CH Bond Activation Mechanism by a High-Valent Dinuclear Copper Complex: Unraveling the Effect of a Base by a Theoretical Study

Abstract

Recently, an electrochemically monooxidized dinuclear copper(II) complex [Cu₂(L)(μ-OH)₂]²⁺ with the dipyridylethane naphthyridine ligand (L) has been shown to activate the recalcitrant aliphatic C_sp³H bond of toluene (bond dissociation free energy, BDFE = 87.0 kcal mol⁻¹) at room temperature. The mechanistic pathway turns from stoichiometric to catalytic upon addition of a base (2,6-lutidine), suggesting a modification of the reactive species. Herein, we report theoretical calculations to characterize the reactive species and obtain a detailed understanding of the reactivity. Since different electronic structures are possible for these high valent systems, we perform DFT calculations coupled to CCSD(T) ones using the DLPNO-CCSD(T) scheme. Our results show that the presence of a base will impact the nature of the reactive species but also the type of mechanism involved in the CH activation.