An Ru-Substituted Tris(Ethynyl)Methyl Cation: Synthesis, Properties, And Structure Of [{Cp(Dppe)Ru(C;C)}(3)C]Pf6 Center Dot C6h6

The dark blue complex [{Cp(dppe)Ru(C;C)}(3)C]PF6 1 (Cp=cyclopentadienyl, dppe=1,2-bis(diphenylphosphino)ethane) was obtained in 46% yield by treatment of Ru(C;CH)(dppe)Cp with CuCl/TMEDA (tetramethylethanediamine), followed by KOH and [NH4]PF6 in acetone; it was accompanied by known complexes {Cp(dppe)Ru}C;CC;C{Ru(dppe)Cp} 2 (22%) and yellow [1,3-{Cp(dppe)Ru}(2)C4H3]PF6 3 (2.6%). The structure of the cationic fragment of 1 in its benzene solvate consists of a central planar C attached to three C;CRu(dppe)Cp fragments. The cation of 3 consists of a cyclobuten-1,3-diyl group bearing two Ru(dppe)Cp groups. The C-13 NMR resonance of the central C in 1 is found at delta 66.11. The cyclic voltammogram of 1 contains three irreversible oxidation waves at +0.87, +0.79, and +0.25V, together with a reversible reduction wave at -1.38V (versus FeCp2/[FeCp2](+)).