Reactions of σ-phenylethynyl derivatives of molybdenum and tungsten with HBF4 in the presence of n- and π-donor ligands. Crystal structures of [(eta5-cyclopentadienyl)-bis-(eta2-diphenyl-acetylene)(Monocarbonyl)molybdenUM]tetrafluoroborate and [(eta5-cyclopentadienyl)(eta2-diphenylacetylene)(eta2-phenylacetylene)(monocarbonyl)tungsten] tetrafluoroborate

Protonation of the complexes of [M]C=CPh (1) type, where M=Cp(CO)3Mo, Cp(CO)3W, aqueous HBF4 under different conditions, results in formation of instable cation vinylcarbene complexes ([.rg]-C+=CPhH)B anti F4, in which the M-C bond is easily cleaved and in the presence of L=RC2R'(R=H and R'=Ph, R=R'=Ph) ligands or PPh3 results in formation of corresponding complexes [Cp(CO)ML2]+BF-4, where M=Mo or W, is investigated. Under similar conditions the reaction 1, where M=Cp(CO)2(PPh3)Mo, with the PPh3 proceeds with formation of [Cp(CO)2(PPh3)Mo-C(PPh3)=CHPh]BF4 phosphorylide complex. PMR-temperature dependence of acetylene ligands rotation around metal-ligand bond in the [(Ph-CH)CpW(CO)(PhC-CPh)]BF4(2) tungsten complex is studied; the crystal structures of 2 and its phenylacetylene molybdenum analog are determined