Formation of the high-energy isomer HSiO + by chemical reaction in the gas phase

Abstract

The high-energy isomer HSiO + of protonated SiO has been generated by a fast O-atom transfer reaction between SiH + and N 2O in helium and hydrogen buffer gases at 0.35 Torr and 295±2 K. Formation of HSiO + by O-atom transfer proceeds in competition with formation of the ground-state SiOH + isomer, which is formally an insertion reaction. Other insertion reactions were observed in the reactions of SiH + with CO 2 and SO 2. The mechanism of insertion is rationalized in terms of sequential O-atom transfer and isomerization of HSiO + to SiOH + within the intermediate complex, where the isomerization may be achieved via a proton shuttle within the complex or unimolecularly, when sufficient excess energy is available in the initial O-atom transfer. The high-energy isomer HSiO + does not convert to SiOH + by reaction with H 2 at the operating conditions of the experiments.