Ru-5(mu(5)-C)(CO)(15), 1, has been found to activate CH bonds in the vinyl group of polar vinyl olefins, methyl acrylate (MA), and vinyl acetate (VAc), through a cluster opening process to yield the complexes Ru-5(mu(5)-C)(CO)(14)[eta(2)-O= C(OMe)CH=CH](mu-H), 2, and Ru-5(mu(5)-C)(CO)(14) [eta(2)-(MeCO2)C=CH2](mu-H), 4, respectively. The site of CH activation is dependent on the olefin substituent. In 2, the site of CH activation is the beta-carbon atom of the vinyl group, while in 4 the CH activation has occurred exclusively at the alpha-carbon atom of the vinyl group. Compound 2 can be further decarbonylated to yield the complex Ru-5(mu(5)-C)(CO)(13)[mu-eta(3)-O=C(OMe)CHCH] (mu-H), 3, which contains a eta(3)-bridging acryloyl ligand. Compound 2 reacts with ethylene in the presence of Me3NO to yield three new Ru-5 products: Ru-5(mu(5)-C)(CO)(13)[eta(4)-1-anti,3-syn-{O= C(OMe)}C(H)C(H)C(H)Me](mu-H), 5, Ru-5(mu(5)-C)(CO)(12)(C2H4)[mu-eta(3)-O=C(OMe)C(H)C(H)](mu-H), 6, and Ru-5(mu(5)-C)(CO)(13) [eta(4)-anti-O=C(OMe)H2CHCHCH2](mu-H), 7. Compounds 5 and 7 are isomers containing substituted eta(3)-allyl ligands formed by the coupling of the ethylene to the CH-activated beta-carbon atom of the acryloyl ligand accompanied by some metal-mediated H-shifts. Compound 6 contains an uncoupled pi-coordinated ethylene ligand. Compound 7 was isomerized to 5 thermally at 80 degrees C. Compound 4 reacts with ethylene in the presence of Me3NO to yield two new Ru-5 products: Ru-5(mu(5)-C)(CO)(13) [eta(4)-1,1-anti-syn-[(O2CMe)C(Me)CHCH2](mu-H), 8, and Ru-5(mu(5)-C)(CO)(13) [eta(4)-1-anti-CH(Me)C(O2CMe)(CH2)]-(mu-H), 9. Compounds 8 and 9 both contain substituted eta(3)-allyl ligands formed by the coupling of the ethylene to the CH-activated alpha-carbon atom of the vinyl acetyl ligand. Compound 8 was isomerized to 9 thermally at 80 degrees C. All new products were characterized structurally by single-crystal X-ray diffraction analyses.