Isolation of a diketone species that is allylically bound to tungsten, andits relationship to a tungsten eta(2)-ketone complex

The diketone Complex [W(CO)(2)(eta -C5H4Me){eta (3)-C(O)-C(Ph)-C(H)-C(Ph)-C (H)-C(O)-C5Me5}] (3) was isolated from the reaction of PhC2H with a mixture of [Ni(CO)I(eta -C5Me5)] and [W(CO)(3)(eta -C5H4Me)](-). Complex 3 contain s an organic diketone fragment that is bound in a pi -allyl fashion to a tu ngsten atom. It was fully characterized by standard spectroscopic technique s and by a single-crystal X-ray diffraction study. The relationship of comp lex 3 to a structurally characterized cyclopentadienyl tungsten eta (2)-ket one species 1, and the likelihood that 3 and the methylcyclopentadienyl ana log of I share common intermediates, are discussed. (C) 2001 Elsevier Scien ce B.V. All rights reserved.