Influence of geometry on reductive elimination of hydrocarbyl–palladium–carbene complexes

Abstract

The influence of spectator ligand bite angle and the twist angle of the carbene on the reductive elimination of N-heterocyclic carbenes (NHCs) from palladium bis-phosphine complexes has been investigated using density functional theory. The spectator bite angle was found to have a significant influence on both the activation energy (E_act) and the enthalpy of reaction. Widening of the bite angle was found to lower E_act and increase the enthalpy of reaction. In contrast, rotation of the carbene with respect to the PdL₂ plane was found to have little influence on E_act. At carbene twist angles approaching 0° however, relief of the increased steric strain provides a considerable driving force for the decomposition reaction.