Crystal structures of N(2),N(3),N(5),N(6)-tetra-kis-(pyridin-2-ylmeth-yl)pyrazine-2,3,5,6-tetra-carboxamide and N(2),N(3),N(5),N(6)-tetra-kis-(pyridin-4-ylmeth-yl)pyrazine-2,3,5,6-tetra-carboxamide.

The title compounds, C32H28N10O4· unknown solvent, (I), and C32H28N10O4, (II), are pyrazine-2,3,5,6-tetra-carboxamide derivatives. In (I), the substituents are (pyridin-2-ylmeth-yl)carboxamide, while in (II), the substituents are (pyridin-4-ylmeth-yl)carboxamide. Both compounds crystallize in the monoclinic space group P21/n, with Z' = 1 for (I), and Z' = 0.5 for (II). The whole mol-ecule of (II) is generated by inversion symmetry, the pyrazine ring being situated about a center of inversion. In (I), the four pyridine rings are inclined to the pyrazine ring by 83.9 (2), 82.16 (18), 82.73 (19) and 17.65 (19)°. This last dihedral angle involves a pyridine ring that is linked to the adjacent carboxamide O atom by an intra-molecular C-H⋯O hydrogen bond. In compound (II), the unique pyridine rings are inclined to the pyrazine ring by 33.3 (3) and 81.71 (10)°. There are two symmetrical intra-molecular C-H⋯O hydrogen bonds present in (II). In the crystal of (I), mol-ecules are linked by N-H⋯O and N-H⋯N hydrogen bonds, forming layers parallel to (10-1). The layers are linked by C-H⋯O and C-H⋯N hydrogen bonds, forming a three-dimensional framework. In the crystal of (II), mol-ecules are linked by N-H⋯N hydrogen bonds, forming chains propagating along the [010] direction. The chains are linked by a weaker N-H⋯N hydrogen bond, forming layers parallel to the (101) plane, which are in turn linked by C-H⋯O hydrogen bonds, forming a three-dimensional structure. In the crystal of compound (I), a region of disordered electron density was treated with the SQUEEZE routine in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9-18]. Their contribution was not taken into account during refinement. In compound (II), one of the pyridine rings is positionally disordered, and the refined occupancy ratio for the disordered Car-Car-Npy atoms is 0.58 (3):0.42 (3).