Potential primary pyrolysis processes for disilane

Four competing unimolecular decomposition pathways for disilane are considered with use of MP4 energies obtained with an extended basis set and geometries obtained at the MP2/6-31G** computational level. The 1,1- and 1,2-eliminations of H/sub 2/ and the elimination of silylene to form silane all have similar endothermicities, but the very high activation energy for the 1,2-elimination eliminates this process as a significant contributor at low energies. If disilene is formed in the thermal decomposition of disilane, the more likely source is its higher energy isomer silylsilylene via a relatively low energy 1,2-hydrogen shift.