organic compounds
Open access
The asymmetric unit of the title compound, C9H9N2+·C4H3O4−·0.5C4H4O4, consists of one 2-phenylimidazolium cation, one hydrogen fumarate anion and half a fumaric acid molecule, which lies on an inversion center. N—HO and O—HO hydrogen bonds connect the cations, anions and fumaric acid molecules into sheets parallel to the (102) plane.