Pendant amines play an invaluable role in chemical reactivity, especially for molecular catalysts based on earth-abundant metals. As inspired by [FeFe]-hydrogenases, which contain a pendant amine positioned for cooperative bifunctionality, synthetic catalysts have been developed to emulate this multifunctionality through incorporation of a pendant amine in the second coordination sphere. Cyclic diphosphine ligands containing two amines serve as the basis for a class of catalysts that have been extensively studied and used to demonstrate the impact of a pendant base. These 1,5-diaza-3,7-diphosphacyclooctanes, now often referred to as “P₂N₂” ligands, have profound effects on the reactivity of many catalysts. The resulting [Ni(P^R₂N^R′₂)₂]²⁺ complexes are electrocatalysts for both the oxidation and production of H₂. Achieving the optimal benefit of the pendant amine requires that it has suitable basicity and is properly positioned relative to the metal center. In addition to the catalytic efficacy demonstrated with [Ni(P^R₂N^R′₂)₂]²⁺ complexes for the oxidation and production of H₂, catalysts with diphosphine ligands containing pendant amines have also been demonstrated for several metals for many different reactions, both in solution and immobilized on surfaces. The impact of pendant amines in catalyst design continues to expand.

中文翻译：

---

含有侧胺的二膦配体的分子催化剂

侧胺在化学反应中发挥着不可估量的作用，特别是对于基于地球丰富金属的分子催化剂。受 [FeFe]-氢化酶的启发，其中含有一个用于协同双功能的侧胺，已开发出合成催化剂以通过在第二个配位域中掺入一个侧胺来模拟这种多功能性。含有两种胺的环状二膦配体作为一类催化剂的基础，该类催化剂已被广泛研究并用于证明侧基的影响。这些 1,5-diaza-3,7-diphosphacyclooctanes，现在通常称为“P ₂ N ₂ ”配体，对许多催化剂的反应性具有深远的影响。所得[Ni(P ^R ₂ N ^R'₂ ) ₂ ] ²⁺配合物是氧化和生产H ₂的电催化剂。实现侧胺的最佳效益要求它具有合适的碱度并相对于金属中心适当定位。除了用[Ni(P ^R ₂ N ^R' ₂ ) ₂ ] ²⁺配合物证明的用于氧化和生产H _{2的催化功效外}，具有含侧胺的二膦配体的催化剂也已被证明可用于多种金属，用于许多不同的反应，无论是在溶液中还是固定在表面上。侧胺对催化剂设计的影响继续扩大。