Solvent-Assisted Reversible Proton Transfer within an Intermolecular Dihydrogen Bond and Characterization of an Unstable Dihydrogen Complex

Abstract

A reversible protonation of transition metal hydrides by weak proton donors has been found by NMR spectroscopy. The reactants are mixed at room temperature, but the protonation is induced only at low temperature by an increase of the dielectric constant of a suitably chosen solvent. Under these conditions the decomposition via dihydrogen release is avoided. Thus, the unstable complex [Cp*RuH4(PCy3)]+ was obtained in CDF3/CDF2Cl by protonation of Cp*RuH3(PCy3) with fluorinated alcohols.