title: Structure of the adipate complex [Na2(C6H9O4)2(C6H10O4)].2H2O from neutron diffraction at 220 and 295 K.
abstract: The crystal structure of sodium hydrogen adipate-adipic acid (2/1) dihydrate, [Na2(C6H9O4)2(C6H10O4)].2H2O, Mr = 518.4, has been determined from neutron diffraction data collected at 220 and 295 K. Crystals are monoclinic, space group C2/m, with Z = 2. At 295 K, a = 9.378 (2), b = 13.379 (5), c = 10.247 (3) A, beta = 95.93 (3) degrees, V = 1278.8 (7) A3, Dn = 1.346, Dm = 1.348 (1) g cm-3 (in dibromomethane/bromobutane), lambda = 1.1588 (2) A, mu = 2.186 cm-1, F(000) = 176.4 fm, R(F2) = 0.108 for all 1995 nonequivalent reflections with sin theta/lambda less than 0.71 A-1. The crystal structure is similar at 220 K except for reduced nuclear mean-square displacements. Hydrogen adipate subunits (called A) are linked end-to-end in infinite chains by very short O...O (2.44 A) hydrogen bonds where the H nuclei are on centers of symmetry within the experimental error. The Na cation is octahedrally coordinated by O atoms from molecules A and also by non-ionized adipic acid molecules (called B). The B molecules have large mean-square nuclear displacements which are described in terms of anharmonicity and disorder.
authors.affiliation: Department of Crystallography, University of Pittsburgh, PA 15260.
authors.forename: Q
authors.initials: Q
authors.lastname: Gao
authors.forename: L
authors.initials: L
authors.lastname: Clancy
authors.forename: H P
authors.initials: HP
authors.lastname: Weber
authors.forename: B M
authors.initials: BM
authors.lastname: Craven
authors.forename: R K
authors.initials: RK
authors.lastname: McMullan
mesh_terms: D000272:Adipates / Q000737:chemistry*; D003460:Crystallization; D005583:Fourier Analysis; D015394:Molecular Structure; D009502:Neutrons; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D000272:Adipates; C071088:adipate-adipic acid; C029900:adipic acid