Accurate rate coefficients for 40 bimolecular substituted silylene addition reactions for silicon hydrides containing up to nine silicon atoms are calculated using the G3//B3LYP method. The overall reactions exhibit two steps: the reactants first meet to form an adduct, which then converts into a saturated silicon hydride. Values for the single-event Arrhenius pre-exponential factor, Ã, and the activation energy, Ea, are calculated from the G3//B3LYP rate coefficients corrected for internal rotations, and a group additivity scheme is developed to predict Ã and Ea. The values predicted by group additivity are more accurate than structure-reactivity relationships currently used in the literature, which rely on representative Ã values and the Evans-Polanyi correlation. The structural factors that have the most pronounced effect on Ã and Ea are considered, and the presence of rings is shown to influence these values strongly.
- Gas-phase reactions
- Quantum chemistry
- Reactive intermediates
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Physical and Theoretical Chemistry