An oxonium hydrogen sulfate of 3a,6a‐diphenyl­glycoluril

In the title compound, (5‐oxo‐3a,6a‐diphenyl­perhydro­imidazo4,5‐d]imidazol‐2‐ylidene)oxonium hydrogen sulfate, C₁₆H₁₅N₄O₂⁺·HSO₄^?, the asymmetric unit contains a hydrogen sulfate anion and a 3a,6a‐diphenyl­glycoluril oxonium cation. The hydrogen sulfate anion is joined to the oxonium cation via a strong O—H?O hydrogen bond (H?O = 1.69 Å). The crystal packing is mainly dominated by inter­actions involving the hydrogen sulfate anion. The diphenyl­glycoluril oxonium cations also self‐assemble through N—H?O hydrogen bonds, forming mol­ecular chains along the 001] vector. Four intra­molecular C—H?N hydrogen bonds are observed, having an S(5) motif.