Qualitative and Quantitative Study of Intermolecular Interactions in Imidazo[2,1-b] [1,3,4] Thiadiazoles

The crystal structures of three Imidazo [2, 1-b] [1, 3, 4] thiadiazole derivatives were determined by single crystal x-ray diffraction method. All compounds are crystallized under monoclinic crystal system, P2(1) space group. In solid-state, the crystal structures are primarily stabilized by C-H horizontal ellipsis O hydrogen bonds. The chloro and bromo substituted structures exhibits sigma hole involved S horizontal ellipsis O and S horizontal ellipsis N non-bonding interactions. A detailed analysis of crystal packing with the evaluation of interaction energies of molecular pairs extracted from both PIXEL and quantum chemical methods were presented in detail. In addition, Hirshfeld 2D fingerprint plots are used to estimate intermoleular interactions quantitatively. The iso-structurality present in the crystal packing was investigated using XPAC analysis. The molecular electrostatic potential (MEP) was mapped to identify the reaction sites of the molecules. Further nonlinear optical properties are calculated using Density functional theory.

Automated summary

The crystal structures of three Imidazo [2, 1-b] [1, 3, 4] thiadiazole derivatives were determined by single crystal x-ray diffraction method, with C-H... O hydrogen bonds playing a key role in stabilizing the crystal structures. Analyzing the crystal packing, interaction energies of molecular pairs, molecular electrostatic potential, and nonlinear optical properties shed light on the intermolecular interactions and structural properties of the compounds.