Crystallographic and conformational analysis of (E)-2-isopropyl-4-(p-tolyldiazenyl)phenol

The molecular and crystal structures of the title compound, C 16 H 18 N 2 O, were characterized and determined by single crystal X-ray diffraction method in addition to spectroscopic means such as IR, UV–VIS and 1 H NMR. The compound crystallizes in orthorhombic space group P bca , with a = 9.3350(5) Å, b = 23.4878(13) Å, c = 26.5871(12) Å, Z = 16, D calc. = 1.1591(1) g/cm 3 , μ (MoK α ) = 0.073 mm −1 . Monomers of the compound in the crystal structure are linked into C(7) and C(8) chains generated by translation along the [1 0 0] direction with the aid of O–H···N type H-bonds which serve to the stabilization of periodic organization of the molecules beside major and minor component in the disordered azo fragment. In order to describe conformational flexibility and the crystal packing effects on the molecular conformation, potential barriers regarding the rotation along both Ar–N bonds were calculated by varying the related torsional degrees of freedom in every 10° ranging from −180° to +180° via quantum chemical calculations at DFT/B3LYP level.