THEORETICAL-STUDY OF THE REACTION-MECHANISM FOR THE INTERACTION OF SI+ WITH DISILANE

The reaction mechanism for the interaction of Si+ with disilane has been studied by means of accurate ab initio molecular orbital techniques including polarized basis sets, effects of electron correlation, and zero-point corrections. There are two main accessible channels for the reaction, via Si+ insertion into the Si-Si or the Si-H bonds. While both are exothermic and lead to the same products, the Si-Si insertion channel is the lower energy pathway. The insertion is followed by 1,2-H shift and H2 elimination reactions. The reaction leads to the formation of two Si3H4+ isomers, a noncyclic isomer, H3Si-SiH-Si+, and a cyclic isomer, c(HSi-SiH2-SiH)+, with no overall activation barriers. Formation of silane and Si2H2+ is calculated to be significantly exothermic. Other fragmentation channels leading to the ions Si2H5+, Si2H4+, and Si2H3+ are calculated to be endothermic. Our results are in good agreement with the available experimental results. We compare our results to those from previous studies of the interaction of Si+ with silane and methylsilane.