) for H-2 eliminations there is a very clear trend toward lower activation barriers and more exothermic interactions on going from left to right along a given row in periodic table, and (ii) for the second-row hydrides, the H-2 elimination reactions are less exothermic than for the first-row hydrides and the reaction barriers are lower for X-S and Cl. Compared to the insertions of H2SiLiF into XH (n) , the H-2 elimination pathways should be unfavorable with higher barrier and lower exothermic.