Lithium Di-‐ and Trimethyl Dimolybdenum(II) Complexes with Mo-‐Mo Quadruple Bonds and Bridging Methyl Groups
New dimolybdenum complexes of composition [Mo2{μ-Me}2Li(S)}(μ- X)(μ-N^N)2] (3a−3c), where S = THF or Et2O and N^N represents a bidentate aminopyridinate or amidinate ligand that bridges the quadruply bonded molybdenum atoms, were prepared from the reaction of the appropriate [Mo2{μ-O2CMe}2(μ-N^N)2]...
| Autores: | , , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2015 |
| País: | España |
| Institución: | Universidad de Sevilla (US) |
| Repositorio: | idUS. Depósito de Investigación de la Universidad de Sevilla |
| OAI Identifier: | oai:idus.us.es:11441/66266 |
| Acceso en línea: | http://hdl.handle.net/11441/66266 https://doi.org/10.1021/jacs.5b07899 |
| Access Level: | acceso abierto |
| Palabra clave: | Bridging methyl groups Multiple bonds Molybdenum NMR spectroscopy Competitional studies |
| Sumario: | New dimolybdenum complexes of composition [Mo2{μ-Me}2Li(S)}(μ- X)(μ-N^N)2] (3a−3c), where S = THF or Et2O and N^N represents a bidentate aminopyridinate or amidinate ligand that bridges the quadruply bonded molybdenum atoms, were prepared from the reaction of the appropriate [Mo2{μ-O2CMe}2(μ-N^N)2] precursors and LiMe. For complex 3a, X = MeCO2, while in 3b and 3c, X = Me. Solution NMR studies in C6D6 solvent support formulation of the complexes as contact ion pairs with weak agostic Mo−CH3···Li interactions, which were also evidenced by X-ray crystallography in the solid-state structures of the molecules of 3a and 3b. Samples of 3c enriched in 13C (99%) at the metal-bonded methyl sites were also prepared and investigated by NMR spectroscopy employing C6D6 and THF-d8 solvents. Crystallization of 3c from toluene:tetrahydrofuran mixtures provided single crystals of the solvent separated ion pair complex [Li(THF)4] [Mo2(Me)2(μ-Me){μ-HC(NDipp)2}2] (4c), where Dipp stands for 2,6-iPr2C6H3. A computational analysis of the Mo2(μ-Me)2Li core of complexes 3a and 3b has been developed, which is consistent with a small but non-negligible electron-density sharing between the C and Li atoms of the mainly ionic CH3···Li interactions. |
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