The structural behavior of perdeuterated, 11B-enriched ammonia borane, ND311BD3, was investigated by neutron powder diffraction measurements collected over the temperature range from 15 to 340 K and by molecular dynamics simulation. In the low temperature orthorhombic phase, the progressive displacement of the borane group under the amine group was observed leading to the rotation of the B-N bond parallel to the c-axis. The structural phase transition at 225 K is marked by dramatic change in the dynamics of both the amine and borane group that is problematic to extract from the metrics provided by Rietveld analysis of the NPD data alone but is evident in the molecular dynamics simulation and other spectroscopic evidence. This study highlights the valued added by complimentary experimental approaches and coupled computational studies.
Revised: June 28, 2010 |
Published: April 17, 2009
Citation
Hess N.J., G.K. Schenter, M.R. Hartman, L.L. Daemen, T.E. Proffen, S.M. Kathmann, and C.J. Mundy, et al. 2009.Neutron Powder Diffraction and Molecular Simulation Study of the Structural Evolution of Ammonia Borane from 15 to 340 K.Journal of Physical Chemistry A 113, no. 9:5723-5735.PNNL-SA-63995.doi:10.1021/jp900839c