COMPLEXES OF THE PROTON SPONGE 1,8-BIS(DIMETHYLAMINO)NAPHTHALENE (DMAN) .4. STRUCTURE OF [DMANH]2+BULLET[SQUARATE]2- TETRAHYDRATE AT 100-K

Bis[(8-dimethylamino-1-naphthyl)dimethylammonium] 3,4-dioxocyclobut-1-ene-1,2-diolate tetrahydrate, 2C14H19N2+ . C4O42- . 4H2O, M(r) = 614.74, orthorhombic, Cmc2(1), a = 11.2191 (4), b = 15.9824 (5), c = 17.7311 (7) angstrom, V = 3179.3 (2) angstrom3, Z = 4, D(x) = 1.284 g cm-3, lambda(Mo K-alpha) = 0.71073 angstrom, mu = 1.0 cm-1, F(000) = 1320, T = 100 K, R = 0.033 for 1790 reflections with I > 2.5-sigma(I). The asymmetric unit consists of two half DMANH+ cations, one half squarate anion and four half water molecules. The crystallographic mirror plane bisects the two independent DMANH+ cations through the central C-C bond and contains the squarate anion and the four water molecules. The H atoms in the two [N-H...N]+ intramolecular hydrogen bonds are disordered and located at about 0.35 angstrom from the mirror plane.