cis-[RuH2(dcpe)2] and cis-[OsH2(dcpe)2] (dcpe = Cy2PCH2CH2PCy2) behave as catalyst precursors for the hydrogenation of C = C bonds in a number of organic substrates. The ruthenium species is the more active one for the reduction of enones to saturated ketones. In contrast, the hydrogenation of unactivated olefins is faster in the presence of the osmium catalyst. Experimental evidence of the formation of the catalytically active species via dissociation of one diphosphine is obtained.
