N. Cabon, A. Le Goff, C. Le Roy, F. Y. Petillon, P. Schollhammer, J. Talarmin, J. E. McGrady, K. W. Muir



Publication year




Periodical Number






Author Address

Full version

A series of chemical and electrochemical transformations of systems in which a {Mo2CP2(mu-SMe)(3)} core is bridged by a mu-C2HnR ligand (n = 0-4) are described in this paper. The reaction of the alkylidene complex [Mo2Cp2(mu-SMe)(3)(mu-eta(1):eta(2)-CHCH(2)Tol)](BF4) (1) with LiBun at 0 degrees C produces the mu-sigma,pi-vinyl complex [Mo2Cp2(mu-SMe)(3)((mu-eta(1):eta(2)-CH=CHTol] (2) in good yield. The molecular structure of 2 has been confirmed by X-ray analysis. Upon treatment with NaBH4 1 is readily converted into the semibridging alkyl species [Mo2Cp2(mu-SMe)(3)(mu-CH(2)CH(2)Tol)] (3), which is also formed by electrochemical reduction of 1 in acidic medium. NMR and X-ray diffraction studies of 3 are consistent with, but do not definitively establish, the presence of a eta(1) alpha-agostic interaction. Density functional theory has been used to confirm the presence of agostic interactions in both 1 and 3 and also to explore the exchange pathways for these hydrocarbyl dimolybdenum systems. Electrochemical transformation of the mu-alkylidene complex 1 gives 3 as the major product when acid is present and a mixture of 2 and 3 when acid is absent, production of 2 being favored by low initial concentrations of 1. Theoretical, spectroscopic, and diffraction data are used to explain the formation and structures of closely related [Mo2Cp2(mu-SMe)(3)(mu-C2HnR](z+) complexes (n = 0-4 and z = 0, 1), including 1-3.