Electron Hydrido dihydrogen Complexes, Proton Transfer and C-H Activation

5 18-Electron Hydrido(dihydrogen) Complexes, Proton Transfer and C-H Activation 

Addition of proton donors to [RuH2(H2)2(PCy3)2] gives, after substitution of the two dihydrogen ligands, new hydrido(dihydrogen) derivatives, as is the case with carboxylic acids  

Similar reactions were carried out with various good a-donors which are also proton donors such as hydroxo-, amino- or thio-pyridine or quinoline (HE-L) thus producing a new series of complexes [RuH(H2)(E-L)(PCy3)2] in which, because of the high electron density induced by the presence of these ligands, a significant vibrational mode of the H-H bond is observed in the IR 

Spectrum. In addition, an H-H distance of ca. 1.3 A was calculated for [RuH(H2)(OC5H4N)(PCy3)2] from the relaxation time of the hydride signal and from the H-D coupling constant observed after partial deuteration of the compound. 

Dihydrogen can be eliminated from 9 to give the 16-electron species [RuH(PPr 3)2(CgH4C5H4N)] or substituted by various small molecules to give [RuH(L)(PPr 3)2(CgH4C5H4N) (L = N2, O2, CO or C2H4). Ethylene can easily be removed from the last complex but no sign of insertion into the Ru-H or Ru-C bonds is observed. 

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