Investigation of Nature of The Active Species and Carbene Formation in Photocatalytic Metathesis Reaction

The nature of the active species which lead to the formation of the initiator carbene in photocatalytic metathesis reaction was investigated. The solid phase produced during irradiation was found to involve the active species while the soluble species showed no catalytic activity. The structure of the active solid was analyzed by ESCA, FT IR, NMR and chemical analysis methods and defined as a tunsgten complex, (CO)6nWCIn(n=2). The initiator carbene was determined as the tungsten-alkylidene complex, [W]=CHR1, derived from the active solid, instead of the diklorocarbene complex, ([W]=CI2), as suggested in the literature. The formation of Wittig-type addition products with benzaldehyde indicates that catalytically active carbene is the product of olefin and tungsten hexacarbonyl under reaction conditions.