AbstractDeuteration of 2‐phenylthiazolidine, and its complexation with the shift reagent tris(1,1,1,2,2,3,3‐heptafluoro‐7,7‐dimethyl‐4,6‐octanedionato)europium, have been used to study the signals and conformation of the heterocyclic protons and to interpret the 1H NMR spectrum of this 2‐substituted thiazolidine.