The methanol-catalyzed elimination of Cl- from the “activated” anionic species [PPN][Ru3(μ-Cl)(μ-PhCCPh)(CO)9] (1) in the presence of bis(diphenylphosphino)methane (dppm) constitutes a rational high-yield route (>90%) to either the unique unsaturated 46-e (alkyne)triruthenium cluster, Ru3(μ-PhCCPh)(CO)7(dppm) (2), or its 48-e CO adduct, Ru3(μ-PhCCPh)(CO)8(dppm) (3). Whereas the CO-induced conversion of 2 into 3 is complete within few seconds at 25 °C under 1 atm of CO, the reverse transformation takes 1 h at 80 °C. The X-ray structure analysis of 2 is reported, revealing a perpendicular conformation of the alkyne relative to the metal triangle. The high reactivity of 2 is substantiated by a high chemical reactivity toward 2-e donors. Its reaction with 1 equiv of dppm (25 °C, 3 h) leads to the bis-dppm-substituted complex, Ru3(μ-PhCCPh)(CO)6(dppm)2 (4) (53% yield). Reaction of 2 with hydrogen gas (1 atm, 25 °C, 10 min) yields the dihydrido species, Ru3(μ-H)2(μ-PhCCPh)(CO)7(dppm) (5) (89% yield) existing as a mixture of two isomers differing in the orientation of the alkyne relative to the edge-bridging dppm ligand. Complex 2 reacts with a terminal alkyne like phenylacetylene under mild conditions to afford a mixture of the “fly-over” type compound Ru3{μ-HCC(Ph)C(O)(Ph)CCPh}(dppm)(CO)6 (6) (57% yield) and the diruthenacyclopentadiene derivative Ru2{μ-HCC(Ph)(Ph)CCPh}(μ-dppm)(CO)4 (7) (20% yield). The structure of 6 reveals the occurrence of a disymmetric edge-bridging dialkenyl ketone ligand HCC(Ph)C(O)(Ph)CCPh, resulting from regioselective coupling between the two alkynes and a carbonyl group. The formal unsaturation of 6 is masked by a weak interaction between the terminal C−Ph bond of the organic chain and one of the metal centers. Facile loss of this interaction is induced by mild thermolysis of 6. As a consequence, free rotation of the organic moiety around the metal−metal edge brings the opposite end of the organic chain (i.e., the C−H bond) close to the opposite face, thereby favoring CH activation to convert the alkenyl end into a vinylidene. This leads to quantitative formation of the vinylidene alkenyl ketone derivative, Ru3(μ-H){μ-CC(Ph)C(O)(Ph)CCPh}(dppm)(CO)6 (8) (94% yield). The X-ray structure of 8 is reported. Unsuccessful attempts to release the organic moiety from the cluster core are described. The reaction of a THF solution of 6 with CO in a reactor [P(CO) = 10 atm, T = 80 °C] leads to the new binuclear “fly-over” species Ru2{μ-HCC(Ph)C(O)(Ph)CCPh}(CO)6 (9a), thereby indicating that elimination of the edge-bridging dppm and cluster fragmentation are more favorable than elimination of a free ketone from the intact cluster. The X-ray structure of Ru2{μ-HCC(C3H7)C(O)(Ph)CCPh}(CO)6 (9b) (resulting from the coupling between diphenylacetylene and 1-pentyne) is reported.
2285W.M. and I.S.) are acknowledged for financial support. We are grateful to Dr, R. Pichon (&e&) for ~~~~ in NMR experiments.Supplementary Material Available: For 17 and 8 tables of hydrogen atom "meters and anisotrodc vibrational Da-from a difference synthesis. The orientation of the methyl group was also established from a difference synthesis. Full-matrix at R = 0.040 and R, = 0.039. In the final difference synthesis lap( values were leas than 0.60 eA-3. Final atomic coordinates are listed in Table V. least.sqq~are~ refinement of 311 parameters converged (AI0 < 0.06) -rameters and complete geometry listings (lo pages); listings of observed and calculated structure factors (18 pages). Ordering information is given on any current masthead page. Acknowledgment. Among the three halidepromoted complexes [PPN] [RU&C~)(CO)~~I ([PPNI [ll), [PPNI [ R U~~~-C~) ( C O )~~] ([PPN][2]), and [PPN][RU~(~&~)(CO)~] ([PPN][3]) (the last complex is observed here for the first time), which are readily obtained by addition of [PPN] [Cl] (PPN = bis(triphenylphophorany1idene)a"onium) to RU&CO)~~, the complexes [PPN][2] and [PPN][3] react with alkynes ((a) acetylene, (b) phenylacetylene, (c) diphenylacetylene, (d) dimethylacetylene) to produce the activated species [PPN] [Ru3(p-C1)(p3-y2-RCCR')(CO)g] ([PPN][4]; THF, 25 OC, 10 min, 100% spectroscopic yield), in which the halide behaves as a good leaving group whose displacement can be catalyzed by a protic solvent. The scope of this synthetic procedure is examined. (LPPNI [4cl) has been crystallized in 87% yield, and its X-ray structure is reported. Crystal data: triclinic, Pl (No. 21, a = 15.913 (4) A, b = 16.307 (4) A, c = 10.992 (4) A, a = 82.73 (2)O, j 3 = 98.55 (3)O, y = 103.21 (4)O, V = 2733 A3, 2 = 2, p(Mo Ka) = 9.65 cm-l; Enraf-Nonius CAD4 diffractometer; final R, = 0.046 and R = 0.045 (from 6490 observations and 340 variables). The structure consists of an open triruthenium cluster unit where the alkyne ligand is coordinated in a p3-q2-II fashion. The bridging halide spans the open edge of the metal triangle and is slightly shifted below this plane. The reactivity of [PPN][4b-d] has been investigated. Protonation of the anion [4c]-at -78 OC gives the corresponding neutral hydrido complex Ru,(?-H)(p-C1)(ps-r12-(CeHa)CC(CeHs))(CO)g (54. The complex [PPN] [4d] reacts with CO at 25 OC in dichloromethanelmethanol solution to yield Ru3(p3-r12-CH3CCCH3)(p-CO)(C0)g (6d) selectively. This complex can be isolated in pure form by extraction from a biphasic methanollhexane mixture, a procedure avoiding chromatographic workup (yield, crystallized, 60%). Its X-ra structure is reported. Crystal data for 6 d monoclinic, R 1 / c (No. 14), a = 14.716 (1) A, b = 14.153 (2) l, c = 18.226 (2) A, B = 96.70 (2)O, V = 3770 A3, 2 = 8 (two independent cluster molecules in the asymmetric unit); final R = 0.030 and R, = 0.037 (from 6362 observations and 523 variables). The alkyne is coordinated in a p3-v2-II mode, and there is one bridging carbonyl spanning the metal-metal edge pardel to the alkyne. ...
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