A cationic allenylideneruthenium(II) complex with two bulky hemilabile phosphine ligands

The allenylidene complex [RuCl(=C=C=CPh2,)(kappa (2)-P,O- Cy2PCH2CH2OCH3)(2 )]PF6 (2) has been prepared from [RUCl2(kappa (2)-P,O-Cy2PCH2CH2OCH3)(2)] ( 1) and HC=C-C(OH)Ph-2 in the presence of AgPF6. Protonation of 2 with HBF4 in diethyl ether leads to the formation of the dicationic ruthenium carbyne [RuCl(=CCH=CPh2)(kappa (2)-P,O-Cy2PCH2CH2OCH3)(kappa -P-Cy2PCH2CH2OCH3)](2 +), which is catalytically less active in olefin metathesis than related sp ecies with RuHCl(=CCH3) as a molecular unit. The molecular structure of 2 h as been determined by X-ray crystallography.