Tungsten(VI) and molybdenumVI oxo-alkyl species. Their role in the metathesis of olefins

The complexes MOCl (neopentyl)3(M = Mo, W) can be isolated from solutions which are active in olefin metathesis, and although inactive alone, these species can be converted into very active catalysts; the syntheses of MO(neopentyl)4(M = Mo, W) are also reported.