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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

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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.

Cati Dilovan S DS Stoeckli-Evans Helen H

Acta crystallographica. Section E, Crystallographic communications 20170131 Pt 2

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). T ...[more]

PMID: 28217363

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Project description:Two polymorphs of the title tetra-kis-substituted pyrazine carb-oxy-lic acid, 3,3',3'',3'''-{[pyrazine-2,3,5,6-tetra-yltetra-kis-(methyl-ene))tetra-kis-(sulfanedi-yl]}tetra-propionic acid, C20H28N2O8S4, (H4L1), have been obtained, H4L1_A and H4L1_B. Each structure crystallized with half a mol-ecule in the asymmetric unit of a triclinic P unit cell. The whole mol-ecules are generated by inversion symmetry, with the pyrazine rings being located about inversion centers. The crystals of H4L1_B were of poor quality, but the X-ray diffraction analysis does show the change in conformation of the -CH2-S-CH2-CH2- side chains compared to those in polymorph H4L1_A. In the crystal of H4L1_A, mol-ecules are linked by two pairs of O-H⋯O hydrogen bonds, enclosing R 2 2(8) ring motifs forming layers parallel to plane (100), which are linked by C-H⋯O hydrogen bonds to form a supra-molecular framework. In the crystal of H4L1_B, mol-ecules are also linked by two pairs of O-H⋯O hydrogen bonds enclosing R 2 2(8) ring motifs, however here, chains are formed propagating in the [001] direction and stacking up the a-axis. Reaction of H4L1 with Hg(NO3)2 in the presence of a potassium acetate buffer did not produce the expected binuclear complex, instead crystals of a potassium-organic framework were obtained, poly[(μ-3-{[(3,5,6-tris-{[(2-carb-oxy-eth-yl)sulfan-yl]meth-yl}pyrazin-2-yl)meth-yl]sulfan-yl}propano-ato)potassium], [K(C20H27N2O8S4)] n (KH3L1). The organic mono-anion possesses inversion symmetry with the pyrazine ring being located about an inversion center. A carb-oxy H atom is disordered by symmetry and the charge is compensated for by a potassium ion. A similar reaction with Zn(NO3)2 resulted in the formation of crystals of a dipotassium-organic framework, poly[(μ-3,3'-{[(3,6-bis-{[(2-carb-oxy-eth-yl)sulfan-yl]meth-yl}pyrazine-2,5-di-yl)bis(methyl-ene)]bis-(sulfanedi-yl)}dipropionato)dipotassium], [K2(C20H26N2O8S4)] n (K2H2L1). Here, the organic di-anion possesses inversion symmetry with the pyrazine ring being located about an inversion center. Two symmetry-related acid groups are deprotonated and the charges are compensated for by two potassium ions.

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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.

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