Olefin oxide-supported organometallic catalysts

We report here a study of Zr, Nb, Cr, and Mo hydrocarbyl compounds grafted onto oxide supports as potential olefin polymerization catalysts and oxide-supported Mo and W 7r-allyl derivatives in olefin disproportionation catalyses. The interaction of these compounds with silica and alumina supports has been examined using ESR and IR, analyses to define the catalytic materials that result. Finally, we consider why chemical support of these organometallic compounds confers on them an enhanced catalytic activity. 

Metathesis is one of the attractive methods for the conversion of alkanes and olefins, and has been developed in both homogeneous and heterogeneous catalysis fields. In homogeneous catalysis, Mo alkyl alkylidene complexes have been known to be active catalysts for metathesis [45-48]. Basset and Coperet et al. [49-53] prepared surface organometallic catalysts, which are simple monoatomic systems with hydrides, alkyl alkylidenes, or alkyl alkylidynes of Group 5 or 6 metal complexes supported on oxide surfaces for alkane and olefin metatheses. 

Basset and his group have observed that propane and propene metathesis give similar Cn+i/Cn+2 ratios of cross-metathesis products on silica-supported tantalum-neopentylidene catalyst at 150°C. The olefin-metathesis activity of these Schrock-type supported complexes results from the presence of the silyloxy ligand (vide infra) - Organometallic complexes are bound to silica or alumina by reaction of soluble complexes and involve die formation of one or several bonds between the central metal and the oxygen atom of the oxide support. 

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