Revisited the mechanism of cobalt(III) catalyzed cyanation of arenes and heteroarenes: A DFT study

[Display omitted] •Mechanism of Cobalt catalysed CH cyanation of various arenes and hetero arene system.•The cyanation process is more facile under the assistance of single acetic acid.•Hetero arene substrate undergoes Co-catalysed CH cyanation more easily compared to arene substrates.•Involvement of second acetic acid plays a crucial role in demetallation step. Transition metal catalyzed cyanation of arenes and heteroarenes by CH activation is an attractive process for functionalization of aromatic system. One such reaction under the catalysis of cobalt complex using N-cyano-N-phenyl-p-toluenesulfonamide as a cyanating reagent was studied theoretically. Metal mediated cyanation of aromatic ring involving one and more acetic acid have been explored. Our finding reveals that during the metal mediated activation of CH bond, presence of two acetic acid, increase the activation energy of the proton abstraction step. Comparison of the energy profile diagrams for single and double acetic acid mediated steps shows that the pathway, assisted by single acetic acid, is energetically more favorable. The calculated apparent activation barrier of the reaction is also consistent with the experimental report and it also shows high temperature (120 °C) has been needed to carry out the reaction.