Ab Initio study of isomerization reaction from c-OSiH2O to t-OSiHOH

The isomerization reaction from c-OSiH₂O to t-OSiHOH, a vital reaction to understand the spontaneous ignition of silane, has been reinvestigated with Gaussian-2 theory and the CASSCF(6,6) method. It has been found that the reaction proceeds through two consecutive steps; i.e., c-OSiH₂O undergoes isomerization to yield w-OSiH₂O, and then the latter is converted to t-OSiHOH. The G-2 energy of the transition state of the latter process is 4.3 kcal/mol higher than that of the former. However, the G-2 energy of this higher transition state plus H atom is still 4.8 kcal/mol lower than that of the original reactants of SiH₃ + O₂.