The organic component of the title compound, C22H20N2O5·2H2O, exhibits approximate but noncrystallographic mirror symmetry. The molecules of the organic component are linked by a combination of one O-H...O hydrogen bond and two N-H···O hydrogen bonds to form sheets containing R2(2)(8), R2(2)(16) and R6(6)(40) rings. These sheets are linked into a continuous three-dimensional framework structure by cyclic centrosymmetric R4(2)(8) water tetramers. Comparisons are made with some simpler analogues.
Keywords: crystal structure; cyclic water tetramers; hydrogen bonding.