Determination of the CC bond dissociation energy in cyanogen

The CC bond dissociation energy (Do) in cyanogen is predicted using many-body perturba- tion (MP) and quadratic configuration interaction theory [QCISD(T)]. The dissociation limit is poorly predicted with many-body perturbation theory. At the QCISD(T)/6-311G(3df)//QCISD(T)/ 6-311G(2d) level of theory, the bond dissociation energy is predicted to be 132.8±2 kcal mol−1, which is in excellent agreement with experiment.