Bond cleavage is an important step in catalytic reactions. We have studied theoretically such reactions using quantum chemistry computational methods. Recently, we are paying attention to such reactions induced by a silyl group migration in transition metal complexes, in which even some kinds of double bonds can be cleaved in addition to single bonds such as X-CN bonds (X=C, O, N) in nitriles. To clarify the mechanism of these double bond cleavages, we conducted DFT calculations for the model reactions of N,N-dimethylformamide (Me2NCH(=O)), N,N-dimethylthioformamide (Me2NCH(=S), and N-benzylidenemethaneamine (PhCH=NMe) with CpFe(CO)SiMe3. In these reactions, first the silyl group on the Fe atom migrates to the heteroatom (O, S, N) to form three-membered ring intermediate with a C-X single bond (X=O, S, N). Thus, these bonds are weakened due to ring strain and eventually the C=X bonds are broken. While their reaction pathways are similar, the energetics are largely dependent on the X atom; While cleavage of the double bond is easy when X=S and O, it is not when X=N. The reason for this difference will be discussed.

DFT study of double bond cleavage induced by silyl migration in Fe complex

2019 Fall National Meeting

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