Supramolecular cluster catalysis:: A case study of benzene hydrogenation

The hydrogenation of benzene to give cyclohexane, catalysed under biphasic conditions by the water-soluble trinuclear arene ruthenium cluster cations [H3Ru3(C6H6)(C6Me6)(2)(O)](+) (1), [H3Ru3(C6H5Me) (C6Me6)(2)(O)](+) (2), [H3Ru3(1,4-MeC6H4Pri)(C6Me6)(2)(O)](+) (3), [H3Ru3(1,2,4,5-C6H2Me4)(3)(O)](+) (4), [H3Ru3{C6H5 (CH2)(2)OH}(C6Me6)(2)(O)](+) (5), and [H3Ru3{C6H5(CH2)(3)OH}(C6Me6)(2)(O)](+) (6), is believed to occur within the hydrophobic pocket spanned by the three arene ligands of the trinuclear cluster, thus forming a supramolecular catalyst-substrate host-guest complex. This paper is a short overview of our research efforts directed to a new catalytic concept for which we coined the term 'supramolecular cluster catalysis'.