The N4O62+group: X-ray crystal structure of Fe(NO3)3,1·5N2O4

The crystal structure of the adduct Fe(NO3)3,–1·5N2O4 indicates that it should be represented as 3NO+,NO3–,2[Fe(NO3)4–]; vibrational spectroscopy provides evidence for interaction between the NO3– and 3NO+ ions, and the properties are correlated in terms of a weakly bonded N4O62+ group which may also be present in solutions of N2O4, or the adduct, in pure nitric acid.