Isolation of a diketone species that is allylically bound to tungsten, and its relationship to a tungsten η2-ketone complex

The diketone complex [W(CO)2(η-C5H4Me){η3-(H)C(O)C5Me5}] (3) was isolated from the reaction of PhC2H with a mixture of [Ni(CO)I(η-C5Me5)] and [W(CO)3(η-C5H4Me)]−. Complex 3 contains an organic diketone fragment that is bound in a π-allyl fashion to a tungsten atom. It was fully characterized by standard spectroscopic techniques and by a single-crystal X-ray diffraction study. The relationship of complex 3 to a structurally characterized cyclopentadienyl tungsten η2-ketone species 1, and the likelihood that 3 and the methylcyclopentadienyl analog of 1 share common intermediates, are discussed.