CCNN: the last kinetically stable isomer of cyanogen

The structure, vibrational frequencies, isomerization, and dissociation of CCNN were studied using the Hartree-Fock (HF), Moller-Plesset from second to fourth order (MP2, MP4SDQ, NP4SDTQ), configuration [CISD, QCSID, and QCISDT(T)] methods as well as the B3LYP and B3PW91 density functional theory methods. A schematic potential energy surface of the C₂N₂ was established at the QCISD(T)/6-311G(3df)//QCSIDT(T)/6-311G(d) single-point level. This enabled to compare the kinetic stability of CCNN with other C₂N₂ isomers. Finally, the possible formation of CCNN in laboratory and in interstellar space was confirmed.