Efficient catalytic oxidation of hydrocarbons mediated by tricopper clusters under mild conditions

Two tricopper complexes are developed for efficient oxidation of hydrocarbons. These catalysts are based on the tricopper cluster that has been shown to be capable of mediating facile O-atom transfer to a number of organic substrates upon activation by dioxygen. It is demonstrated that the two tricopper complexes [CuICuICuI(L)]+, with L = 3,3′-(1,4-diazepane-1,4-diyl)bis(1-(bis(pyridin-2-yl)methyl)amino)propan-2-ol (7-Dipy) and 3,3′-(1,4-diazepane-1,4-diyl)bis(1-thiomorpholinopropan-2-ol) (7-Thio), can sustain catalytic oxidation of cyclohexane to cyclohexanol and cyclohexanone with high turnover frequencies in the presence of H2O2 in acetonitrile under ambient conditions. These catalysts appear to be extremely robust, with turnover limited by the H2O2 available to drive the process. The turnover frequencies of the catalysts are found to depend linearly on the H2O2 concentration with a second-order rate constant of ∼1 × 10−2 mol−1 s−1.