N-Heterocyclic carbenes (NHCs) are an important class of reactive organic molecules used as ligands, organocatalysts, and σ-donors in a variety of electroneutral ylide or betaine adducts with main-group compounds. An emerging class of betaine adducts made from the reaction of NHCs with carbodiimides (CDIs) form zwitterionic amidinate-like structures with tunable properties based on the highly modular NHC and CDI scaffolds. The adduct stability is controlled by the substituents on the CDI nitrogens, while the NHC substituents greatly affect the configuration of the adduct in the solid state. This Perspective is intended as a primer to these adducts, touching on their history, synthesis, characterization, and general properties. Despite the infancy of the field, NHC–CDI adducts have been applied as amidinate-type ligands for transition metals and nanoparticles, as junctions in zwitterionic polymers, and to stabilize distonic radical cations. These applications and potential future directions are discussed.

中文翻译：

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N-杂环卡宾-碳二亚胺（NHC-CDI）甜菜碱加合物：合成，表征，性质和应用

N-杂环卡宾（NHC）是一类重要的反应性有机分子，在各种电中性叶立德或甜菜碱与主族化合物的加合物中用作配体，有机催化剂和σ供体。由NHC与碳二亚胺（CDI）反应制得的一类新兴的甜菜碱加合物基于高度模块化的NHC和CDI支架形成具有可调性质的两性离子a酰胺样结构。加合物的稳定性受CDI氮上的取代基控制，而NHC取代基极大地影响了固态下加合物的构型。这个观点旨在作为这些加合物的入门，涉及它们的历史，合成，表征和一般性质。尽管该领域还处于起步阶段，但NHC-CDI加合物已被用作过渡金属和纳米粒子的a酸盐型配体，用作两性离子聚合物中的结，并能稳定二甲苯基阳离子。讨论了这些应用和潜在的未来方向。