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Reactions of a series of unsymmetrically substituted N-heterocyclic carbene ligands with Ru3(CO)12afforded a variety of mononuclear (1, 2), trinuclear (3, 4, 5, and 5′), and tetranuclear (6, 7) ruthenium complexes via intramolecular ruthenium-mediated sp2and sp3C–H bond activations. Complexes 6and 7include an octahedral cluster skeleton consisting of four ruthenium atoms and two metalated carbon atoms. The formation of this type of ruthenium clusters is proposed to involve the initial C–C double-bond migration and subsequent sp2C–H bond activations. All new complexes were fully characterized, and the molecular structures of 1, 2, 5, 6, and 7were determined by X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

Thermal treatment of dihydrooctamethyl-s-indacene with Ru3(CO)12afforded the trinuclear and tetranuclear complexes Ru3(η5:η5:η2-C20H24)(CO)7(1) and Ru4(η5:η4:η1-C20H24)(μ-CO)2(CO)7(2), via intramolecular sp3C−H bond activation, and the mononuclear complex Ru(η5-C20H25)(CO)2Cl (3), which might be formed via chlorination of a terminal hydride complex during column chromatography. Reaction of 1,2,3,4,7-pentamethylindene with Ru3(CO)12also yielded the tetranuclear complex Ru4(η5:η3:η2-C14H16)(CO)9(4) via the same sp3C−H bond activation, together with the dinuclear complex [(η5-C9H2Me5)Ru(CO)]2(μ-CO)2(5). In contrast, reaction of 4,7-dimethylindene with Ru3(CO)12gave only the dinuclear complex [(η5-C9H5Me2)Ru(CO)]2(μ-CO)2(6). The molecular structures of all six complexes have been determined by single-crystal X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]