Structure and non-covalent interactions of (E,Z)3-benzoyl-1,5-bis(4-ethoxyphenyl)formazan: A crystallographic and DFT/TD-DFT study

Abstract

Formazans, an important class of compounds are known for their intense color and high complexing capability. Herein we report the synthesis and structure of 3-benzoyl-1,5-bis(4-ethoxyphenyl)formazan, compound 1 along with the detailed analysis of non-covalent interactions in its crystalline state. The chemical structure of compound 1 was characterized using various spectroscopic techniques and single-crystal X-ray diffraction. Compound 1 crystallizes in monoclinic, P 21/c space group with a single molecule in the asymmetric unit. The molecular structure of 1 was further investigated using DFT/TD-DFT methods at the CAM-B3LYP/6-31+G (d, p) level of theory. The ground state geometrical parameters along with NMR, vibrational and electronic absorption spectra calculated are in accordance with the experimental data. The spectral and theoretical results revealed that compound 1 exists as amine-imine tautomeric forms. Hirshfeld surface and fingerprint analysis were employed to explore the surface characteristics of the molecules in the crystal. Hirshfeld surface studies reflected that the molecular arrangement in the crystal is stabilized by various intermolecular interactions such as hydrogen bonding and π - π stacking. Among various interactions, the dispersion forces play a dominant role in crystal packing as evident from the molecular interaction energy calculations.