The isomeric C2NO+ ions NCCO+, CNCO+, CCNO+ and their neutral counterparts are stable species in the gas phase

The isomeric [C2NO] cations NCCO+, 1+, CNCO+, 2+ and CCNO+, 3+, were identified on the basis of their distinct collisional activation mass spectra. Reduction of these ions in a neutralization—reionization experiment produced intense survivor signals and characteristically different spectra which reveal the existence of NCCO, 1, CNCO, 2, and CCNO, 3., as stable radicals in the diluted gas phase.Ab initio (UMP3/6–31G*//6–31G* + ZPVE) MO calculations show that ions and neutrals 1 are more stable than their counterparts 2, by 7.4 and 15.8kcal mol−1 respectively. These calculations are not amenable to the determination of relative energies for ions and neutrals 3.