Accurate positional and thermal parameters of hexamethylenetetramine from K-shell X-ray diffraction data

Geometric and thermal parameters for hexamethylenetetramine have been determined from 95 unique reflections (Mo Kα, graphite monochromator) in the sin θ/λ range 0.65-1.10 Å^-1. Both standard (second cumulant) anisotropic thermal parameters and third cumulant parameters as well as positional parameters for C and N are in excellent agreement with the corresponding neutron parameters. H atom parameters were not determined from the X-ray data. The estimated standard deviations for the X-ray parameters are generally one fifth (or less) of those for the neutron parameters. This study shows that with X-ray data it is possible to determine geometric and thermal parameters free of effects from valence electron asphericity.