Further reactions of some bis(vinylidene)diruthenium complexes

Whereas {Ru(dppm)Cp*}2(μ-Ctriple bond; length of mdashCCtriple bond; length of mdashC) (2) is the only product formed by deprotonation of [{Ru(dppm)Cp*}2{μ(double bond; length as m-dashCdouble bond; length as m-dashCHCHdouble bond; length as m-dashCdouble bond; length as m-dash)}]+ with dbu, a mixture of 2 with Ru{Ctriple bond; length of mdashCCHdouble bond; length as m-dashCH(PPh2)2[RuCp*]}(dppm)Cp* (3) and {Cp*Ru(PPh2CHCdouble bond; length as m-dashCH–)}2 (4) is obtained with KOBut. A similar reaction with [{Ru(dppm)Cp*}2{μ(double bond; length as m-dashCdouble bond; length as m-dashCMeCMedouble bond; length as m-dashCdouble bond; length as m-dash)}]+ (5) gave Ru{Ctriple bond; length of mdashCCMedouble bond; length as m-dashCH(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-Ctriple bond; length of mdashCCtriple bond; length of mdashC) (8-Ru) regenerates its precursor [{Ru(dppe)Cp*}2{μ(double bond; length as m-dashCdouble bond; length as m-dashCHCHdouble bond; length as m-dashCdouble bond; length as m-dash)}]2+ (7-Ru). Ready oxidation of the bis(vinylidene) complex affords the cationic carbonyl [Ru(CO)(dppe)Cp*]PF6 (9) (X-ray structure).