期刊
CHEMISTRY-A EUROPEAN JOURNAL
卷 21, 期 46, 页码 16564-16577出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/chem.201501074
关键词
density functional calculations; homogeneous catalysis; imines; iridium; transfer hydrogenation
资金
- University College, London
- Pfizer
- University of Liverpool
- EPSRC [EP/K039687/1] Funding Source: UKRI
- Engineering and Physical Sciences Research Council [EP/K039687/1] Funding Source: researchfish
The mechanism of imine reduction by formic acid with a single-site iridicycle catalyst has been investigated by density functional theory (DFT), NMR spectroscopy, and kinetic measurements. The NMR and kinetic studies suggest that the transfer hydrogenation is turnover-limited by the hydride formation step. The calculations reveal that, amongst a number of possibilities, hydride formation from the iridicycle and formate probably proceeds by an ion-pair mechanism, whereas the hydride transfer to the imino bond occurs in an outer-sphere manner. In the gas phase, in the most favourable pathway, the activation energies in the hydride formation and transfer steps are 26-28 and 7-8kcalmol(-1), respectively. Introducing one explicit methanol molecule into the modelling alters the energy barrier significantly, reducing the energies to around 18 and 2kcalmol(-1) for the two steps, respectively. The DFT investigation further shows that methanol participates in the transition state of the turnover-limiting hydride formation step by hydrogen-bonding to the formate anion and thereby stabilising the ion pair.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据