ja5b05571_si_001.cif (5.47 MB)

Donor-Promoted 1,2-Hydrogen Migration from Silicon to a Saturated Ruthenium Center and Access to Silaoxiranyl and Silaiminyl Complexes

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posted on 22.07.2015, 00:00 by Hsueh-Ju Liu, Clark Landis, Christophe Raynaud, Odile Eisenstein, T. Don Tilley
Masked silylene complexes Cp*­(IXy-H)­(H)­RuSiH2R (R = Mes (3) and Trip (4); IXy = 1,3-bis­(2,6-dimethylphenyl)­imidazol-2-ylidene; “IXy-H” is the deprotonated form of IXy) exhibit metallosilylene-like (LnM–Si–R) reactivity, as observed in reactions of nonenolizable ketones, enones, and tosyl azides, to give unprecedented silaoxiranyl, oxasilacyclopentenyl, and silaiminyl complexes, respectively. Notably, these silicon-containing complexes are derived from the primary silanes MesSiH3 and TripSiH3 via activation of all three Si–H bonds. DFT calculations suggest that the mechanism of formation for the silaoxiranyl complex Cp*­(IXy)­(H)2Ru–Si­(OCPh2)­Trip (6) involves coordination of benzophenone to a silylene silicon atom, followed by a single-electron transfer in which Si-bonded, non-innocent benzophenone accepts an electron from the reactive, electron-rich ruthenium center. Importantly, this electron transfer promotes an unusual 1,2-hydrogen migration to the resulting, more electron-deficient ruthenium center via a diradicaloid transition state.