Discovered more than two decades ago, stable carbenes (R 2 C) now have a broad range of applications ranging from synthetic chemistry to material and biological sciences. Bertrand and colleagues show that with the right substituents, the phosphorus analogs, namely phosphinidenes (RP), can be isolated at room temperature.

An acidic hydride! Thanks to the presence of a π-acceptor cyclic (alkyl)(amino)carbene (CAAC) and of two electron-withdrawing nitrile groups, a borohydride reacts with a base to give a carbenestabilized boryl anion, which reacts with carbon and metal electrophiles at the boron center.

A cyclic alkyl(amino)carbene readily reacts with SbCl3 to form the corresponding Sb(III) adduct. One-electron reduction gives rise to the first example of a neutral antimony-centered radical characterized in solution. Two-electron reduction affords a Lewis base stabilized chloro-stibinidene, whereas three-electron reduction gives an antimony diatomic species capped by two carbenes. The radical has been characterized by EPR spectroscopy, while the structure of the other three species has been ascertained by single-crystal X-ray diffraction. In these four species, the formal oxidation state of the metalloid diminishes from III, to II, to I, and finally 0.

Sodium phosphaethynolate reacts with [MCl(PDI)] (M = Co, Ir; PDI = pyridinediimine) to give metallaphosphaketenes, which in the case of iridium rearranges into a dimetalladiphosphene.