The molecular structures and energetics of diazirine molecule (H2CN2 ), diazirinyl (HCN2), diazomethyl (HCNN) and cyanomidyl (HNCN) radicals and their related cations (H2CN+ , HCN+ , HCNN+ , HNCN+ ) and anions (HCNN&#8722, , HNCN&#8722, ) have been investigated at a high level of accuracy. The coupled-cluster method with systematic sequences of correlation consistent basis set has been employed. Extrapolation to the complete basis set limit has been used with accurate treatments of core-valence correlation effects. For all the species studied, harmonic vibrational frequencies have also been evaluated in order to obtain zero-point corrections to ionization potentials, electron affinities, and C&#8211,H and N&#8211,H bond dissociation energies.
