A redetermination of the structure of poly[[μ4-(R)-2-ammonio-3-sulfonato­propano­ato]aqua­sodium], originally reported as poly[[μ7-l-cysteato(2−)]disodium]

The structure originally reported as poly[[μ(7)-l-cysteato(2-)]disodium], [Na(2)(C(3)H(5)NO(5)S)](n) [Liu (2002). Acta Cryst. E67, m1346-m1347], has been redetermined with one of the sodium atoms replaced with a water mol-ecule and an additional proton attached to the amine group, resulting in the revised formula [Na{CO(2)CH(CH(2)SO(3))NH(3)}(H(2)O)](n). The agreement index, wR, has been reduced from 0.159 to 0.087 and the global instability index from 0.56 vu (valence units) to the acceptable value of 0.11 vu.