Computational and experimental studies of 2-[(E)-hydrazinylidenemethyl]-6-methoxy-4-[(E)-phenyldiazenyl]phenol and its tautomers

• A new azo-Schiff base was synthesized.
• The structure of the compound was determined by X-ray diffraction.
• Computational calculations have been performed using DFT methods.
• Thermodynamic parameters were used to determine the most stable tautomer.
• Chemical reactivity of the compound were investigated using some quantum chemical parameters.

A new azo-chromophore group containing a hydrazine-Schiff base compound, 2-[(E)-hydrazinylidenemethyl]-6-methoxy-4-[(E)-phenyldiazenyl]phenol, was synthesized and structurally characterized by single crystal X-ray diffraction study. The compound was found to crystallise in orthorhombic crystal system with Pca2(1) space group. In the structure, the molecule exhibits a phenol-imine intramolecular hydrogen bond and the NH2 group also involves in intermolecular hydrogen bonding with one of the nitrogen atom of the azo group (–NN–) forming a 1D zigzag chain. Computational studies were performed on the titled compound and its tautomers. As computationally, this compound and its tautomers were optimized by using M062X/6-311G(d,p) level. According to thermodynamic parameters, the most stable tautomer was found to be azo-enol form. This result was then taken into account and spectral studies, which are IR, UV–Vis and NMR spectra, of this compound were performed and examined in detail. All calculations were performed at gas phase (ε = 1.000), 2-propanol (ε = 19.264), 1,2-ethanediol (ε = 40.245), water (ε = 78.355), formamide (ε = 108.940) and N-methylformamide-mixture (ε = 181.560).

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