mu-alkylidyne and mu-alkylidene complexes from a bridging side-on vinylidene sulfur-rich dimolybdenum precursor

Reaction of the It-vinylidene complexes [Mo-2(eta(5)-C5H5)(2)(mu -SMe)(3)(mu-eta(1):eta(2)-C=CHR)](BF4) (1; R = Tol (1a), n-Pr (1b)) with NaBH4 produced the mu-alkylidyne derivatives [Mo-2(eta(5)-C5H5)(2)(mu-SMe)(3)(mu-SMe)(3)(mu-CCH2R)] (2; R = Tol (2a), n-Pr (2b)) in good yields. Upon treatment with HBF4.Et2O 2a and 2b were readily converted into the mu-alkylidene species [Mo-2(eta(5)-C5H5)(2)(mu-SMe)(3)(mu-eta(1):eta(2)-CHCH2R)](BF4) (R = Tol (3a), n-Pr (3b)). NMR studies on these mu-alkylidene complexes revealed alpha-agostic interactions.