L-Methioninium chloride and L-selenomethioninium chloride at 103 K.

The crystal structures of the title compounds, (S)-1-carboxy-3-(methylsulfanyl)propanaminium chloride, C(5)H(12)NO(2)S(+).Cl(-), and (S)-1-carboxy-3-(methylselanyl)propanaminium chloride, C(5)H(12)NO(2)Se(+).Cl(-), are isomorphous. The protonated L-methionine and L-selenomethionine molecules have almost identical conformations and create very similar contacts with the Cl(-) anions in the crystal structures of both compounds. The amino acid cations and the Cl(-) anions are linked viaN-H...Cl(-) and O-H...Cl(-) hydrogen bonds.