The allenylidene complexes [M(CCCR2)(η5-C9H7)L2][PF6] (M = Ru, L = PPh3, L2 = 1,2-bis(diphenylphosphino)ethane (dppe), bis(diphenylphosphino)methane (dppm), R2 = 2 Ph (1a−c), C12H8 (2,2‘-biphenyldiyl) (2a−c); M = Os, L = PPh3, R2 = 2Ph (3), C12H8 (4)) have been prepared by reaction of the complexes [MCl(η5-C9H7)L2] with HC⋮CC(OH)R2 and NaPF6 in refluxing methanol. The crystal structures of [M(CCCPh2)(η5-C9H7)(PPh3)2][PF6]·CH2Cl2 (M = Ru (1a), Os (3)) were determined by X-ray diffraction methods. In the structures the MCCC chains are nearly linear (M−C(1)−C(2) = 168.5(5)° (1a) and 169.3(4)° (3); C(1)−C(2)−C(3) = 168.2(7)° (1a) and 168.0(5)° (3)) with MC(1) distances of 1.878(5) Å (1a) and 1.895(4) Å (3). The indenyl ligand is η5-bonded to the metal with the benzo ring orientated “cis” with respect to the allenylidene group. Extended Hückel molecular orbital calculations have been used to rationalize the preferred “cis” orientation. The reaction of [RuCl(η5-C9H7)L2] (L = PPh3, L2 = dppe, dppm) with HC⋮CCMe(OH)Ph and NaPF6 in refluxing methanol leads to the formation of the allenylidene complexes [Ru{CCC(Me)Ph}(η5-C9H7)L2][PF6] (6a−c) along with the vinylvinylidene isomers [Ru{CC(H)C(Ph)CH2}(η5-C9H7)L2][PF6] (L = PPh3 (5a), L2 = dppe (5b), dppm (5c)). Only complex 6a could be isolated by chromatography (SiO2) from these mixtures along with complex 7a obtained from the deprotonation of the vinylvinylidene complex 5a. The treatment of these reaction mixtures with potassium carbonate yields the neutral σ-enynyl derivatives [Ru{C⋮CC(Ph)CH2}(η5-C9H7)L2] (7a−c). The monosubstituted allenylidene complex [Ru{CCC(H)Ph}(η5-C9H7)(PPh3)2][PF6] (9) has been prepared by the reaction of [RuCl(η5-C9H7)(PPh3)2] with HC⋮CCH(OH)Ph and NaPF6 in methanol. Under similar reaction conditions [RuCl(η5-C9H7)L2] reacts with HC⋮CCH(OH)R and NaPF6 to afford the alkenylmethoxycarbene derivatives [Ru{C(OMe)C(H)CH(R)}(η5-C9H7)L2][PF6] (L2 = dppe, R = Ph (11b); L2 = dppm, R = Ph (11c), H (13)). [RuCl(η5-C9H7)(PPh3)2] also reacts with HC⋮CC(OH)H2 to give the hydroxyvinylidene complex [Ru{CCH(CH2OH)}(η5-C9H7)(PPh3)2][PF6] (12), which is stable toward the dehydration process.

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Intramolecular [2 + 2] cycloaddition of two C=C bonds in vinylidene complexes [Ru(eta5-C9H7){=C=C(R)H}(PPh3){kappa1-(P)-PPh2(C3H5)][BF4] affords cyclobutylidene complexes [Ru(eta5-C9H7){kappa2-(P,C)-(=CC(R)HCH2CHCH2PPh2)}(PPh3)][BF4], which can be also obtained by reaction of terminal alkynes with [Ru(eta5-C9H7)(PPh3){kappa3-(P,C,C)-PPh2(C3H5)}][PF6]. The reaction proceeds under mild conditions via vinylidene complexes, and the activation parameters were determined by kinetic studies.

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The treatment of [RuCl 2 (COD)] n with KC 9 H 7 in THF leads to the formation of [Ru(η 5 -C 9 H 7 )Cl(COD)] (1) (80% yield) in a one-pot synthesis. Complex 1 is also formed by the reaction of [RuCl 2 (COD)] n with NaC 9 H 7 in THF followed by treatment of the intermediate complex [Ru(η 5 -C 9 H 7 )(η 2 -η 3 -C 8 H 11 )] (2) with HCl. Substitution of the labile COD ligand by bulky phosphines PR 3 (R ) Cy, i Pr 3 ) can be achieved at room temperature in THF to give 16electron species [Ru(η 5 -C 9 H 7 )Cl(PR 3 )], which react with CO (1 atm) to afford complexes 5) have been similarly prepared by reaction with the bidentate ligands. [Ru(η 5 -C 9 H 7 )Cl(NBD)] (NBD ) norbornadiene) (6) has been prepared through an exchange reaction of 1 with NBD and characterized by X-ray diffraction. Neutral complexes [Ru(η 5 -C 9 H 7 )X-(COD)] (X ) FBF 3 (7), N 3 (8)) were prepared from complex 1 by metathesis reactions of the chloride ligand by AgBF 4 and NaN 3 respectively. The treatment of 7 in CH 2 Cl 2 with an excess of pyridine and acetonitrile gives cationic complexes [Ru(η 5 -C 9 H 7 )(COD)L][BF 4 ] in good yield (L ) py (9), CH 3 CN (10)). The structure of complex 9 has been determined by X-ray diffraction. Complex 1 catalyzes [2+2] and [4+2] cycloaddition reactions of norbornene and 1,5-cyclooctadiene with alkynes to give exotricyclic [4.2.1.0] coupling products and exotricyclo [4.2.2.0]dec-7-enes, respectively. These processes take place with high efficiency and selectivity. Complex 1 is also active in the catalytic hydration of terminal alkynes to afford ketones in high yield and selectivity.