Precision neutron diffraction structure determination of protein and nucleic acid components. XVII. Molecular and crystal structure of the amino acid glycine hydrochloride

Abstract

The amino acid salt glycine hydrochloride, H3N+⋅CH2⋅COOH⋅Cl−, crystallizes in the space group P21/c, a=7.117(2) Å, b=5.234(2) Å, c=13.745(3) Å, β=97.25(1) °. The crystal structure has been refined from three-dimensional neutron diffraction data to a final R value based on F2 of 0.058. Estimated standard deviations in bond distances and angles are approximately 0.002 Å and 0.2°, respectively. There is a network of hydrogen bonds with the chloride ions linking three neighboring glycines to form layers parallel to the ab plane. One ammonium group hydrogen is involved in two weak electrostatic interactions; these interactions join the single layers to form parallel double layers but are probably too weak to be termed hydrogen bonds.