Direct C−H borylation of arenes catalyzed by saturated hydride‐boryl‐iridium‐POP complexes: Kinetic analysis of the elemental steps
The saturated trihydride IrH3{κ3‐P,O,P‐[xant(PiPr2)2]} (1; xant(PiPr2)2=9,9‐dimethyl‐4,5‐bis(diisopropylphosphino)xanthene) activates the B−H bond of two molecules of pinacolborane (HBpin) to give H2, the hydride‐boryl derivatives IrH2(Bpin){κ3‐P,O,P‐[xant(PiPr2)2]} (2) and IrH(Bpin)2{κ3‐P,O,P‐[xant...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2020 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/221711 |
| Acceso en línea: | http://hdl.handle.net/10261/221711 |
| Access Level: | acceso abierto |
| Palabra clave: | Arene borylation B-H activation C-H activation Iridium Pincer ligand |
| Sumario: | The saturated trihydride IrH3{κ3‐P,O,P‐[xant(PiPr2)2]} (1; xant(PiPr2)2=9,9‐dimethyl‐4,5‐bis(diisopropylphosphino)xanthene) activates the B−H bond of two molecules of pinacolborane (HBpin) to give H2, the hydride‐boryl derivatives IrH2(Bpin){κ3‐P,O,P‐[xant(PiPr2)2]} (2) and IrH(Bpin)2{κ3‐P,O,P‐[xant(PiPr2)2]} (3) in a sequential manner. Complex 3 activates a C−H bond of two molecules of benzene to form PhBpin and regenerates 2 and 1, also in a sequential manner. Thus, complexes 1, 2, and 3 define two cycles for the catalytic direct C−H borylation of arenes with HBpin, which have dihydride 2 as a common intermediate. C−H bond activation of the arenes is the rate‐determining step of both cycles, as the C−H oxidative addition to 3 is faster than to 2. The results from a kinetic study of the reactions of 1 and 2 with HBpin support a cooperative function of the hydride ligands in the B−H bond activation. The addition of the boron atom of the borane to a hydride facilitates the coordination of the B−H bond through the formation of κ1‐ and κ2‐dihydrideborate intermediates. |
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