Activation of an aliphatic C-H bond at room temperature. Conversion on a cluster of a stable s-bonded alkyl group to a m2-alkylidene ligand. Synthesis and crystal structure determination of HOs3(6-CH2C5H3N-2-C(H)=N-i-Pr)(CO)9 andH2Os3(6-CH-C5H3N-2-C(H)=N-i-Pr)(CO)8