DFT INVESTIGATION OF LEWIS ACID ASSISTED C-CN BOND ACTIVATION OF BENZONITRILE WITH [NI(DMPE)] FRAGMENT
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There has been recent interest in the field of organometallics with C—C bond activation of organic substrates that are mediated by transition metal complexes. The bond activation of C—C bonds is important, not only in organic synthesis but also in industrial processes. However, the activation of these bonds remains difficult since they are thermodynamically more stable and sterically less available to activate than the activation of the C—H bond. Most of the successful C—C cleavage uses the relief of ring strain, achievement of aromaticity, or proximity, as the driving force for the reaction.3 Another strategy is the use of a functional group such as nitrile and Lewis acid additivities. The studies looking at the mechanisms of C—C cleavage can be useful to develop new strategies for breaking C—C bonds. For this project, we compared the C—C bond activation transition state (TS) with and without Lewis acid coordination. There are two distinct TS structures found in the potential energy surface (PES) of C—C bond activation of benzonitrile without a Lewis acid, whereas there is only one TS structure on the PES with a Lewis acid. This suggests a post-transition state bifurcation for the Lewis acid assisted C—C bond activation with the [Ni(dmpe)] fragment. The structure of the C—CN bond activation products of benzonitrile with and without Lewis acid coordination are also reported.