Ab Initio energetics of SiO bond cleavage.

A multilevel approach that combines high-level ab initio quantum chemical methods applied to a molecular model of a single, strain-free SiOSi bridge has been used to derive accurate energetics for SiO bond cleavage. The calculated SiO bond dissociation energy and the activation energy for water-assisted SiO bond cleavage of 624 and 163 kJ mol , respectively, are in excellent agreement with values derived recently from experimental data. In addition, the activation energy for H O-assisted SiO bond cleavage is found virtually independent of the amount of water molecules in the vicinity of the reaction site.