First Example of the η3-Prop-2-ynyl Ligand; Synthesis and Reactivity of Cationic (η3-Prop-2-ynyl)arenedicarbonylmolybdenum Complexes; X-Ray Structure of [Mo(CO)2(η6-C6Me5H)(η3-HCCCH2)]+BF4−

A series of (η³-prop-2-ynyl)arenedicarbonylmolybdenum complexes with a novel η³-prop-2-ynyl ligand have been obtained, their structure has been established unambiguously by an X-ray diffraction study of a pentamethylbenzene derivative; the reactions of the η3-prop-2-ynyl derivatives with H₂O and PPh₃ yield complexes with 2-hydroxyallyl, 2-triphenyl phosphonioallyl and 1-triphenylphosphoionallene ligands.