Valence‐bond calculations on N 2 and isoelectronic species

Valence‐bond calculations are reported for the isoelectronic series of molecules and ions: N 2 , CO, BF, NO + and CN − . The most important structures are NN, CO, B π F, N + O and CN. Hybridization of the 2 s and 2 p orbitals is important. Only two or three structures are required to obtain an energy lower than that obtained with the molecular orbital approximation. Structures in which the electronegative element loses a σ‐orbital or gains a π‐orbital are favored. π‐bonds tend to be favored over σ‐bonds. The bond in NO + resembles that in CO, whereas that in CN − resembles the bonding in N 2 .