Direct Benzene Hydroxylation with Dioxygen Induced by Copper Complexes: Uncovering the Active Species by DFT Calculations

The direct oxidation of benzene into phenol using molecular
oxygen
at very mild temperatures can be promoted in the presence of the copper
complex TpBr3Cu­(NCMe) in the homogeneous phase in the presence
of ascorbic acid as the source of protons and electrons. The stoichiometric
nature, relative to copper, of this transformation prompted a thorough
DFT study in order to understand the reaction pathway. As a result,
the dinuclear species TpBr3CuII(μ-O•)­(μ-OH)­CuIITpBr3 is proposed
as the relevant structure which is responsible for activating the
arene C–H bond leading to phenol formation.