Stable conformations of N,N,N′,N′- tetraisopropylthiuram disulphide and monosulphide found in low temperature 1H N.m.r. spectra

¹H N.m.r. spectra of N,N,N′,N′-tetraisopropylthiuram disulphide and monosulphide in CS₂ suggested that internal rotations both around the carbamate C? N and isopropyl–nitrogen bonds are restricted at low temperatures. As a result, both compounds exist as two dl pairs of isomers with respect to rotation around the isopropyl–nitrogen bond. The spectra further suggest that one pair of the isomers is subdivided into two sets of dl pairs, possibly owing to the restriction of torsion of the two carbamate planes with respect to each other. Possible conformations of these three dl pairs of isomers are proposed, and the assignments of each proton signal are described.