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(diphenyl phosphino)methane (dppm)) (1a-c) react with NaOMe to yield the methoxy alkynyl derivatives [Ru{C=CC(OMe)Ph-2}(eta(5)-C9H7)L-2] (3a-c). Proton ation of these species gives back the starting allenylidene derivative s. 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 [R u{=C=C(H)C(R)Ph-2}(eta(5)-C9H7)(PPh3)(2)][BF4] (6a, 7a) can be prepare d by protonation of complexes 4a and 5a with HBF4. The diphenylallenyl idene compound 1c reacts with (LiBu)-Bu-t to yield the metallacycle co mplex [Ru{(kappa 3(C,P,P). C=C=CPh2(Ph2PCHPPh2)}(eta(5)-C9H7)] (8c). T he alkynyl complexes [Ru(C=CC(C=CR)Ph-2}(eta(5)-C9H7)(PPh3)(2)] (R = P h, Pr-n, H) (9a-11a) have been obtained by reaction of 1a with lithium or sodium acetylides. Protonation of these derivatives yields the vin ylidene 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 s tructure the alkynyl chain is nearly linear (Ru-C(1)-C(2) = 175.0(2)de grees) with Ru-C(1) and C(1)-C(2) distances of 1.993(2) and 1.209(3) A ngstrom, 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 regiose lective way. Similarly, allenylidene complexes 1a-c add PMe3 to give t he corresponding alkynyl-phosphonio derivatives 15a-c. [Ru{C=CC(PMe3)P h-2}(eta(5)-C9H7)(dppm)][PF6] (15c) undergoes an isomerization process to yield the thermo dynamic ally more stable allenyl-phosphonio compl ex [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 add ition of PMe2Ph to the C-alpha atom of 1c. The behavior of the dipheny lallenylidene complexes 1a-c toward sodium 2-methylthiophenolate is al so discussed.