Interaction of the early 3d transition metals Sc, Ti, V, and Cr with N2: an ab initio study

The interaction of the early 3d transition elements M=Sc, Ti, V, and Cr with N2(X 1Sigmag+) has been studied by coupled-cluster and multiconfigurational techniques in conjunction with quantitative basis sets. We investigated both triatomic (MN2) and tetratomic (M2N2) species but focused mainly on high-spin linear and T-shaped triatomics. The lowest bound states of ScN2(4B1),TiN2(5Delta), and VN2(6Sigma+) correlate to the first excited state of the M atom, with M-N2 binding energies (De) of 24, 14, and 8 kcal/mol, respectively. In CrN2, the first bound state (7) product operator correlates to the sixth excited state of the Cr atom (7P) with De = 27 kcal/mol. The M-N2-M bond strength of high-spin linear tetratomics is twice as large the binding energy of the corresponding M-N2 linear triatomics, M = Sc, Ti, V, and Cr.