N,N′-(Pyridine-2,6-di­yl)dibenzamide

The mol­ecule of the title compound, C₁₉H₁₅N₃O₂, is completed by the application of crystallographic twofold symmetry, with the pyridine N atom lying on the rotation axis. The mol­ecular structure is approximately planar, the dihedral angle between the mean planes of the pyridine and benzene rings being 7.53 (11)°. In the crystal, N—H...O hydrogen bonds link the mol­ecules into a two-dimensional array perpendicular to the c axis.

Bis(L-serinium) oxalate dihydrate: polymorph II

A corrected and improved structure of the polymorph II of 2C₃H₈NO₃⁺·C₂O₄²⁻·2H₂O, based on single-crystal data, is presented. The structure is refined with anisotropic displacement parameters for all non-H atoms and all H atoms are located. Due to the charged moieties, the structure is classified as a mol­ecular salt. Inter­molecular O—H...O⁻, O—H...O and N⁺—H...O⁻hydrogen bonds link the components of the structure. The L-serinium cations and oxalate anions form a network of channels in [100] direction, filled with the water molecules of crystallization. The dihedral angle between the CO₂ units of the oxalate dianion is 10.2 (3)°