Orientational Disorder in Adamantane and Adamantanecarboxylic Acid

Edward O R Beake; Matthew G Tucker; Martin T Dove; Anthony E Phillips

doi:10.1002/cphc.201601219

Orientational Disorder in Adamantane and Adamantanecarboxylic Acid

Chemphyschem. 2017 Mar 3;18(5):459-464. doi: 10.1002/cphc.201601219. Epub 2017 Feb 7.

Authors

Edward O R Beake¹, Matthew G Tucker^{2

3}, Martin T Dove¹, Anthony E Phillips¹

Affiliations

¹ School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
² ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, OX11 0QX, UK.
³ Current address: Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA.

PMID: 28000340
DOI: 10.1002/cphc.201601219

Abstract

The molecular crystals adamantane, C₁₀ H₁₆ , and adamantanecarboxylic acid, C₁₀ H₁₅ COOH, undergo order-disorder phase transitions at 208 and 250 K, respectively. Reverse Monte Carlo refinement of total neutron scattering data collected from deuterated samples immediately above these phase transitions shows that the high-temperature phases are well described by models in which the adamantyl groups are disordered over two sites. No correlation between the orientations of neighbouring molecules is observed. These results demonstrate that the intermolecular potential energy of these materials depends strongly on the orientation of the reference molecule but only very weakly on the orientations of its neighbours.

Keywords: adamantane; orientational disorder; plastic crystals; reverse Monte Carlo; total neutron scattering.