Redetermined structure of β-dl-methionine at 105 K: an example of the importance of freely refining the positions of the amino-group H atoms

Abstract

Diffraction data were taken from the contribution named `β-dl-Methionine at 105 K′ by Alagar et al. [Acta Cryst. (2005). E61, o1165–o1167]. Refinement of the coordinates of the three amino H atoms, previously constrained to an idealized geometry, shows that the amino group is in fact rotated 13.5° from the perfectly staggered orientation. This apparently modest change has a profound impact on the calculated hydrogen-bond geometries.

Keywords

• hydrogen-bond geometry
• amino group
• refinement model
• β-DL-methionine
• crystal structure