Further reactions of some bis(vinylidene)diruthenium complexes

Abstract

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 KOBut. 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). © 2004 Elsevier B.V. All rights reserved.