STRUCTURE OF 8-DIMETHYLAMINO-1-DIMETHYLAMMONIONAPHTHALENE HYDROGEN SQUARATE

(8-Dimethylamino-1-naphthyl)dimethyl-ammoniun 2-hydroxy-3,4-dioxocyclobut-1-en-1-olate, C14H19N2+.C4HO4-, M(r) = 328.37 orthorhombic, Pbca, a = 18.319 (3), b = 14.868 (2), c = 12.219 (1) angstrom, V = 3328.1 (8) angstrom 3, Z = 8, D(x) = 1.311 g cm-3, lambda(Mo K-alpha) = 0.71073 angstrom, mu = 1.0 cm-1, F(000) = 1392, T = 150 K, R = 0.036 for 3003 observed reflections with I greater-than-or-equal-to 2.5-sigma(I). In the crystal structure of the title compound bis(dimethylamino)-naphthalene acts as a proton sponge by accepting a proton from squaric acid. In the 1-dimethylamino-8-dimethylammonionaphthalene cation a strong asymmetric intramolecular hydrogen bond is formed with N...N, N-H and N-H...N 2.583 (2), 1.08 (2) angstrom and 157 (2)-degrees respectively. The N-H donor also is involved in a weak interaction with a squarate carbonyl group. The hydrogen squarate anions form planar strongly hydrogen-bonded cyclic dimers across centers of inversion with O...O, O-H and O-H...O 2.477 (2), 0.97 (2) angstrom and 170 (2)-degrees respectively. In contrast to the free base which displays severe puckering of the aromatic system and opposite deviations of the N atoms of 0.40 angstrom from the best plane, the aromatic system including both N atoms of the cation is planar.