Activation of Alkynols by Half-Sandwich Ruthenium Complexes: Isolation of Hydroxyalkynyl(hydrido) and Hydroxyvinylidene Derivatives

The complex [Cp*RuCl(PEt 3 ) 2 ] (Cp* = C 5 Me 5 ) reacts with 2-propyn-1-ol derivatives, HC⋮CC(OH)RR‘ (R = R‘= H; R = R‘ = CH 3; R = CH 3, R‘ = Ph), in MeOH in the presence of NaBPh 4 yielding the metastable 3-hydroxyalkynyl hydrido complexes [Cp*Ru(H)(C⋮CC(OH)RR‘)(PEt 3 ) 2 ][BPh 4 ], intermediates in the formation of the corresponding 3-hydroxyvinylidene complexes, to which these compounds rearrange both in solution and in the solid state.