The covalently bound HNC dimer ion HNCCNH+ has a kinetically stable neutral counterpart

Neutralization-reionization mass spectrometry (NRMS) and computational chemistry (CBS-QB3/APNO methods) have been used to show that HNCCNH (ethenediimine) and its isomer H2N–C–CN (aminocyanocarbene) are generated as kinetically stable molecules in the rarefied gas-phase by one electron reduction of their ionic precursors. ute to the very stable ion HNCC NH + involves loss of HCN from the hydrogen-bridged radical cation [ HNC ⋯ H 2 N – C – CN ] + via a remarkable quid-pro-quo catalysis in which both the ion and the neutral undergo isomerization.