Self-Activation of a Cluster-Bound Alkyne toward Carbon−Carbon Bond Forming Reactions Soa Rivomanana Carole Mongin Guy Lavigne 10.1021/om950835w.s001 https://acs.figshare.com/articles/journal_contribution/Self-Activation_of_a_Cluster-Bound_Alkyne_toward_Carbon_Carbon_Bond_Forming_Reactions/3776751 The methanol-catalyzed elimination of Cl<sup>-</sup> from the “activated” anionic species [PPN][Ru<sub>3</sub>(μ-Cl)(μ-PhCCPh)(CO)<sub>9</sub>] (<b>1</b>) 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, Ru<sub>3</sub>(μ-PhCCPh)(CO)<sub>7</sub>(dppm) (<b>2</b>), or its 48-e CO adduct, Ru<sub>3</sub>(μ-PhCCPh)(CO)<sub>8</sub>(dppm) (<b>3</b>). Whereas the CO-induced conversion of <b>2</b> into <b>3</b> 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 <b>2</b> is reported, revealing a perpendicular conformation of the alkyne relative to the metal triangle. The high reactivity of <b>2</b> 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, Ru<sub>3</sub>(μ-PhCCPh)(CO)<sub>6</sub>(dppm)<sub>2</sub> (<b>4</b>) (53% yield). Reaction of <b>2</b> with hydrogen gas (1 atm, 25 °C, 10 min) yields the dihydrido species, Ru<sub>3</sub>(μ-H)<sub>2</sub>(μ-PhCCPh)(CO)<sub>7</sub>(dppm) (<b>5</b>) (89% yield) existing as a mixture of two isomers differing in the orientation of the alkyne relative to the edge-bridging dppm ligand. Complex <b>2</b> reacts with a terminal alkyne like phenylacetylene under mild conditions to afford a mixture of the “fly-over” type compound Ru<sub>3</sub>{μ-HCC(Ph)C(O)(Ph)CCPh}(dppm)(CO)<sub>6</sub> (<b>6</b>) (57% yield) and the diruthenacyclopentadiene derivative Ru<sub>2</sub>{μ-HCC(Ph)(Ph)CCPh}(μ-dppm)(CO)<sub>4</sub> (<b>7</b>) (20% yield). The structure of <b>6</b> reveals the occurrence of a disymmetric edge-bridging dialkenyl ketone ligand HCC(Ph)C(O)(Ph)CCPh, resulting from regioselective coupling between the two alkynes and a carbonyl group. The formal unsaturation of <b>6</b> 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 <b>6</b>. 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, Ru<sub>3</sub>(μ-H){μ-CC(Ph)C(O)(Ph)CCPh}(dppm)(CO)<sub>6</sub> (<b>8</b>) (94% yield). The X-ray structure of <b>8</b> is reported. Unsuccessful attempts to release the organic moiety from the cluster core are described. The reaction of a THF solution of <b>6</b> with CO in a reactor [<i>P</i>(CO) = 10 atm, <i>T</i> = 80 °C] leads to the new binuclear “fly-over” species Ru<sub>2</sub>{μ-HCC(Ph)C(O)(Ph)CCPh}(CO)<sub>6</sub> (<b>9a</b>), 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 Ru<sub>2</sub>{μ-HCC(C<sub>3</sub>H<sub>7</sub>)C(O)(Ph)CCPh}(CO)<sub>6</sub> (<b>9b</b>) (resulting from the coupling between diphenylacetylene and 1-pentyne) is reported. 1996-02-20 00:00:00 Ru metal triangle Unsuccessful attempts chemical reactivity dppm THF solution carbonyl group 10 min vinylidene alkenyl ketone HC cluster core dihydrido species 9 b PhCCPh HCC Complex 2 1 atm 3 h CO 1 equiv terminal alkyne 1 h CH activation 10 atm PPN metal centers cluster fragmentation alkenyl end Facile loss