10.1021/om801119t.s003 Stephan Beer Stephan Beer Kai Brandhorst Kai Brandhorst Cristian G. Hrib Cristian G. Hrib Xian Wu Xian Wu Birte Haberlag Birte Haberlag Jörg Grunenberg Jörg Grunenberg Peter G. Jones Peter G. Jones Matthias Tamm Matthias Tamm Experimental and Theoretical Investigations of Catalytic Alkyne Cross-Metathesis with Imidazolin-2-iminato Tungsten Alkylidyne Complexes American Chemical Society 2009 dinuclear tungsten alkylidyne 3CC OC ligand CMe 3LYP DFT 5 b Li complex 11. Complex 5 2009-03-09 00:00:00 Dataset https://acs.figshare.com/articles/dataset/Experimental_and_Theoretical_Investigations_of_Catalytic_Alkyne_Cross_Metathesis_with_Imidazolin_2_iminato_Tungsten_Alkylidyne_Complexes/2872951 The imidazolin-2-iminato tungsten alkylidyne complexes [Me<sub>3</sub>CC≡W(NIm<sup>R</sup>)(OR′)<sub>2</sub>] (<b>4a:</b> R = <i>t</i>Bu, R′ = CMe<sub>3</sub>; <b>4b:</b> R = Dipp, R′ = CMe<sub>3</sub>; <b>5a:</b> R = <i>t</i>Bu, R′ = CMe(CF<sub>3</sub>)<sub>2</sub>; <b>5b:</b> R = Dipp, R′ = CMe(CF<sub>3</sub>)<sub>2</sub> have been prepared from [Me<sub>3</sub>CC≡W(OCMe<sub>3</sub>)<sub>3</sub>] (<b>2</b>) and [Me<sub>3</sub>CC≡W{OCMe(CF<sub>3</sub>)<sub>2</sub>}<sub>3</sub>(dme)] (<b>3</b>, dme = 1,2-dimethoxyethane) by reaction with the lithium reagents Li(NIm<sup><i>t</i>Bu</sup>) and Li(NIm<sup>Dipp</sup>), generated with MeLi from 1,3-di-<i>tert</i>-butylimidazolin-2-imine (Im<sup><i>t</i>Bu</sup>NH) or 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-imine (Im<sup>Dipp</sup>NH), respectively. Reaction of <b>3</b> with Li[N(<i>t</i>Bu)Ar]·OEt<sub>2</sub> (Ar = 3,5-dimethylphenyl) afforded the amido complex [Me<sub>3</sub>CC≡W{N(<i>t</i>Bu)Ar}{OCMe(CF<sub>3</sub>)<sub>2</sub>}<sub>2</sub>] (<b>6</b>). Addition of Li[OCPh(CF<sub>3</sub>)<sub>2</sub>] to [Me<sub>3</sub>CC≡WCl<sub>3</sub>(dme)] (<b>1</b>) produced the dme-free complex [Me<sub>3</sub>CC≡W{OCPh(CF<sub>3</sub>)<sub>2</sub>}<sub>3</sub>] (<b>7</b>), which, upon treatment with Li(NIm<sup><i>t</i>Bu</sup>), gave the alkylidene complex <b>8</b>, presumably formed by activation and addition of an <i>ortho</i>-C−H bond across the W≡C bond in the intermediate alkylidyne complex. Treatment of <b>1</b> with Li[OC(CF<sub>3</sub>)<sub>3</sub>] led to the substitution of only two chloride ligands and formation of <i>cis-</i>[Me<sub>3</sub>CC≡WCl{OC(CF<sub>3</sub>)<sub>3</sub>}<sub>2</sub>(dme)] (<b>9</b>), which exhibits long-range through-space <sup>19</sup>F−<sup>19</sup>F coupling between the fluorine atoms of the two OC(CF<sub>3</sub>)<sub>3</sub> ligands. Reaction of <b>9</b> with Li(NIm<sup><i>t</i>Bu</sup>) resulted in partial cleavage of the Im<sup><i>t</i>Bu</sup>N ligand and ligand redistribution to afford the dinuclear tungsten alkylidyne complex <b>10</b>. The propylidyne complex [EtC≡W(NIm<sup><i>t</i>Bu</sup>){OCMe(CF<sub>3</sub>)<sub>2</sub>}<sub>2</sub>] (<b>12</b>) was obtained by treatment of <b>5a</b> with 3-hexyne, which proceeded via the metallacyclobutadiene complex <b>11</b>. Complex <b>5a</b> is able to rapidly catalyze alkyne cross-metathesis of 3-heptyne to give a statistical 1:2:1 mixture of 3-hexyne, 3-heptyne and 4-octyne. The catalytic homodimerization of 1-phenylpropyne under vacuum-driven conditions was studied for <b>5a</b>, <b>5b</b> and <b>6</b> at 30 and 80 °C. The molecular structures of complexes <b>2, 3</b>, <b>4a</b>, <b>4b</b>, <b>5b</b>, <b>8</b>, <b>9</b>, <b>10</b> and <b>12</b> were determined by single crystal X-ray diffraction. High-level DFT calculations employing the B3LYP functional have been carried out for a series of experimentally studied and other alkylidyne complexes by choosing alkyne metathesis of 2-butyne as the model reaction.