The isomeric ions produced by the gas phase protonation of HNCO and HCNO

Ab initio molecular orbital theory calculations combined with mass spectrometric experiments show that the gas phase protonation of HNCO yields [H2NCO]+ (ΔHf0=672 kJ mol−1), whereas HCNO produces [HCNOH]+ (ΔHf0=990 kJ mol −1). The proton affinity of fulminic acid, HCNO, is estimated to be 758 kJ mol−1.