Crystal Structure of the Dietary Supplement Ferrous Glycine Sulfate

The crystal structure of ferrous glycine sulfate (a ferroglycine sulfate complex with chemical formula FeSO₄(C₂H₅NO₂), a compound extensively used as an iron dietary supplement, was refined from synchrotron X‐ray powder diffraction data. The crystal structure of an (so‐far unreported) isostructural manganese analogue was also structurally detailed by a Rietveld refinement against the corresponding X‐ray powder diffraction pattern. All studied compounds crystallize in the monoclinic P2₁ space group, building layers of metal cations coordinated by the oxygen atoms of sulfate groups and glycine ligands. Neighboring layers are parallel packed, bonded by hydrogen bonds. The coordination polyhedra around the cations can be regarded as distorted and elongated octahedral, presumably due to severe strains present in the crystal structure of the layers.