2-(3-Hydroxyphenyl)-4,5-diphenyl-1<i>H</i>-imidazol-3-ium hemioxalate ethanol monosolvate

In the title imidazolium oxalate solvate, C 21 H 17 N 2 O + 0.5C 2 O 4 2 C 2 H 6 O, the cation and the ethanol solvent molecule are located on general positions, whereas the complete oxalate ion is generated by a crystallographic centre of symmetry.The study confirms two proton transfers from oxalic acid to the pyrimidine-type N atoms of two separate imidazole rings.The extended structure features strong N-H O and O-H O hydrogen-bond interactions.