Computational Study on the Kinetics and Mechanism of Mn-PNP Pincer Complex Catalyzed Addition Reaction Between Benzyl Cyanide and Cinnamonitrile.

Metal ligand cooperation (MLC) is a catalyst design technique where both the metal center and the ligand framework aid in the binding of the reactant. Recently, a first-row transition metal Mn-PNP pincer complex that works via an aromatisation-dearomatisation mechanism of MLC was reported for base-free dinitrile coupling. We perform microkinetic modeling of the pertinent reaction considering competitive binding of the reactants and branching pathways in the overall scheme. The experimentally reported product yield could be well reproduced by our proposed kinetic scheme. Our results suggest that the presence of water in the system is inhibitive and does not help with the tautomerism of the bound reactant, unlike the previous experimental results for an aliphatic nitrile. We analyze the transition states and intermediates involved in the competitive binding and branching pathways by Fukui function analysis and energy decomposition analysis to rationalize the computed reaction path. The underlying factors that influence the preference of one pathway or the other could be reasonably rationalized based on these analyses.