Crystal structure of 2,5-di-hydroxy-terephthalic acid from powder diffraction data.

The crystal structure of anhydrous 2,5-dhy-droxy-terephthalic acid, C8H6O6, was solved and refined using laboratory X-ray powder diffraction data, and optimized using density functional techniques. The published structure of 2,5-di-hydroxy-terephthalic acid dihydrate was also optimized. The carb-oxy-lic acid groups form strong hydrogen bonds, which form centrosymmetric rings with graph set R 2 2(8). These hydrogen bonds link the mol-ecules into chains along [011]. There is an intra-molecular O-H⋯O hydrogen bond between the hydroxyl group and the carbonyl group of the carb-oxy-lic acid. The hydrogen bonding in the dihydrate is very different. Although the intra-molecular hy-droxy/carb-oxy-lic acid hydrogen bond is present, the water mol-ecule acts as an acceptor to the carb-oxy-lic acid and a donor to two other oxygen atoms. The carb-oxy-lic acid groups do not inter-act with each other directly.

Structures of dicobalt and dinickel 4,4'-bi-phenyldi-carboxyl-ate di-hydroxide, M 2(O2CC6H4C6H4CO2)(OH)2, M = Co and Ni, and di-ammonium 4,4'-bi-phenyldi-carboxyl-ate from powder diffraction data.

The triclinic structures of poly[(µ4-4,4'-bi-phenyldi-carboxyl-ato)di-µ-hydroxido-dicobalt], [Co2(C14H8O4)(OH)2] n , and poly[(µ4-4,4'-bi-phenyldi-carboxyl-ato)di-µ-hydroxido-dinickel], [Ni2(C14H8O4)(OH)2] n , were established using laboratory X-ray powder diffraction data. These structures, as well as that of poly[(µ4-4,4'-bi-phenyldi-carboxyl-ato)di-µ-hydroxido-dimanganese], [Mn2(C14H8O4)(OH)2] n , were optimized using density functional techniques. The structure of di-ammonium 4,4'-bi-phenyldi-carboxyl-ate, 2NH4 +·C14H8O4 2-, was also solved using laboratory powder data. The Mn and Co compounds are isostructural: the octa-hedral MO6 groups share edges to form chains running parallel to the c-axis. These chains share corners (OH groups) to link into layers lying parallel to the bc plane. The hydroxyl groups do not participate in hydrogen bonds. The structure of (NH4)2BPDC consists of alternating layers of BPDC and ammonium ions lying parallel to the ab plane. Each hydrogen atom of the ammonium ions in (NH4)2BPDC participates in a strong N-H⋯O hydrogen bond.

Crystal structures of dimetal terephthalate di-hydroxides, M 2(C8H4O4)(OH)2 (M = Co, Ni, Zn) from powder diffraction data and DFT calculations.

The crystal structure of poly[di-hydroxido(µ6-terepthalato)dizinc], [Zn2(C8H4O4)(OH)2] n , was solved and refined using synchrotron powder data, and the structures of the isostructural Co and Ni analogues were refined using laboratory powder X-ray data. The structure of [Co2(C8H4O4)(OH)2] n has been reported previously in space group C2/m, which yields disordered terephthalate anions. Doubling the c-axis of that cell results in an ordered model in space group C2/c. The octa-hedral MO6 coordination polyhedra of the metal cations share edges, forming chains running parallel to the b-axis direction. These chains share corners (hydroxyl groups), forming layers lying perpendicular to the a-axis direction.