Conformational analysis and crystal structure of (<Emphasis Type="Italic">E</Emphasis>)-3-methyl-4-(<Emphasis Type="Italic">p</Emphasis>-tolyldiazenyl)phenol

The single crystal X-ray diffraction analysis of the title compound, C₁₄H₁₄N₂O, reveals that an interesting intermolecular or extended structure (hydrogen-bonded polymeric zigzag chains) is formed by linking its monomer units with O–H···N type intermolecular hydrogen bonds. The compound crystallizes in the monoclinic space group P2₁/n with a = 5.8151(5) Å, b = 18.106(1) Å, c = 11.515(1) Å  and β = 96.891(7)°. In order to understand better its structural aspects in solid state, quantum chemical (PM3) calculations were performed on a part of the extended structure of the title compound containing ten monomers. To determine in vacuo conformational flexibility of the compound, molecular energy profile of the title compound was obtained with respect to a selected torsional degree of freedom and the pedal angle varied from ?180° to +180° in every 10°. The results from the computational study suggest that hydrogen-bonding properties in the crystal lattice is fundamental in determining the crystallographically observed conformation of the title compound.