Ruthenium complexes containing butatrienylidene and related ligands: synthesis, characterisation and chemistry

The reaction of buta-1,3-diyne with [Ru(thf)(PPh3)(2)(eta-C5H5)](+) (thf = tetrahydrofuran) to give [Ru(C=C=C=CH2)(PPh3)(2)(eta-C5H5)](+) has been studied. This complex adds nucleophiles at C-gamma, as expected from theory and consideration of the protection afforded to C-alpha by the bulky PPh3 ligands. The products were alkenylethynyl complexes (from aprotic nucleophiles) or methylallenylidene complexes (from protic nucleophiles, with H migration to C-delta). With water, the complex [Ru{C=CC(O)Me}(PPh3)(2)(eta-C5H5)] is formed. The single-crystal structures of [Ru{C=C=CMe(X)}(PPh3)(2)(eta-C5H5)][PF6] (X = NPh2 or C4H3NMe-2) and[Ru(C=CCH=CHCl-trans)(PPh3)(2)(eta-C5H5)] have been determined.