Collect. Czech. Chem. Commun. 1990, 55, 165-179

Crystal and molecular structure of potassium p-nitrophenolate monohydrate: Substituent effect on geometry of the ring in p-substituted nitrobenzene derivatives

T. M. Krygowski and I. Turowska-Tyrk

Department of Chemistry, University of Warsaw, 02 093 Warsaw, Poland


The crystal and molecular structure of potassium p-nitrophenolate monohydrate has been determined by X-ray diffraction methods giving R = 0.050. The through resonance effect between -O- and -NO2 groups resulted in a significant deformation of the ring geometry. Application of the HOSE model yielded in determination of the resonance structure contributions and offered an argument against the classical view of the through resonance effect: percentage contribution of quinoid form with full charge transfer from -O- to -NO2 was found to be the least significant of all four possible quinoid structures. Contributions of quinoid and benzenoid structures plotted against σ+ or σp constants for 14 p-systems give a reasonable linear dependence. Application of the additive scheme of substituent effect to the same series of compounds proved a strong reasonance effect from electron donating substituents and a much weaker one (and constant in the whole series) from the nitro group.