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

摘要

Diffraction data were taken from the contribution named ‘β-dl-Me­thio­nine at 105 K′ by Alagar et al. [Acta Cryst. (2005). E>61, 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.