Further reactions of some bis(vinylidene)diruthenium complexes

Article abstract of DOI:10.1016/j.jorganchem.2004.09.084

Whereas {Ru(dppm)Cp*}₂(μ-C≡CC≡C) (2) is the only product formed by deprotonation of [{Ru(dppm)Cp*} ₂-{μ(=C=CHCH=C=)}]⁺ with dbu, a mixture of 2 with Ru{C≡CCH=CH(PPh₂)₂[RuCp*]}(dppm)Cp* (3) and {Cp*Ru(PPh₂-CHC=CH-)}₂ (4) is obtained with KOBu^t. A similar reaction with [{Ru(dppm)Cp*} ₂{μ(=C=CMeCMe=C=)}]⁺ (5) gave Ru{C≡CCMe= CH(PPh₂)₂[RuCp*]}(dppm)Cp* (6). X-ray structures of 4, 5 and 6 confirm the presence of the 1-ruthena-2,4- diphosphabicyclo[1.1.1]pentane moiety, which is likely formed by an intramolecular attack of the deprotonated dppm ligand on C(1) of the vinylidene ligand. Protonation of {Ru(dppe)Cp*}₂(μ-C≡CC≡C) (8-Ru) regenerates its precursor [{Ru(dppe)Cp*}₂-{μ(=C=CHCH= C=)}]²⁺ (7-Ru). Ready oxidation of the bis(vinylidene) complex affords the cationic carbonyl [Ru(CO)(dppe)Cp*]PF₆ (9) (X-ray structure).