Theoretical prediction of ionization potential, electron affinity, and electronic spectrum of the S 2 N radical

Ab initio MRD – CI calculations using a basis set of near Hartree–Fock quality have been carried out to calculate the ground‐state electronic structure of S 2 N + , S 2 N, and S 2 N − and the ionization potential, electron affinity, and vertical electronic spectrum of S 2 N. At the highest level of theory (estimated full CI or FCI ), S 2 N + is predicted to have a linear structure with r ( N S ) = 1.51 Å. For S 2 N and S 2 N − , the minimum in energy at the FCI level corresponds to a quasi‐linear [with a barrier height to linearity of about 2.0 kcal mol −1 , ] and a bent structure , respectively. The adiabatic/vertical ionization potential and electron affinity of S 2 N are predicted to be 7.26/7.82 and 1.60/0.79 eV, respectively. Of the several electronic transitions in S 2 N considered, the ones with the excitation energy of 1.87 eV ( X 2 A 1 → 2 B 2 ) and 2.87 eV ( X 2 A 1 → 2 B 2 ) are somewhat intense (ƒ = 0.005 and 0.002) and likely to be observed.