title: Variable-temperature neutron diffraction studies of the short, strong hydrogen bonds in the crystal structure of pyridine-3,5-dicarboxylic acid.
abstract: Pyridine-3,5-dicarboxylic acid has been studied by single-crystal neutron diffraction at 15 and 296 K. Pyridine-3,5-dicarboxylic acid, in which the carboxylic acid protons have been replaced by deuterons, has also been studied at 15, 150 and 296 K. The protonated structure contains a short N...H...O hydrogen bond [N...O 2.523 (2) Angstrom at 15 K]. Temperature-dependent proton migration occurs where the N--H distance in the hydrogen bond changes from 1.213 (4) Angstrom at 15 K to 1.308 (6) Angstrom at 300 K. In the deuterated structure the overall hydrogen-bond length increased [N...O 2.538 (3) Angstrom at 15 K] and the magnitude of the migration increased so that the N--D distance changes from 1.151 (3) Angstrom at 15 K to 1.457 (4) Angstrom at 300 K.
authors.affiliation: Institut Laue Langevin, 6 Rue Jules Horowitz, BP156, 38042 Grenoble, CEDEX 9, France. j.a.cowan@dl.ac.uk
authors.forename: John A
authors.initials: JA
authors.lastname: Cowan
authors.forename: Judith A K
authors.initials: JA
authors.lastname: Howard
authors.forename: Garry J
authors.initials: GJ
authors.lastname: McIntyre
authors.forename: Samuel M F
authors.initials: SM
authors.lastname: Lo
authors.forename: Ian D
authors.initials: ID
authors.lastname: Williams