STRUCTURE OF CHOLINE PICRATE

C5H14NO+.C6H2N3O7-, M(r) = 332.2, monoclinic, P2(1)/n, a = 6.7895 (9), b = 22.054 (2), c 9.713 (i) angstrom, beta = 103.50 (1)-degrees, V = 1414.2 (5) angstrom3, Z 4, D(x) (105 K) = 1.561 Mg m-3, m.p. (hot-stage microscope) 516-518 K (corrected), lambda(Cu K-alpha) = 1.5418 angstrom, mu = 1.116 mm-1, F(000) = 696, T -105 K, R = 0.039 for 2581 observed reflections [I greater-than-or-equal 3-sigma(I)]. The choline ion adopts a folded conformation, tau(O-C-C-N) = +/- 90.1 (1)-degrees. Strands of choline ions are formed via C...O contacts of length 3.305 (2) angstrom [C9...O4 (x - 1, y, z)] oriented along the a axis. Only weaker contacts are observed between parallel strands, which together form layers perpendicular to the b axis. The picrate ions are stacked in columns along the a axis with an average distance of 3.263 angstrom between the benzene rings. The parallel columns of picrate ions form layers perpendicular to the b axis. The picrate ions are not stacked exactly on top of each other; the shift releaves strain. One nitro group overlaps the neighbouring benzene ring. The other nitro group close to the phenolate O atom makes an angle of 40.35 (4)-degrees to the plane of the benzene ring, and is found on the outside of the column. The choline hydroxy group donates a hydrogen bond [O4...O21 2.781 (1) angstrom] to the phenolate O atom of the picrate ion. Many weak contacts, shorter than the sum of the van der Waals radii, are found involving the quaternary ammonium group and O atoms of the picrate ion.