Stoichiometric and Catalytic H/D Incorporation by Cationic Iridium Complexes: A Common Monohydrido-Iridium Intermediate
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- 作者：Cathleen M. Yung ; Marc B. Skaddan ; and Robert G. Bergman
- 刊名：Journal of the American Chemical Society
- 出版年：2004
- 出版时间：October 13, 2004
- 年：2004
- 卷：126
- 期：40
- 页码：13033 - 13043
- 全文大小：211K
- 年卷期：v.126,no.40(October 13, 2004)
- ISSN：1520-5126
文摘
A mechanistic study of the stoichiometric and catalytic H/D exchange reactions involving cationiciridium complexes is presented. Strong evidence suggests that both stoichiometric and catalytic reactionsproceed via a monohydrido-iridium species. Stoichiometric deuterium incorporation reactions introducemultiple deuterium atoms into the organic products when aryliridium compounds Cp*PMe3Ir(C6H4X)(OTf)(X = H, o-CH3, m-CH3, p-CH3) react with D2. Multiple deuteration occurs at the unhindered positions (paraand meta) of toluene, when X = CH3. The multiple-deuteration pathway is suppressed in the presence ofan excess of the coordinating ligand, CH3CN. The compound Cp*PMe3IrH(OTf) (1-OTf) is observed inlow-temperature, stoichiometric experiments to support a monohydrido-iridium intermediate that isresponsible for catalyzing multiple deuteration in the stoichiometric system. When paired with acetone-d6,[Cp*PMe3IrH3][OTf] (4) catalytically deuterates a wide range of substrates with a variety of functional groups.Catalyst 4 decomposes to [Cp*PMe3Ir(
3-CH2C(OH)CH2)][OTf] (19) in acetone and to [Cp*PMe3IrH(CO)][OTf] (1-CO) in CH3OH. The catalytic H/D exchange reaction is not catalyzed by simple H+ transfer, butinstead proceeds by a reversible C-H bond activation mechanism.
3-CH2C(OH)CH2)][OTf] (19) in acetone and to [Cp*PMe3IrH(CO)][OTf] (1-CO) in CH3OH. The catalytic H/D exchange reaction is not catalyzed by simple H+ transfer, butinstead proceeds by a reversible C-H bond activation mechanism.