Abstract: | Reactions between Ru(thf)(PPh3)2(η-C5H5)]+ and lithium acetylides have given further examples of substituted ethynylruthenium complexes that are useful precursors of allenylidene and cumulenylidene derivatives. From Li2C4, mono- and bi-nuclear ruthenium complexes were obtained: single-crystal X-ray studies have characterised two rotamers of {Ru(PPh3)2(η-C5H5)}2(μ-C4), which differ in the relative cis and trans orientations of the RuLn groups. Protonation of Ru(CCCCH)(PPh3)2(η-C5H5) afforded the butatrienylidene cation Ru(C=C=C=CH2)(PPh3)2(η-C5H5)]+, which reacted readily with atmospheric moisture to give the acetylethynyl complex Ru{CCC(O)Me}(PPh3)2(η-C5H5), also fully characterised by an X-ray structural study. |