Heterocyclic tautomerism: reassignment of two crystal structures of 2-amino-1,3-thia­zolidin-4-one derivatives

Two structures of 2-amino-1,3-thia­zolidin-4-one derivatives, deposited in the Cambridge Strutural Database (refcodes GACXOZ and HEGLUC), that undergo the phenomenon of proton amine-imine tautomerism are shown to exist in their crystal structures as the tautomer with the carbonyl-imine group in the five-membered heterocyclic ring and an exocyclic amine N atom, rather than the previously reported tautomer with a secondary amide group and an exocyclic imine N atom.