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.

Graphical abstractTwo tricopper clusters have been developed as oxidation catalysts capable of converting cyclohexane to cyclohexanol/cyclohexanone with high efficiency at room temperature upon activation by H2O2. These catalysts are robust and exhibit properties similar to enzymes with substrate specificity as well as well-defined input and output states for control of turnover..Figure optionsDownload full-size imageDownload high-quality image (204 K)Download as PowerPoint slideHighlights► Tricopper clusters are developed as oxidation catalysts for cyclohexane (C6H12). ► These catalysts convert C6H12 to cyclohexanol and cyclohexanone at room temperature. ► With high turnover frequencies and numbers, the catalysts are efficient and robust. ► Activation of the tricopper cluster by O2 or H2O2 harnesses a “singlet oxene”. ► Atom transfer occurs when the substrate complexes with the activated catalyst.