Amphoteric Allenylidene Ruthenium Complexes and the First Dinuclear Ruthenium Species with a Bis-alkenyl Carbyne Bridging Ligand

Cationic ruthenium(II) allenylidenes trans-[Cl(dppe)2RuCCC(CH3)R]BF4 (R = Ph, CH3) can be deprotonated to generate neutral alkenyl acetylide metal trans-[Cl(dppe)2Ru−C⋮C−C(CH2)R] or protonated with HBF4·Et2O to lead to dicationic ruthenium(II) carbynes trans-[Cl(dppe)2Ru⋮C−CHC(CH3)R](BF4)2. The latter reaction was applied to transform a conjugated bis-allenylidene bridged diruthenium complex, trans-[Cl(dppe)2RuCCC(CH3)-p-C6H4−(CH3)CCCRu(dppe)2Cl](BF4)2, into the first bis-alkenyl carbyne ruthenium species trans-[Cl(dppe)2Ru⋮C−CHC(CH3)-p-C6H4−(CH3)CHC−C⋮Ru(dppe)2Cl](BF4)4.