New reactions of C-C bond cleavage and formation catalysed by silica-supported tantalum and tungsten hydrides

Silica-supported tantalum and tungsten hydrides present unusual properties in the activation of alkanes. They activate the CH bonds of cycloalkanes to form the corresponding surface metal-cycloalkyl complexes. They catalyse t he metathesis reaction of alkanes which is an unprecedented process affordi ng the formation of higher and lower homologues. They also catalyse the hyd rogenolysis of alkanes and especially ethane which cannot be cleaved by the corresponding group-4 metal hydrides. (C) 2000 Academie des sciences / Edi tions scientifiques et medicales Elsevier SAS.