Crystal structures of N²,N³,N⁵,N⁶-tetra-kis-(pyridin-2-ylmeth-yl)pyrazine-2,3,5,6-tetra-carboxamide and N²,N³,N⁵,N⁶-tetra-kis-(pyridin-4-ylmeth-yl)pyrazine-2,3,5,6-tetra-carboxamide.

ABSTRACT: 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 C_ar-C_ar-N_py atoms is 0.58?(3):0.42?(3).

SUBMITTER: Cati DS 

PROVIDER: S-EPMC5290586 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature