METATHESIS OF 2-PENTENE WITH THE W(CO)6/CCL4/HV-SYSTEM - ROLE AND PHYSICAL-PROPERTIES OF THE PHOTOGENERATED PRECIPITATE

This paper describes the role and some characteristic properties of the precipitate formed upon irradiation of the W(CO)6/CCl4 catalyst system in the photoinduced metathesis of 2-pentene. It is shown that the precipitate is the active catalyst species and that the reaction therefore follows a heterogeneous pathway. Experiments show that CCl4 is only a reactant in the formation of the precipitate and plays no role as a cocatalyst in the metathesis of 2-pentene. It is also demonstrated that infrared spectroscopy may give a misleading picture of the catalytically active intermediates in this reaction. Attempts have been made to identify and characterize the active solid; at present the structural information points to an unstable polymeric W-C-Cl species.