Regioselective nucleophilic additions on indenyl-ruthenium(II)-allenylidene complexes. X-ray crystal structure of the alkynyl complex [Ru{C CC(C CH)Ph-2}(eta(5)-C9H7)(PPh3)(2)]

The diphenylallenylidene complexes [Ru=C=C=CPh2)(eta(5)-C9H7)L-2][PF6](L = PPh3; L-2 = 1,2-bis(diphenylphosphino)ethane (dppe), bis(diphenylphosphino)methane (dppm)) (1a-c) react with NaOMe to yield the methoxyalkynyl derivatives [Ru{C=CC(OMe)Ph-2}(eta(5)-C9H7)L-2] (3a-c). Protonation of these species gives back the starting allenylidene derivatives. Regioselective additions on the C-gamma are also observed when 1a,b are treated with LiR (R = Me, Bu-n), giving the alkynyl complexes [Ru{C=CC(R)Ph-2}(eta(5)-C9H7)L-2] (4a,b, 5a,b). Vinylidene derivatives [Ru{=C=C(H)C(R)Ph-2}(eta(5)-C9H7)(PPh3)(2)][BF4] (6a, 7a) can be prepared by protonation of complexes 4a and 5a with HBF4. The diphenylallenylidene compound 1c reacts with (LiBu)-Bu-t to yield the metallacycle complex [Ru{(kappa 3(C,P,P). C=C=CPh2(Ph2PCHPPh2)}(eta(5)-C9H7)] (8c). The alkynyl complexes [Ru(C=CC(C=CR)Ph-2}(eta(5)-C9H7)(PPh3)(2)] (R = Ph, Pr-n, H) (9a-11a) have been obtained by reaction of 1a with lithium or sodium acetylides. Protonation of these derivatives yields the vinylidene complexes [Ru{=C=C(H)C(C=CR)Ph-2}(eta(5)-C9H7)(PPh3)(2)][BF4] (12a-14a). The crystal structure of [Ru(C=CC(C=CH)Ph-2}(eta(5)C(9)H(7))(PPh3)(2)] (11a) was determined by X-ray diffraction methods. In the structure the alkynyl chain is nearly linear (Ru-C(1)-C(2) = 175.0(2)degrees) with Ru-C(1) and C(1)-C(2) distances of 1.993(2) and 1.209(3) Angstrom, respectively. The monosubstituted allenylidene complex [Ru{=C=C=C(H)Ph}(eta(5)-C9H7)(PPh3)(2)]]PF6] (2a) reacts with PMe3, PMe2Ph, PMePh2, and PPh3 to yield the cationic alkynyl-phosphonio derivatives [Ru{C=CC(PR3)(H)Ph}(eta(5)-C9H7)(PPh3)(2)][PF6] (17a-20a) in a regioselective way. Similarly, allenylidene complexes 1a-c add PMe3 to give the corresponding alkynyl-phosphonio derivatives 15a-c. [Ru{C=CC(PMe3)Ph-2}(eta(5)-C9H7)(dppm)][PF6] (15c) undergoes an isomerization process to yield the thermo dynamic ally more stable allenyl-phosphonio complex [Ru{C(PMe3)=C=CPh2}(eta(5) C9H7) (dppm)][PF6] (21c), [Ru{C(PMe2Ph)=C=CPh2}(eta(5)-C9H7)(dppm)][PF6] (22c) can be obtained directly by addition of PMe2Ph to the C-alpha atom of 1c. The behavior of the diphenylallenylidene complexes 1a-c toward sodium 2-methylthiophenolate is also discussed.