Formation of O2CNO− in the reaction of with NO

Negatively-charged clusters of carbon dioxide, ( CO 2 ) n - , react with NO to form anions with [(CO2)m(NO)]− stoichiometry. The chemical identity of [(CO2)m(NO)]− is probed by photoelectron spectroscopy; the vertical detachment energy of the smallest product anion, [(CO2)(NO)]−, is determined to be 3.72 ± 0.04 eV. With the aid of ab initio calculations, [(CO2)(NO)]− is further identified as O2CNO−(1A′) having a covalent C–N linkage between the CO2 and NO units. These findings demonstrate that (1) ( CO 2 ) n - behaves as a CO 2 - radical anion in the gas-phase chemistry, and that (2) the relevant reaction proceeds as a radical addition process, CO 2 - + NO → O 2 CNO - ( 1 A ′ ) .