International Union of Crystallography, Acta Crystallographica Section C: Structural Chemistry, 9(70), p. 837-842, 2014
DOI: 10.1107/s2053229614017173
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The title substituted pyrazole derivatives, C17H15N5O3and C18H15F3N4O, share most of their molecular features, in particular the hydrazinylidene (–HN—N=) rather than the diazene (–N=N–) tautomeric form, and differ only in the substituents (NO2and CF3) on one of the outer phenyl rings. The molecular units are basically planar, with the rotation of the phenyl rings being hindered by the presence of two intramolecular hydrogen bonds having the keto O atom as acceptor. In both structures, the packing is governed by weak C—H...O, C—H...π and π–π interactions. The subtle way in which minor structural differences lead to rather different supramolecular structures is analysed.