Interaction of zerovalent precursor complexes of tungsten (W(CO)5L) with the surface of η alumina results in a highly active metathesis catalyst. However, in order to reach this high level of activity it is necessary that the support is highly dehydrated and exhibits a Lewis acidity. Infrared spectro- scopy indicates that the precursor complex is interacting with the surface through WCO → Al complexation. This complexation gives rise to a strong decrease in electron density on tungsten which results in the departure of the ligand, L. A coordinatively unsaturated carbonyl species seems to be stabilised on the surface.
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