Valence structures for N2O4. III

Further energies for types of N2O4 valence structures (or valence formulae) are reported. The results indicate that two sets of formulae might give satisfactory distributions of the mobile σ‐electrons. These are Resonance between covalent and ionic formulae ((B) and (D) of Part II[8]); A non‐paired spatial orbital formula ((F) of Part II [8]). One estimate of the σ‐bond order for the NN bond is 0.4–0.5. For this, (i) is to be preferred, because it involves a much lower energy than (ii). But should the order be about 0.7, the energies of (i) and (ii) are similar, and both descriptions are satisfactory. The ionic formula of (i) involves non‐localized bonding for the NO moiety. It may be replaced by a formula with localized bonds, and an almost identical energy.