DFT Study on Mn–C Bond Dissociation Enthalpies of Manganese–Carbon Complexes in the Manganese‐Catalyzed C–H Alkenylation and Alkylation of Heteroarenes

Manganese‐catalyzed chelation‐assisted C–H alkenylation and alkylation of heteroarenes using alkynes or alkenes has emerged as an important and efficient strategy. In contrast to commonly used second‐ and third‐row transition metal catalysts, manganese systems exhibit broader substrate scope, accommodating both terminal and internal alkynes, and offer unique reactivity in C–H activation with advantageous atom‐ and step‐economy. In manganese‐catalyzed reactions between heteroarenes and unsaturated hydrocarbons, the formation of key manganese‐containing intermediates—particularly those involving Mn–C bond formation—plays a pivotal role in determining reaction outcomes. Our systematic theoretical investigation employed 10 DFT functionals to evaluate Mn–C bond dissociation enthalpy (BDE) values across 16 model complexes, revealing that the M05 functional provides optimal accuracy (RMSE = 2.8 kcal/mol) for these calculations. Subsequent M05‐based analyses of manganese–carbon complexes I and III, complemented by NBO and frontier molecular orbital studies, elucidated the substituent effects on Mn–C bond strength in these catalytic systems. Transition state characterization further uncovered a direct correlation between Mn–C bond strength and activation barriers, establishing a trend that connects thermodynamic stability with mechanistic feasibility in these manganese‐catalyzed transformations.