Fixation of nitrous oxide by mesoionic and carbanionic N-heterocyclic carbenes

A ditopic carbanionic N-heterocyclic carbene was found to react with the inert gas nitrous oxide, resulting in a stable covalent adduct with two intact N2O groups attached to the heterocycle. Mesoionic N-heterocyclic carbenes derived from C2-arylated 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene are also able to form adducts with one or two N2O groups. Crystallographic analyses of all adducts reveal bent N2O groups, which can adopt a cis or trans configuration.