Molecular heterogeneous metathesis catalysts: an attempted synthesis of surface-anchored alkylidenetungsten complexes

Abstract

The reactivity of the two alkylidynetungsten complexes, [W(CCMe₃)(CH₂CMe₃)₃] and [W(CCMe₃)Cl₃(dme)](dme = 1,2-dimethoxyethane), was determined with the surface of different inorganic oxides, such as silica, alumina, silica-alumina and niobia; their catalytic activity was tested for the metathesis of cis-pent-2-ene. The most efficient solids resulted from the interaction of these complexes with the surface of partially dehydroxylated niobia and silica–alumina. An attempt to identify the surface complexes on niobia (most active system) and silica (less active system) revealed the presence of a number of different anchored complexes, some of them bearing a neopentylidene ligand. The possible correlation between catalytic activity and some of the most probable surface entities is discussed.