Molecular Structure and Density Functional Theory Calculations of 3-(3-Nitrothien-2-yl)indole: Structural and Vibrational Analysis

Abstract

An X-ray diffraction study along with crystal supramolecular analysis of 3-(3-nitrothien-2-yl)indole, I, were carried out. The crystals are orthorhombic; C₁₂H₈N₂O₂S; M = 244.26; a = 13.3286 (6) Å, b = 7.5109 (4) Å, c = 21.8144 (9) Å; α = β = γ = 90°; V = 2183.83 (18) Å³, d _c = 1.486 g/cm³, Z = 8, space group Pbca. The crystal structure of the title compound consists of two planar rings, the indole ring and the substituted thiophene ring. The inter-planar angle between the indole ring system and thiophene ring is 34.39°. The dihedral angle of the NO₂ plane and the thiophene plane is 5.09°. The crystal packing shows crystal supramolecularity in which molecules are connected via different C–H···O, N–H···C(π) intermolecular interactions with edge-to-face and offset-face-to-face aryl···aryl, interactions consolidating three-dimensional network. The molecular geometry and vibrational frequencies of (C₁₂H₈N₂O₂S) in the ground state have been calculated by using density functional method (DFT/B3LYP) with 6-311++G(d,p) basis set. The optimized geometric bond lengths and bond angles and IR stretching frequencies obtained show good agreement with the experimental data.

Graphical Abstract

The crystal structure reveals different crystal supramolecularity motifs via C–H···O, N–H···C(π) and edge-to-face and offset-face-to-face aryl···aryl, interactions consolidating three-dimensional network. Density functional method (DFT/B3LYP) with 6-311++G(d,p) basis set of the obtained optimized geometric and IR stretching frequencies show good agreement with the experimental data.