Photoinduced metathesis reaction of C3H6 on supported MoO3 catalyst

Abstract

Ultraviolet irradiation of MoO₃ supported on porous Vycor glass (PVG) in the presence of C₃H₆ has been found to induce the formation of approximately equimolar amounts of C₂H₄ and 2-C₄H₈ as well as a small amount of CH₃CHO, suggesting that the metathesis reaction of C₃H₆ occurs. The dependence of the yields upon the excitation wavelength is in good agreement with the excitation band of the phosphorescence of MoO₃/PVG, which arises from the charge-transfer transition (Mo⁶⁺O^2–) [graphic omitted] (Mo⁵⁺—O^–).* The quenching of the phosphorescence of MoO₃/PVG and the decrease in the yield of C₃H₆ metathesis on adding O₂ and CO suggest that the photoinduced metathesis reaction is closely associated with the charge-transfer excited triplet state of MoO₃/PVG. From these results, together with those of e.s.r. experiments reported previously, the mechanism of the photoinduced C₃H₆ metathesis, especially the primary process of metal–carbene formation, is discussed.