The zwitterionic title compound, C23H42N2O2S·4H2O, crystallized as a tetrahydrate from a solution of N-[(2,4,6-triiso-propyl-phen-yl)sulfon-yl]aziridine in tri-ethyl-amine, diethyl ether and pentane in the presence of moist air. It is formed by a nucleophillic ring-opening that is assumed to be reversible. The mol-ecular structure shows a major disorder of the triiso-propyl-phenyl group over two equally occupied locations. An inter-esting feature is the uncommon hydrate structure, exhibiting a tape-like motif which can be classified as a transition of the one-dimensional T4(2)6(2) motif into the two-dimensional L4(6)5(7)6(8) motif.
Keywords: crystal structure; hydrate; hydrogen bonding; tape-like motif; zwitterion.