Date Published: June 01, 2012
Publisher: International Union of Crystallography
Author(s): Kevin Lamberts, Ulli Englert.
The crystal structure of dl-alanine hydroiodide (1-carboxyethanaminium iodide), C3H8NO2+·I−, is that of an organic salt consisting of N-protonated cations and iodide anions. The compound features homochiral helices of N—H⋯O hydrogen-bonded cations in the  direction; neighbouring chains are related by crystallographic inversion centers and hence show opposite chirality. The iodide counter-anions act as hydrogen-bond acceptors towards H atoms of the ammonium and carboxy groups, and cross-link the chains along . Thus, an overall two-dimensional network is formed in the ab plane. No short contacts occur between iodide anions.
For related structures of l-alanine hydrochloride, see: Di Blasio et al. (1977 ▶), d-alanine alaninium bromide, see: Fischer (2006 ▶), l-alanine hydrochloride monohydrate, see: Yamada et al. (2008 ▶) and dl-alanine hydrochloride, see: Trotter (1962 ▶).