Synthesis, molecular and crystal structures of 4-amino-3,5-difluorobenzonitrile, ethyl 4-amino-3,5-difluorobenzoate, and diethyl 4,4'-(diazene-1,2-diyl)bis(3,5-difluorobenzoate).

The crystal structures of two inter­mediates, 4-amino-3,5-di­fluoro­benzo­nitrile, C₇H₄F₂N₂ (I), and ethyl 4-amino-3,5-difluorobenzoate, C₉H₉F₂NO₂ (II), along with a visible-light-responsive azo­benzene derivative, diethyl 4,4′-(diazene-1,2-di­yl)bis­(3,5-difluoro­benzoate), C₁₈H₁₄F₄N₂O₄ (III), obtained by four-step synthetic procedure, were studied using single-crystal X-ray diffraction. The mol­ecules of I and II demonstrate the quinoid character of phenyl rings accompanied by the distortion of bond angles related to the presence of fluorine substituents in the 3 and 5 (ortho) positions. In the crystals of I and II, the molecules are connected by N--H...N, N--H...F and N--H...O hydrogen bonds, C--H...F short contacts, and π-stacking inter­actions. In crystal of III, only stacking inter­actions between the molecules are found. [ABSTRACT FROM AUTHOR]