Theoretical prediction of O-H, Si-H, and Si-C [sigma]-bond activation reactions by titanium(IV)-imido complex

The O-H ...-bond activation of methanol, the Si-H ...-bond activation of silane, and the Si-C ...-bond activation of methylsilane by titanium(IV)-imido complex (...) were theoretically investigated with DFT and MP2 to MP4(SDQ) methods. The O-H ...-bond activation of methanol occurs with small activation barrier (...) of 7.1 (14.6) kcal/mol and large exothermicity (...) of 65.8 (61.4) kcal/mol to afford ..., indicating that the O - H ...-bond activation occurs easier than the C - H ...-bond activation (... = 14.6 (21.5) kcal/mol and ... = 22.7 (16.5) kcal/mol), where DFT- and MP4(SDQ)-calculated values are presented without and in parenthesis hereafter. Though the OCH... group becomes anionic and the H atom becomes proton-like in this activation reaction, population changes more moderately occur than those of the C - H ...-bond activation. This is because the H - OCH.. bond is already polarized in methanol. In the Si - H ...-bond activation, two reaction courses were investigated; in one course, the product is ... in which the H atom and the ... group are bound to the N atom and the Ti center, respectively, while in the other course the product is ... in which the H atom and the ... group are bound to the Ti center and the imido N atom, respectively. Though the former reaction occurs with small ... value and large exothermicity, the latter reaction occurs easier with further smaller ... value of 2.6 (4.3) kcal/mol and larger ... value of 32.5 (34.1) kcal/mol than those of the former reaction. This is because the Ti - H bond energy is much larger than the ... one. The Si - C ...-bond activation occurs with moderate activation barrier of 19.1 (18.6) kcal/mol and considerably large exothermicity of 33.9 (37.7) kcal/mol. Based on these results, we wish to propose the theoretical prediction that the titanium(IV) - imido complex is useful for O - H, Si - H, and Si - C ...-bond activation reactions. (ProQuest: ... denotes formulae/symbols omitted.)