The title compound, (C7H9N2O2)2[HgCl4], self-assembles into cationic organic bilayers containing the 2-methyl-4-nitroanilinium
cations, sandwiched between anionic inorganic
layers built up by the distorted tetrahedral [HgCl4]2 groups. The organic sheets are interlinked through weak C—H...O hydrogen bonds, while they interact with the anionic part via
strong charge-assisted N+—H...Cl—Hg hydrogen bonds. The [HgCl4]2 anions are bisected by a mirror plane passing through the metal and two of the chloride ions.