Abstract One of the essential themes in modern catalysis is that of bridging the gap between its homogeneous and heterogeneous counterparts to combine their individual advantages and overcome shortcomings. One more incentive can now be added to the list, namely the ability of transition metal complexes to provide strong nuclear magnetic resonance (NMR) signal enhancement upon their use in homogeneous hydrogenations of unsaturated compounds with parahydrogen in solution. The addition of both H atoms of a parahydrogen molecule to the same substrate, a prerequisite for such effects, is implemented naturally with metal complexes that operate via the formation of a dihydride intermediate, but not with most heterogeneous catalysts. Despite that, it has been demonstrated in recent years that various types of heterogeneous catalysts are able to perform the required pairwise H2 addition at least to some extent. This has opened a major gateway for developing highly sensitive and informative tools for mechanistic studies of heterogeneous hydrogenations and other processes involving H2. Besides, production of catalyst-free fluids with NMR signals enhanced by 3-4 orders of magnitude is essential for modern applications of magnetic resonance imaging (MRI), including biomedical research and practice. The ongoing efforts to design heterogeneous catalysts which can implement the homogeneous (pairwise) hydrogenation mechanism are reported.

中文翻译：

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仲氢催化加氢：从均相催化到多相催化的桥梁

摘要 现代催化的基本主题之一是弥合同质和异质催化剂之间的差距，以结合各自的优势并克服缺点。现在可以向列表中添加另一个激励因素，即过渡金属配合物在使用溶液中的仲氢对不饱和化合物进行均相氢化时提供强核磁共振 (NMR) 信号增强的能力。将仲氢分子的两个 H 原子添加到同一底物上，这是这种效果的先决条件，通过金属配合物自然地实现，金属配合物通过形成二氢化物中间体而起作用，但不是大多数非均相催化剂。尽管那样，近年来已经证明，各种类型的非均相催化剂至少在一定程度上能够实现所需的成对 H2 添加。这为开发用于多相氢化和其他涉及 H2 过程的机械研究的高度敏感和信息丰富的工具打开了一个主要门户。此外，生产核磁共振信号增强 3-4 个数量级的无催化剂流体对于磁共振成像 (MRI) 的现代应用至关重要，包括生物医学研究和实践。据报道，目前正在努力设计可以实现均相（成对）氢化机制的多相催化剂。这为开发用于多相氢化和其他涉及 H2 过程的机械研究的高度敏感和信息丰富的工具打开了一个主要门户。此外，生产核磁共振信号增强 3-4 个数量级的无催化剂流体对于磁共振成像 (MRI) 的现代应用至关重要，包括生物医学研究和实践。据报道，目前正在努力设计可以实现均相（成对）氢化机制的多相催化剂。这为开发用于多相氢化和其他涉及 H2 过程的机械研究的高度敏感和信息丰富的工具打开了一个主要门户。此外，生产核磁共振信号增强 3-4 个数量级的无催化剂流体对于磁共振成像 (MRI) 的现代应用至关重要，包括生物医学研究和实践。据报道，目前正在努力设计可以实现均相（成对）氢化机制的多相催化剂。