Preparation and reactions of some neutral pentamethylcyclopentadienylruthenium vinylidene complexes

A synthesis of neutral vinylideneruthenium complexes [RuCl(C=CHR)(PPh3)(eta-C5Me5)] (R = Ph, Bu-t or SiMe3) from [RuCl(PPh3)(2)(eta-C5Me5)] and 1-alkynes has been developed. This takes advantage of the presence of two bulky ligands (PPh3 and C5Me5), which results in displacement of one PPh3 ligand (rather than chloride) and concomitant isomerisation of the 1-alkyne to vinylidene ligands. The vinylidene complexes undergo facile loss of HCl on treatment with NaOMe in the presence of a 2e donor ligand (L) to give the neutral acetylide complexes [Ru(C=CR)L(PPh3)(eta-C5Me5)] [R = Ph, L = PPh3, CO, O-2 or dppm-P; R = Bu-t, L = PPh3, CO, C2H4, dppe-P, C-2(PPh2)(2)-P, S-2, P(OMe)(3) or AsPh3]; the complexes [Ru(C=CBut)(L-2)(eta-C5Me5)] [L-2 = dppm or PPh2CH= CHPPh2] and [Ru(S2CC=CBut)(PPh3)(eta-C5Me5)] were also obtained. Crystal structure determinations were carried out on eleven of the complexes.