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首页> 外文期刊>RSC Advances >Ruthenium hydroxycyclopentadienyl N-heterocyclic carbene complexes as transfer hydrogenation catalysts
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Ruthenium hydroxycyclopentadienyl N-heterocyclic carbene complexes as transfer hydrogenation catalysts

机译：钌羟基环戊二烯基N-杂环卡宾配合物作为转移氢化催化剂

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摘要

A series of novel cationic hydroxycyclopentadienyl and methoxycyclopentadienyl N-heterocyclic carbene ruthenium(II) complexes have been synthesized from the corresponding neutral ruthenium(0) complexes containing both the non-innocent cyclopentadienone ligand and variously functionalized N-heterocyclic carbenes (NHCs). In particular an NHC derivative containing a pyridine group in the side chain has been designed and developed in order to evaluate the influence of a basic, potentially cooperative substituent in the catalytic activity of these complexes. All the prepared complexes were employed as selective catalysts for transfer hydrogenation reactions employing refluxing (PrOH)-Pr-i as a hydrogen source and several ketones and aldehydes as substrates. We found that while the presence of oxidizing additives such as CAN and benzoquinone is mandatory to activate the neutral ruthenium(0) complexes, no activation is needed for the cationic Ru(II) catalysts. The catalytic activity of the latter is also influenced by the coordinating ability of the counterion, and indeed the cationic complexes having a pyridine-functionalized NHC ligand and CF3SO3- as counterion, present the best conversion (>99%) thus demonstrating the fundamental role played by the basic pyridine in the catalytic activity. With regard to the hydrogenation reaction mechanism, the release of the CO ligand was demonstrated to be the key step and the presence of hydride species has been detected at the end of the reaction.
机译：一系列新型阳离子羟基环戊二烯基和甲氧基环戊二烯基N-杂环丁烯钌（II）配合物已从含有非无辜环戊二烯酮配体和各种官能化的N-杂环碳酸（NHC）的相应中性钌（0）络合物中合成。特别是设计和开发含有侧链中吡啶基团的NHC衍生物，以评估基本，可能的合作取代基在这些配合物的催化活性的影响。所有制备的配合物都是用作转移氢化反应的选择性催化剂，用于使用回流（PROH）-PR-1作为氢气源和几种酮和醛作为底物。我们发现，虽然氧化添加剂如罐和苯醌的存在是强制性的，但是激活中性钌（0）络合物，则阳离子Ru（II）催化剂不需要活化。后者的催化活性也受到抗衡离子的配位能力的影响，并且实际上具有吡啶官能化的NHC配体和CF3SO3-作为抗衡离子的阳离子复合物，并呈现最佳转化（> 99％），从而展示了所扮演的基本作用通过催化活性的碱性吡啶。关于氢化反应机理，CO配体的释放被证明是关键步骤，并在反应结束时检测到氢化物物质的存在。

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  • 来源
    《RSC Advances》 |2015年第115期|共12页
  • 作者

    Cesari Cristiana; Cingolani Andrea; Parise Chiara; Zacchini Stefano; Zanotti Valerio; Cassani Maria Cristina; Mazzoni Rita;

  • 作者单位

    Dipartimento Chim Ind Toso Montanari I-40136 Bologna Italy;

    Dipartimento Chim Ind Toso Montanari I-40136 Bologna Italy;

    Dipartimento Chim Ind Toso Montanari I-40136 Bologna Italy;

    Dipartimento Chim Ind Toso Montanari I-40136 Bologna Italy;

    Dipartimento Chim Ind Toso Montanari I-40136 Bologna Italy;

    Dipartimento Chim Ind Toso Montanari I-40136 Bologna Italy;

    Dipartimento Chim Ind Toso Montanari I-40136 Bologna Italy;

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  • 正文语种 eng
  • 中图分类 化学;
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