Stable and isolable carbanions: synthesis, chemical bonding, and unique applications

Carbanions were widely regarded as unstable and highly reactive species. However, in fact, the first example of stable and isolable carbanion-containing salts was reported more than 120 years ago. Recent research of stable carbanions endowed a renewed context such as carbanionic “substituents” for tuning the physicochemical properties of organic materials. In addition, unique electronic and geometric structures of the anionic carbon atom enable to be used as ionic liquids, polymer materials, and electrolytes. This review summarises notable recent advances in stable carbanions, covering their synthetic methodologies, chemical bonding behaviour, coordination chemistry, and emerging applications. In particular, carbanions stabilised by cyano, fluorinated sulfonyl, and phosphonio groups are discussed. • Synthetic methodologies of stable carbanion-containing salts. • Stabilising effects of anionic carbon atom by surrounding substituents. • Coordination chemistry of stable carbanions. • Several applications of stable carbanions.