title: Structure of the sodium salt of 1,4,5,8-naphthalenetetracarboxylic acid 4,5-anhydride hydrate.
abstract: Sodium hydrogen 1,3-dioxo-1H,3H-naphtho[1,8-cd]pyran-6,7-dicarboxylate hydrate, Na[C14H5O7].H2O, Mr = 326.2, triclinic, P1, a = 9.520 (2), b = 9.549 (3), c = 7.860 (1) A, alpha = 105.88 (2), beta = 110.29 (1), gamma = 100.89 (2) degrees, V = 611.9 (3) A3, Z = 2, Dx = 1.77 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 1.67 cm-1, F(000) = 332, T = 295 K, R = 0.042 for 1665 unique reflections having I greater than 3 sigma I. The organic portion of this structure demonstrates near-C2 symmetry with a pseudo-twofold axis coincident with the central C-C naphthalene ring bond. The atoms of the naphthopyran three-ring system deviate by an average of 0.037 (19) A from the best least-squares plane through the three rings. Each of the carboxyl group planes is substantially inclined to the naphthopyran ring plane, the average dihedral angle measuring 62 (1) degree. The Na ion is coordinated by O atoms in a highly distorted octahedral geometry with a mean Na--O distance of 2.49 (12) A. A short hydrogen bond is formed between a carboxylic acid group and a carboxylate anion; the H...O(acceptor) distance is 1.35 (5) A and the O...O(acceptor) distance is 2.475 (3) A. The acid H-atom position is located asymmetrically with respect to the O atoms. The water H atoms are involved in unequal three-centered hydrogen bonds. The molecules are stacked such that the naphthopyran ring portion of the structure is nearly parallel to the ab cell face and the stacks are connected by the hydrogen bonds.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Chemistry, Ohio State University, Columbus 43210.
authors.forename: L J
authors.initials: LJ
authors.lastname: Fitzgerald
authors.forename: J C
authors.initials: JC
authors.lastname: Gallucci
authors.forename: R E
authors.initials: RE
authors.lastname: Gerkin
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003460:Crystallization; D006860:Hydrogen Bonding; D015394:Molecular Structure; D009281:Naphthalenes / Q000737:chemistry*; D011753:Pyrones / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D009281:Naphthalenes; D011753:Pyrones; C075326:1,4,5,8-naphthalene tetracarboxylic acid 4,5-anhydride