Low melting point organic crystal structures by high-resolution neutron powder diffraction: The structure determination of acetaldehyde

High-resolution neutron powder diffraction is particularly suited for structure solution and refinement of low melting point organic crystals. Whereas materials that are gas or liquid at ambient temperature pose practical difficulties both in growing single crystals and also in preparing small-volume samples for X-ray studies that exhibit a good powder average, low-temperature sample preparation and data collection for neutron powder diffraction experiments is relatively straightforward. These practical advantages and high-resolution instrumentation are a powerful combination that enable the precise and accurate determination of moderately complex molecular crystal structures. The structure solution and phase behaviour of acetaldehyde (m.p. 152 K) is described.