DFT-Based Insights into Pd–Zn Cooperative Effects in Oxidative Addition and Reductive Elimination Processes Relevant to Negishi Cross-Couplings

The individual steps of a model Pd-catalyzed Negishi coupling between vinyl bromide and MeZnClS2 (S = THF), using Pd(PMe3)2 as catalyst, have been examined with the aid of DFT computations in THF solution with the B97D functional to gain further insight into the role of Pd–Zn interactions on the oxidative addition and reductive elimination steps. Comparisons between such processes taking place on monometallic Pd complexes and on bimetallic Pd–Zn complexes reveal a detrimental effect of Pd–Zn interactions in oxidative addition, whereas reductive elimination is favored by Pd–Zn cooperativity. Additionally, a cis transmetalation pathway has been characterized that complements previous studies involving trans complexes.