A Computational Outlook on Ascertaining the Reactivity of Transition Metal-Based Olefin Metathesis Catalysts

Abstract

Density functional theory (DFT) calculations were performed to evaluate the relative efficiencies of Nb-, Mo-, and W-based Schrock-type alkylidene complexes (1–11) in olefin metathesis. The study reveals that catalytic efficiency is strongly governed by the electrostatic nature of the M–C bond. A larger electrostatic contribution imparts greater ionic and polarizable character to the metal–carbene interaction, facilitating electron redistribution during olefin coordination and promoting efficient metallacyclobutane formation in the Chauvin mechanism. W-based complexes, particularly (7), (9), and (11), exhibit shorter M–C bonds, higher ν(M–C) frequencies, larger WBIs, and stronger orbital stabilization, indicating highly stabilized and more covalent metal–carbene interactions. In contrast, Mo complex (1) shows a larger electrostatic contribution, longer M–C bond distance, smaller charge separation, lower WBI, and lower steric congestion, indicating a more ionic and readily polarizable Mo–C interaction favorable for catalytic turnover. EDA, %VBur, and mechanistic analyses further demonstrate that although W complex (11) is thermodynamically more stable, its greater covalent stabilization and steric congestion reduce catalytic efficiency, whereas Mo complex (1) exhibits more favorable energetics for four-membered TS formation and is the most catalytically efficient system among the complexes studied herein, in accordance with experimental reports.