Supramolecular cluster catalysis: Facts and problems

Organometallic catalysis is generally thought to proceed through a catalytic cycle which involves coordination of the substrate to the metal center and decoordination of the product after the transformation. The water-sol. trinuclear cluster cation [H3Ru3(C6H6)(C6Me6)2(O)]+ (1) and derivs. thereof seem to catalyze the hydrogenation of benzene under biphasic conditions without prior coordination of the substrate, the interactions between catalyst and substrate relying on supramol. host-guest contacts thanks to the hydrophobic pocket spanned by the three arene ligands in the catalyst mol. The concept of supramol. cluster catalysis, the isolation and characterization of the catalyst-substrate host-guest complexes postulated, as well as errors and problems with this chem. will be discussed. [on SciFinder(R)]