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Crystal structure of a second triclinic polymorph of 2-methylpyridinium picrate
The title molecular salt, C(6)H(8)N(+)·C(6)H(2)N(3)O(7) (−) (systematic name: 2-methylpyridinium 2,4,6-trinitrophenolate), crystallizes with two cations and two anions in the asymmetric unit. In the crystal, the cations are linked to the anions via bifurcated N—H⋯(O,O) hydrogen bonds, generating...
Autores principales: | , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
International Union of Crystallography
2015
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4645006/ https://www.ncbi.nlm.nih.gov/pubmed/26594559 http://dx.doi.org/10.1107/S205698901501912X |
Sumario: | The title molecular salt, C(6)H(8)N(+)·C(6)H(2)N(3)O(7) (−) (systematic name: 2-methylpyridinium 2,4,6-trinitrophenolate), crystallizes with two cations and two anions in the asymmetric unit. In the crystal, the cations are linked to the anions via bifurcated N—H⋯(O,O) hydrogen bonds, generating R (1) (2)(6) graph-set motifs. Numerous C—H⋯O hydrogen bonds are observed between these cation–anion pairs, which result in a three-dimensional network. In addition, weak aromatic π–π stacking between the 2-methylpyridinium rings [inter-centroid distance = 3.8334 (19) Å] and very weak stacking [inter-centroid distance = 4.0281 (16) Å] between inversion-related pairs of picrate anions is observed. The title salt is a second triclinic polymorph of the structure (also with Z′ = 2) reported earlier [Anita et al. (2006). Acta Cryst. C62, o567–o570; Chan et al. (2014 ▸). CrystEngComm, 16, 4508–4538]. In the title compound, the cations and anions display a chequerboard arrangement when viewed down [100], whereas in the first polymorph, (010) layers of alternating cations and anions are apparent in a [100] view. It is interesting that the unit-cell lengths are almost identical for the two polymorphs, although the inter-axial angles are quite different. |
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