Rational design of model Pd(ii)-catalysts for C–H activation involving ligands with charge-shift bonding characteristics

Abstract

In this work, five new palladium(II) complexes have been designed as the model catalysts for methane to methyl trifluoroacetate conversion. All these compounds are analogues of the well-established (bis-NHC)PdBr₂ complex (NHC, N-heterocyclic carbenes), derived by complexing the palladium(II) metal ion with the derivatives of bis-2-borabicyclo[1.1.0]but-1(3)-ene (bis-2BB) ligands using the sp² carbons. Our density functional theory calculation results suggest that the (bis-2BB)PdBr₂ catalysts outperform the popular (bis-NHC)PdBr₂ complex in the desired catalytic process, and further reveal that the charge-shift bonding in the bis-2BB ligands contributes to the improved catalytic performance. These findings may spark new ideas for experimental design of more efficient organometallic catalysts for C–H bond activation and functionalization.