UCR-CNRS Joint Research Chemistry Laboratory (UMI 2957), Departement of Chemistry, University of California, Riverside, CA 92521-0403, USA.
Angew Chem Int Ed Engl. 2010 Nov 15;49(47):8810-49. doi: 10.1002/anie.201000165.
The success of homogeneous catalysis can be attributed largely to the development of a diverse range of ligand frameworks that have been used to tune the behavior of various systems. Spectacular results in this area have been achieved using cyclic diaminocarbenes (NHCs) as a result of their strong σ-donor properties. Although it is possible to cursorily tune the structure of NHCs, any diversity is still far from matching their phosphorus-based counterparts, which is one of the great strengths of the latter. A variety of stable acyclic carbenes are known, but they are either reluctant to bind metals or they give rise to fragile metal complexes. During the last five years, new types of stable cyclic carbenes, as well as related carbon-based ligands (which are not NHCs), and which feature even stronger σ-donor properties have been developed. Their synthesis and characterization as well as the stability, electronic properties, coordination behavior, and catalytic activity of the ensuing complexes are discussed, and comparisons with their NHC cousins are made.
均相催化的成功在很大程度上可以归因于各种配体框架的发展，这些配体框架被用于调节各种体系的行为。使用环状二氨基卡宾（NHCs）作为强σ-给体性质的结果，在该领域取得了惊人的成果。尽管可以粗略地调整 NHC 的结构，但任何多样性仍然远远不及它们的磷基对应物，这是后者的一大优势。已知有多种稳定的非环状卡宾，但它们要么不愿意与金属结合，要么会导致脆弱的金属配合物。在过去的五年中，已经开发出新型稳定的环状卡宾以及相关的基于碳的配体（不是 NHC），这些配体具有更强的σ-给体性质。讨论了它们的合成和表征以及随之而来的配合物的稳定性、电子性质、配位行为和催化活性，并与它们的 NHC 同类物进行了比较。
