The two lowest electronic states of C5N: results of coupled cluster calculations

Using large-scale open-shell coupled cluster calculations the electronic ground state of C5N is predicted to have 2Σ symmetry, with the 2Π state lying ≈ 500 cm−1 higher in energy. The 2Σ state has a large equilibrium dipole moment of −3.385 D, with the negative end at the nitrogen site. The ground-state rotational constant is predicted to be 1397 ± 3 MHz. The adiabatic electron affinity of C5N is predicted to be 4.50 ± 0.05 eV and the CH equilibrium dissociation energy of HC5N is 588 kJ mol−1.