Synthesis of η2‐Allene Complexes by the Reaction of a η1‐Vinylidene Tungsten Complex with Diazoalkanes

The reaction of the η1-vinylidene complex Cp(CO)(NO)W=C=CH2 (5) with diazomethane, to give complex 8, as well as with ethyl diazoacetate, to give complexes 10 and 11, is described. The crystal structures of these complexes are reported. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)