Intermolecular activation of carbon-hydrogen bonds has been accomplished by reduction with sodium amalgam of (sip3)(Me3P)RuCl2, 1, [“sip3” = MeSi(CH2PMe)2)3] in aromatic hydrocarbons, such as benzene and substituted derivatives thereof. In these reactions, the 16e equivalent (sip3XMe3P)Ru(O) thus generated exhibits a preference for insertion across the unhindered metaand para-C-H bonds to produce complexes of composition (sip3)(Me3P)RuH(C6H3RR′) [R = R′ = H, 2; R = H, R′ = CH3, 3; R = R′ = CH3 (3,4-xylyl), 4; R = R′ = CH3 (3,5-xylyl), 5; R = H, R′ = CF3, 6], of which 3, 4, and 6 were isolated as mixtures of meta/para-isomers and Ru-aryl rotamers, respectively. Reaction of the phenyl hydride 2 with 4-MeC6H4NCE (E = O, S) leads to insertion of the heteroallenes into the Ru-Η bond to give (sip3)(Me3P)Ru[N(C6H4Me-4)C(O)H]C6H5, 8, and (sip3)(Me3P)Ru[SC(=NC6H4Me-4)H]C6H5, 10, as the primary products. While the latter forms (sip3), 11, by loss of PMe3, the former reacts with another molecule of isocyanate to afford the acyl compound (sip3)9, as the ultimate product. Treatment of 2 with CO2 results in the formation of a carbonato derivative, (sip3)(Me3P)Ru(O2CO), 7.•