Activation of the C–C bond provides a molecular basis for structure sensitivity in metal catalysis

Abstract

The catalytic activation of hydrocarbon C–H and C–C bonds converts petroleum into fuels and chemicals. Understanding of the structural and electronic effects that control the catalysis has been a goal of researchers for decades. A focal issue concerns the number of metal atoms in a catalytic site required for C–C bond rupture^1,2. Metal surfaces catalyse alkane hydrogenolysis (C–C bond breaking), but the catalytic sites are poorly defined^3,4; soluble, structurally defined transition metal complexes are not known to catalyse this reaction. Here we present evidence demonstrating that isolated mononuclear rhenium complexes on the surface of MgO catalyse alkene hydrogenation, but not C–C bond rupture; in contrast, ensembles consisting of three of the same rhenium complexes catalyse both alkene hydrogenation and rupture of the C–C bond of cyclopropane. These results provide a molecular foundation for structure sensitivity in surface catalysis and point the way to design of multicentre catalytic sites on surfaces^5–7.