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Title: The hydrated proton H/sup +/(H/sub 2/O)/sub n/. V. Observation of two diaquohydrogen ions, (D/sub 2/OxDxOD/sub 2/)/sup +/, in 5-sulphosalicylic acid dideuterate. A neutron diffraction study

Journal Article · · J. Chem. Phys.; (United States)
OSTI ID:7125055

The crystal and molecular structure of 5-sulphosalicylic acid dideuterate has been studied using three-dimensional single crystal neutron diffraction data. The triclinic unit cell, space group P1, contains two formula units, with dimensions a=7.028(5), b=7.007(5), c=11.678(8) A, ..cap alpha..=71.49(4), ..beta..=94.07(2), and ..gamma..=109.35(2) degree. A total of 2883 unique reflections were collected and full matrix least-squares refinement on F/sub 0/ /sup 2/ yielded an R=0.079. Two almost identical D/sub 5/O/sub 2//sup +/ cations were found, and both reside on centers of symmetry, suggesting that the cations are best formulated as (D/sub 2/OxDxOD/sub 2/)/sup +/ species. The bridging deuterium atoms have their largest vibrational amplitudes along the O--O direction, which is indicative of a broad--flat anharmonic single-minimum potential energy well. The slight deviations from this direction are correlated with the terminal oxygen atom vibrations. X-ray versus neutron difference density maps show pronounced polarization of the C--H and O--D bonds. (AIP)

Research Organization:
Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439
OSTI ID:
7125055
Journal Information:
J. Chem. Phys.; (United States), Vol. 66:4
Country of Publication:
United States
Language:
English