Carbon—carbon bond activation by homogeneous transition-metal catalysts has become a rapidly growing area of research due to its extensive range of applications in industry and complex organic molecule synthesis. Despite the significant progress that has been made in this field, the cleavage of thermodynamically stable and kinetically inert C—C σ-bonds under mild homogeneous conditions remains a challenge. The activation is primarily limited to systems in which either relief of strain, aromatization, or cooperative activation on the metal cluster serves as a driving force. A notable exception to this is the oxidative addition of unstrained C—CN bonds of nitriles. In this presentation, an update on the density functional theory calculations on the C—CN bond activation of a variety of fluorinated benzonitriles by [Ni(dmpe)] fragment will be reported. A thorough examination of the reaction profiles starting from the η2-nitrile complex and the C—CN bond activation product will be discussed. In addition to the 1D scans, two new potential energy surfaces were generated from the 2D scans. The energetics of the resulting nickel complexes, possible reaction intermediates, and transition state structures leading to the formation of the C—CN bond activation product in a polar and a nonpolar solvent will be presented. A total of 64 ground state structures and 80 transition state structures were located for 6 substrates (5 fluorinated benzonitriles and benzonitrile). Complexes with aryl groups containing two ortho fluorine substituents will be compared to those with a single ortho fluorine substituent. The dependence of the C—CN bond activation product stability and the energies of the transition states leading to the formation of these products on the number of ortho fluorine substituents and the total number of fluorine substituents will be presented. The results obtained from these calculations will be compared to the experimental data.

Update on the mechanistic investigation of the C—CN bond activation of fluorinated benzonitriles using a zerovalent nickel complex

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ACS Fall 2022

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