Reinvestigation of the Structure of Dinitrogen Tetroxide, N2O4, by Gaseous Electron Diffraction

• Published in: The Journal of chemical physics 1972-05, Vol.56 (9), p.4541-4545
• Main Authors: McClelland, Bruce W., Gundersen, Grete, Hedberg, Kenneth
• Format: Article
• Language: English
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.1677901

A reinvestigation of the structure of N2O4 in the gas phase at −21oC has given results in good agreement with an earlier study so far as the molecular shape is concerned, but the size of the molecule appears to be about 0.9% larger than originally thought. The results for the coplanar (D2h symmetry) model are: rNN = 1.782 Å (0.0083), rNO = 1.190 Å (0.0018), ∠ ONO = 135.4o (0.58),  lNN = 0.0816  Å  (0.0178), lNO = 0.0381 Å (0.0019), lo1o2 = 0.0493 Å (0.0040), lN···O = 0.0729 Å (0.0061), lo1o1′ = 0.0970 Å (0.0167), and lo1o2′ = 0.0730 Å (0.0114). These distances and root-mean-square amplitudes are ra and la values; the parenthesized values are 2σ and include estimates of systematic error. The −NO2 groups have a structure very similar to that of NO2 itself. The very long N–N bond and its large amplitude of vibration imply a weak link and are in accord with the low dissociation energy.