SELECTIVE SYNTHESIS OF INDENYLRUTHENIUM(II) VINYLVINYLIDENE COMPLEXESVIA UNSTABLE ALLENYLIDENE INTERMEDIATES - UNEXPECTED FORMATION OF ALKENYL-PHOSPHONIO COMPLEXES (E)-[RU(C(H)=C(PPH3)R)(ETA(5)-C9H7)(PPH3)(2)][PF6] (R=1-CYCLOHEXENYL, 1-CYCLOHEPTENYL) THROUGH NUCLEOPHILIC-ADDITION OF TRIPHENYLPHOSPHINE ON VINYLVINYLIDENE DERIVATIVES

The vinylvinylidene complexes u{=C=C(H)C=CHCH2(CH2)(n)CH2}(eta(5)-C9H7 )L-2][PF6] (L = PPh3, L-2 = 1,2-bis(diphenylphosphino)ethane (dppe); n = 1 (2a,b), 2 (3a,b), 3 (4a,b)) have been prepared by reaction of [Ru Cl(eta(5)-C9H7)L-2] with 1-ethynyl-1-cycloalkanols and NaPF6 in reflux ing methanol. Deprotonation of the vinylidene derivatives with Al2O3 y ields the neutral enynyl complexes [Ru{C=CC=CHCH2(CH2)(n)CH2}(eta(5)-C 9H7)L-2] (5a,b, 6a,b, and 7a,b). The reaction of the enynyl complex [R u(C=CR)(eta(5)-C9H7)(PPh3)(2)] (R = 1-cyclohexenyl; 6a) with MeOSO2CF3 produces the disubstituted vinylvinylidene derivative [Ru{=C=C(Me)R}( eta(5)-C9H7)(PPh3)(2)][CF3SO3] (R = 1-cyclohexenyl; 8a). The crystal s tructure of 8a was determined by X-ray diffraction methods, In the str ucture the Ru=C=C chain is nearly linear (Ru-C(1)-C(2) = 176.2(4)degre es) with an Ru-C(1) distance of 1.838(5) Angstrom. The indenyl ligand is eta(5)-bonded to the metal with the benzo ring orientated ''trans'' with respect to the vinylidene group. When the reaction of [RuCl(eta( 5)-C9H7)(PPh3)(2)] with 1-ethynylcyclohexanol or 1-ethynylcyclopentano l and NaPF6 takes place in the presence of PPh3, the alkynylphosphonio complexes Ph3)CH2CH2(CH2)(n)CH2}(eta(5)-C9H7)(PPh3)(2)][PF6] (n = 1 ( 11a), 2 (12a)) were obtained via nucleophilic attack, of the PPh3 on C -gamma of the unstable allenylidene complexes H2CH2(CH2)(n)CH2}(eta(5) -(CH7)-H-9)(PPh3)(2)][PF6] (n = 1 (9a), 2 (10a)). The vinylvinylidene complexes 3a (n = 2) and 4a (n = 3) also react with PPh3, giving the a lkenyl-phosphonio complexes (E)-[Ru{C(H)=C(PPh3)C=CHCH2(CH2)(n)CH2}(et a 5-C9H7)(PPh3)(2)][PF6] (n = 2 (13a), 3 (14a)). The structure of 13a was confirmed by X-ray diffraction methods. A possible mechanism for t he formation of 13a and 14a is proposed.