Synthesis, Crystal Structure, Hirshfeld Surface and Computational Analysis of Bis-[2-(3,4-dihydroxyphenyl)-4,5-diphenyl-1H-imidazol-3-ium] Oxalate Ethanol Solvate

Bis-[2-(3,4-dihydroxyphenyl)-4,5-diphenyl-1H-imidazol-3-ium] Oxalate ethanol solvate crystal has been isolated from slow solvent evaporation method and the structure was characterized by FT-IR, NMR and Single crystal XRD. The compound crystallizes in the triclinic space group P \(\overline{1 }\) with a = 7.7925(16), b = 10.716(3), c = 13.952(3), α = 106.545(5), β = 97.514(5), γ = 110.152(5), V = 1014.0(4) Å3 and Z = 1. The single crystal X-ray data of the compound confirms two proton transfers from an oxalic acid to the pyrimidine-type-nitrogen of two separate imidazole rings. The structure and symmetry of the Imidazolium Oxalate is dictated by N–H⋯O and O–H⋯O hydrogen bonding interactions and are confirmed by hydrogen bonding analysis and hirshfeld surface analysis. The partial double bond character in the imidazolium ring confirms delocalization across the molecular framework. The partial double bond character of the C–O bonds also confirms delocalization in the oxalate anion. The crystal is 3-dimensional structure, with crystal growth in all the crystallographic axis. Computational analysis [DFT, B3LYP/6-311G(d,p)] reveals close correlation of the constrained optimized structure with the experimental data.

Graphical Abstract

Imidazolium oxalate crystal form by the protonation of Imidazole compound and complex formation with oxalate ion.