Structure and Decomposition Barrier of the Ethyldiazenyl Radical

[[abstract]]The structure and dissociation of ground-state (2A′) C2H5N2, the ethyldiazenyl radical, were studied using ab initio quantum mechanical techniques, including the self-consistent-field (SCF), single and double excitation configuration interaction (CISD), single and double excitation coupled cluster (CCSD) and single, double and perturbative triple excitation coupled cluster (CCSD(T)). The activation barrier for the decomposition of the ethyldiazenyl radical to form N2 plus C2H5 was predicted to be smaller than that of CH3N2. The tunneling frequency of C2H5N2 estimated within the Wentzel-Kramers-Brillouin approximation gave a tunneling rate corresponding to a lifetime of 0.3 ps for the ground vibrational state. The energetics and rate of C2H5N2 decomposition are similar to those of the methyldiazenyl radical CH3N2, and are very different from those of HN2, the lifetime of which is in the nanosecond range