FORMATION OF AN AGOSTIC BOND BY PROTONATION - CHARACTERIZATION BY NMR-SPECTROSCOPY OF [(MU-H)3M3(MU-3-ETA-2-HCR)(CO)9][SO3CF3] (M = RU, R = ET, CHPHCH2PH, M = OS, R = ME)

Protonation of (μ-H)3M3(μ3-CX)(CO)9(M = Ru, X = Et, CHPhCH2Ph; M = Os, X = Me) in HSO3CF3solution yields [(μ-H)3M3(μ3-η2-HCR) (CO)9]+, in which the proton has been shown by1H and13C NMR spectroscopy to add across a C–M edge. The agostic hydrogen is fluxionally exchanged among all three C–M bonds but does not exchange with the bridging hydrides. These protonated clusters prove to be more susceptible to reductive elimination of CH3X than their neutral precursors. When M = Ru and X = H, Cl, Br, and Ph, addition of acid causes immediate cluster decomposition. When X = Ph and CHPhCH2Ph, the reductive-elimination products toluene and 1,2-diphenylpropane have been identified. © 1990, American Chemical Society. All rights reserved.