title: Rhodium-Catalyzed Dehydrogenative Silylation of Acetophenone Derivatives: Formation of Silyl Enol Ethers versus Silyl Ethers.
abstract: A series of rhodium-NSiN complexes (NSiN=bis (pyridine-2-yloxy)methylsilyl fac-coordinated) is reported, including the solid-state structures of [Rh(H)(Cl)(NSiN)(PCy3 )] (Cy=cyclohexane) and [Rh(H)(CF3 SO3 )(NSiN)(coe)] (coe=cis-cyclooctene). The [Rh(H)(CF3 SO3 )(NSiN)(coe)]-catalyzed reaction of acetophenone with silanes performed in an open system was studied. Interestingly, in most of the cases the formation of the corresponding silyl enol ether as major reaction product was observed. However, when the catalytic reactions were performed in closed systems, formation of the corresponding silyl ether was favored. Moreover, theoretical calculations on the reaction of [Rh(H)(CF3 SO3 )(NSiN)(coe)] with HSiMe3 and acetophenone showed that formation of the silyl enol ether is kinetically favored, while the silyl ether is the thermodynamic product. The dehydrogenative silylation entails heterolytic cleavage of the Si-H bond by a metal-ligand cooperative mechanism as the rate-determining step. Silyl transfer from a coordinated trimethylsilyltriflate molecule to the acetophenone followed by proton transfer from the activated acetophenone to the hydride ligand results in the formation of H2 and the corresponding silyl enol ether.
authors.affiliation: Universidad de Zaragoza, CSIC, Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea, ISQCH), Facultad de Ciencias, 50009, Zaragoza, Spain.
authors.forename: Karin
authors.initials: K
authors.lastname: Garcés
authors.affiliation: Universidad de Zaragoza, CSIC, Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea, ISQCH), Facultad de Ciencias, 50009, Zaragoza, Spain.
authors.forename: Ralte
authors.initials: R
authors.lastname: Lalrempuia
authors.affiliation: Departamento de Química Física, Instituto de Biocomputación y Física de Sistemas complejos, BIFI), Universidad de Zaragoza, Facultad de Ciencias, 50009, Zaragoza, Spain.
authors.forename: Víctor
authors.initials: V
authors.lastname: Polo
authors.affiliation: Universidad de Zaragoza, CSIC, Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea, ISQCH), Facultad de Ciencias, 50009, Zaragoza, Spain. paco@unizar.es.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Fernández-Alvarez
authors.affiliation: Universidad de Zaragoza, CSIC, Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea, ISQCH), Facultad de Ciencias, 50009, Zaragoza, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: García-Orduña
authors.affiliation: Universidad de Zaragoza, CSIC, Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea, ISQCH), Facultad de Ciencias, 50009, Zaragoza, Spain.
authors.forename: Fernando J
authors.initials: FJ
authors.lastname: Lahoz
authors.affiliation: Universidad de Zaragoza, CSIC, Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea, ISQCH), Facultad de Ciencias, 50009, Zaragoza, Spain.
authors.forename: Jesús J
authors.initials: JJ
authors.lastname: Pérez-Torrente
authors.affiliation: Universidad de Zaragoza, CSIC, Departamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea, ISQCH), Facultad de Ciencias, 50009, Zaragoza, Spain. oro@unizar.es.|Center of Research Excellence in Petroleum Refining and Petrochemicals, King Fahd University of Petroleum and Minerals, 31261, Dhahran, Saudi Arabia. oro@unizar.es.
authors.forename: Luis A
authors.initials: LA
authors.lastname: Oro
keywords: NSiN ligands; dehydrogenative silylation; hydrogenation; hydrosilylation; rhodium; silyl enol ethers