Ammonia-Borane dehydrogenation promoted by an osmium dihydride complex: Kinetics and mechanism
Complex OsH2(CO)(PiPr3)2, generated from OsH2(CO)(η2-CH2═CHEt)(PiPr3)2 by dissociation of the olefin, promotes the release of 1 equiv of H2 from ammonia-borane and the formation of polyaminoborane. The dehydrogenation rate law is of the form d[H2]/dt = k[Os] with activation parameters of ΔH‡ = 19.6...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2015 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/118271 |
| Acceso en línea: | http://hdl.handle.net/10261/118271 |
| Access Level: | acceso abierto |
| Sumario: | Complex OsH2(CO)(PiPr3)2, generated from OsH2(CO)(η2-CH2═CHEt)(PiPr3)2 by dissociation of the olefin, promotes the release of 1 equiv of H2 from ammonia-borane and the formation of polyaminoborane. The dehydrogenation rate law is of the form d[H2]/dt = k[Os] with activation parameters of ΔH‡ = 19.6 ± 2.5 kcal·mol–1 and ΔS‡ = 6 ± 9 cal·mol–1·K–1. On the basis of kinetic results, spectroscopic NMR observations, and DFT calculations, the dihydride-dihydrogen derivative OsH2(η2-H2)(CO)(PiPr3)2 is proposed as a key intermediate for the dehydrogenation. Its formation involves the concerted BH- and NH-hydrogen transfers from the amine-borane to the metal center and to a hydride ligand, respectively. |
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