Crystal structure of a second triclinic polymorph of 2-methyl-pyridinium picrate.

ABSTRACT: The title mol-ecular salt, C6H8N(+)·C6H2N3O7 (-) (systematic name: 2-methyl-pyridinium 2,4,6-tri-nitro-phenolate), 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 ?-? stacking between the 2-methyl-pyridinium 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 inter-esting that the unit-cell lengths are almost identical for the two polymorphs, although the inter-axial angles are quite different.

SUBMITTER: Gomathi J 

PROVIDER: S-EPMC4645006 | biostudies-other | 2015 Nov

REPOSITORIES: biostudies-other