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Reorientational Dynamics of the Dodecahydro-Closo-Codecaborate Anion in Cs2B12H12

Published

Author(s)

Kristina Verdal, Terrence J. Udovic, John J. Rush, Ronald L. Cappelletti, Wei Zhou

Abstract

Rapid reorientational motions of the B12H122- icosahedral anion, a key intermediate in borohydride dehydrogenation, are revealed by quasielastic neutron scattering (QENS) measurements of Cs2B12H12 between 430 K and 530 K. At 430 K, over the range of momentum transfers collected, the elastic incoherent structure factor is consistent with a model for reorientation about a single molecular axis. At temperatures of 480 K and higher, however, the reorientation seems to proceed by dynamically similar, independent jumps about two axes: the three-fold and five-fold rotational axes, preserving crystallographic order. Although neutron vibrational spectra demonstrate that the anion torsional modes soften dramatically with increasing temperature, the QENS-derived activation energy for reorientation clearly shows that the anions are not undergoing random rotational diffusion.
Citation
Journal of Physical Chemistry Letters
Volume
226
Issue
14

Keywords

hydrogen storage, B12H12, quasielastic neutron scattering, hydrogen dynamics

Citation

, K. , Udovic, T. , Kasianowicz, J. , Cappelletti, R. and Zhou, W. (2011), Reorientational Dynamics of the Dodecahydro-Closo-Codecaborate Anion in Cs<sub>2</sub>B<sub>12</sub>H<sub>12</sub>, Journal of Physical Chemistry Letters, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=907876 (Accessed April 12, 2024)
Created March 17, 2011, Updated February 19, 2017