Transition metal catalysis is of utmost importance for the development of sustainable processes in academia and industry. The activity and selectivity of metal complexes are typically the result of the interplay between ligand and metal properties. As the ligand can be chemically altered, a large research focus has been on ligand development. More recently, it has been recognized that further control over activity and selectivity can be achieved by using the “second coordination sphere”, which can be seen as the region beyond the direct coordination sphere of the metal center. Hydrogen bonds appear to be very useful interactions in this context as they typically have sufficient strength and directionality to exert control of the second coordination sphere, yet hydrogen bonds are typically very dynamic, allowing fast turnover. In this review we have highlighted several key features of hydrogen bonding interactions and have summarized the use of hydrogen bonding to program the second coordination sphere. Such control can be achieved by bridging two ligands that are coordinated to a metal center to effectively lead to supramolecular bidentate ligands. In addition, hydrogen bonding can be used to preorganize a substrate that is coordinated to the metal center. Both strategies lead to catalysts with superior properties in a variety of metal catalyzed transformations, including (asymmetric) hydrogenation, hydroformylation, C–H activation, oxidation, radical-type transformations, and photochemical reactions.

中文翻译：

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第二配位球中氢键控制的过渡金属催化

过渡金属催化对于学术界和工业界可持续工艺的发展至关重要。金属配合物的活性和选择性通常是配体和金属性质相互作用的结果。由于配体可以被化学改变，一个大的研究重点一直放在配体的开发上。最近，人们认识到可以通过使用“第二配位范围”来进一步控制活性和选择性，这可以看作是金属中心直接配位范围之外的区域。在这种情况下，氢键似乎是非常有用的相互作用，因为它们通常具有足够的强度和方向性来控制第二个配位球，但氢键通常是非常动态的，允许快速周转。在这篇综述中，我们强调了氢键相互作用的几个关键特征，并总结了使用氢键对第二配位球进行编程。这种控制可以通过桥接与金属中心配位的两个配体来实现，从而有效地产生超分子双齿配体。此外，氢键可用于预组织与金属中心配位的底物。这两种策略都导致催化剂在各种金属催化转化中具有优异的性能，包括（不对称）氢化、加氢甲酰化、C-H 活化、氧化、自由基型转化和光化学反应。这种控制可以通过桥接与金属中心配位的两个配体来实现，从而有效地产生超分子双齿配体。此外，氢键可用于预组织与金属中心配位的底物。这两种策略都导致催化剂在各种金属催化转化中具有优异的性能，包括（不对称）氢化、加氢甲酰化、C-H 活化、氧化、自由基型转化和光化学反应。这种控制可以通过桥接与金属中心配位的两个配体来实现，从而有效地产生超分子双齿配体。此外，氢键可用于预组织与金属中心配位的底物。这两种策略都导致催化剂在各种金属催化转化中具有优异的性能，包括（不对称）氢化、加氢甲酰化、C-H 活化、氧化、自由基型转化和光化学反应。