TUNGSTEN(II) CHLOROCARBONYLS AS ALKENE METATHESIS, ARENE ALKYLATION AND ALKYNE POLYMERIZATION CATALYSTS

Tungsten(II) chlorocarbonyl compound obtained by photochemical oxidati on of W(CO)(6) with CCl4 is an active alkene metathesis catalyst, free of any organometallic component. This indicates that the initially fo rmed alkylidene ligand must come from the alkene. In toluene solution the same tungsten(II) compound also acts as a highly active catalyst f or the transformation of alkenes to alkyltoluenes. Tungsten(II) compou nds, which are formed in photochemical oxidation of W(CO)(6) with Grou p 14 tetrahalides, are extremely reactive at 25 degrees C in phenylace tylene polymerization. The results reported here clearly demonstrate t hat the formation of tungsten(II) might be an important event in the c reation by Lewis acids (Group 14 tetrachlorides) of the catalytic acti vity of tungsten(0) compounds.