The isolation of a rare example of a highly reactive low-valent carbon compound-a carbyne anion complex-enables the discovery of low-valent carbon transfer reactions. Carbon reactive species are key intermediates in several CC and C-X bond forming reactions-the basic transformations chemists use to build complex molecules with control of structure and functionality. Over the years, a variety of highly reactive carbon species have been isolated, or at least characterized, enabling progress in synthesis. While trivalent and divalent compounds are now well-known and quite common (Fig. 1a), related monovalent species remain extremely scant. The high degree of unsaturation further enhances the reactivity of anionic, cationic and radical centres, making them attractive species but also challenging compounds to synthesize and stabilize. In 2018, carbyne equivalents 1 (monovalent carbon species with three non-bonded electrons) were generated and their dual radical-carbene reactivity exploited to forge three covalent bonds.