Kinetics Database Resources
Title: Reactions of Silylene with Unreactive Molecules. I: Carbon Dioxide; Gas-Phase Kinetic and Theoretical Studies
Journal: J. Phys. Chem. A
Page(s): 4922 - 4927
Reference type: Journal article
CO2 + SiH2 → CO + H2Si=O
Measured rate of reaction of SiH2 (silylene) with CO2. Goes to SiH2O (silanone) plus CO. Also considered product channel SiO + CH2O (formaldehyde). Did G2 calculations to elucidate reaction pathways, intermediates, and transition states. Found that SiO + CH2O pathway although exothermic by about 66 kJ/mol was kinetically disfavored going through a transition state with a barrier of about 24 kJ/mol and a low A factor. In contrast, the SiH2O + CO channel proceeds through a barrierless addition of SiH2 to CO2 followed by a modest insertion step of about 12 kJ/mol to form chemically activated oxacyclopropanone ?SiH2C(O)O)- which is about 73 kJ/mol downhill, which then can rearrange and eliminate CO through a local transition state (about 16 kJ/mol relative to oxacyclopropanone, but ?7 kJ/mol downhill from reactants). The measured temperature dependence of the overall reaction had an apparent activation energy of about 16 kJ/mol, in good agreement with the computed transition state of about 12 kJ/mol for insertion step.
View full bibliographic record.
Rate constant values calculated from the Arrhenius expression: