Efficient Room-Temperature Oxidation of Hydrocarbons Mediated by Tricopper Cluster Complexes with Different Ligands

• Published in: Advanced synthesis & catalysis Vol. 354; no. 17; pp. 3275 - 3282
• Main Authors: Nagababu, Penumaka, Maji, Suman, Kumar, Manyam Praveen, Chen, Peter P.-Y., Yu, Steve S.-F., Chan, Sunney I.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 26.11.2012; WILEY‐VCH Verlag; Wiley; Wiley-VCH
• Subjects: Activated; Alicyclic compounds; Alicyclic compounds, terpenoids, prostaglandins, steroids; Catalysis; Catalysts: preparations and properties; Catalytic reactions; Chemistry; Chemistry, Applied; Chemistry, Organic; copper; CH activation; epoxidation; Exact sciences and technology; General and physical chemistry; homogeneous catalysis; hydroxylation; Noncondensed benzenic compounds; Organic chemistry; Physical Sciences; Preparations and properties; Science & Technology; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; PARTICULATE METHANE MONOOXYGENASE; C-H activation; epoxidation; homogeneous catalysis; hydroxylation; copper; PEROXIDE; Cyclohexane derivatives; Hydrogen peroxide; Ligand; Oxygen transfer; Alcohol; Activation; Chemical reduction; Transient species; Styrene derivatives; Substrate specificity; Epoxidation; Oxidation; Copper; Catalytic reaction; Hydroxylation; Carbon-hydrogen bond; Enzyme; Cytochrome P450; Benzene derivatives; Transition metal; Aldehyde; Ketone; Polydentate ligand; C―H activation; Copper ion; Time of flight method; Homogeneous catalysis; Cyclohexane; Catalyst; Room temperature
• ISSN: 1615-4150; 1615-4169
• DOI: 10.1002/adsc.201200474

Six tricopper cluster complexes of the type [CuICuICuI(L)]1+ supported by a series of multidentate ligands (L) have been developed as oxidation catalysts. These complexes are capable of mediating the facile oxygen‐atom transfer to hydrocarbon substrates like cyclohexane, benzene, and styrene (C6H12, C6H6 and C8H8) upon activation by hydrogen peroxide at room temperature. The processes are catalytic with high turnover frequencies (TOF), efficiently oxidizing the substrates to their corresponding alcohols, aldehydes, and ketones in moderate to high yields. The catalysts are robust with turnover numbers (TON) limited only by the availability of hydrogen peroxide used to drive the catalytic turnover. The TON is independent of the substrate concentration and the TOF depends linearly on the hydrogen peroxide concentration when the oxidation of the substrate mediated by the activated tricopper complex is rapid. At low substrate concentrations, the catalytic system exhibits abortive cycling resulting from competing reduction of the activated catalyst by hydrogen peroxide. This behaviour of the system is consistent with activation of the tricopper complex by hydrogen peroxide to generate a strong oxidizing intermediate capable of a facile direct “oxygen‐atom” transfer to the substrate upon formation of a transient complex between the activated catalyst and the substrate. Some substrate specificity has also been noted by varying the ligand design. These properties of the tricopper catalyst are characteristic of many enzyme systems, such as cytochrome P450, which participate in biological oxidations.