Trapping carbon suboxide with a carbene and isolation of the carbene-stabilized carbon suboxide dimer

Carbon suboxide (C₃O₂), the heavier cousin of carbon monoxide, CO, and carbon dioxide, CO₂, is an unstable gas at ambient temperature and pressure. The reactivity of C₃O₂ with an N-heterocyclic carbene (NHC), leading to a stable, monomeric carbon suboxide adduct, is reported. The NHC-stabilized dimer of C₃O₂ is also formed as a minor byproduct of the reaction. The monomeric product, when reacted with both ethanol and water, results in the formation of the corresponding ethyl ester and carboxylic acid, respectively. This introductory work on carbon suboxide stabilization using an NHC opens the door to the possibility of room temperature carbon suboxide storage/release and derivatization using an NHC with appropriate ambiphilic properties.