A determination of the structure of the title compound, C3H7NO2, leads to an accurate description of its molecular dimensions and crystal packing. As in the structure of the L-isomer, the molecules aggregate into alternating layers, each consisting of only one type of isomer. The molecules in each layer are interconnected through head-to-tail sequences generated by a cell translation and a 2(1) screw axis. Adjacent layers are interconnected by head-to-tail sequences generated by a glide plane.

In the title compound, C5H11NO2S, the conformation of the terminal meth­yl C atom with respect to the β‐C atom is trans. The crystal structure is stabilized by a network of characteristic head‐to‐tail dl1 and dl2 sequences.

Key indicatorsSingle-crystal X-ray study T = 293 K Mean '(C±C) = 0.003 A Ê R factor = 0.028 wR factor = 0.078 Data-to-parameter ratio = 7.2 For details of how these key indicators were automatically derived from the article, see

No abstract

In the title compound, C2H6NO2+.C2HO4-, the glycine molecule exists in the cationic form and the oxalic acid molecule in the mono-ionized state. The molecules aggregate into alternate columns of glycinium and semi-oxalate ions. The structure is stabilized by an extensive network of hydrogen bonds.

In the title compound, C5H12NO2S+·C4H3O4−, the me­thionine mol­ecule exists in the cationic form and the maleic acid mol­ecule in the mono‐ionized state. In the semi‐maleate ion, there is an asymmetric intramolecular hydrogen bond between the carboxy OH group and an O atom of the other carboxyl­ate group. There are no direct hydrogen‐bonded interactions among the semi‐maleate anions.

In the title salt, C(5)H(10)NO(2)(+).C(4)H(5)O(6)(-), proline exists as a cation and the tartaric acid as a semi-tartrate anion. The semi-tartrate ions form hydrogen-bonded strings along the c axis. These strings are interconnected through the proline molecules, forming a layered network parallel to the bc plane. The proline molecules, however, do not directly interact among themselves, except for a weak C-H.O hydrogen bond.

Key indicatorsSingle-crystal X-ray study T = 293 K Mean '(C±C) = 0.004 A Ê R factor = 0.035 wR factor = 0.106 Data-to-parameter ratio = 7.9For details of how these key indicators were automatically derived from the article, see