1,5,9-Trioxacyclododecane and 3,3,7,7,11,11-hexamethyl-1,5,9-trioxacyclododecane: novel lithium cation complexing agents

Abstract

12-Crown-3 and its hexamethyl derivative, obtained in good yield from oxetane and from 3,3-dimethyloxetane, give stronger complexation than the corresponding 16-crown-4 ligands, and the high selectivity for lithium as compared with sodium and magnesium is retained for Me₆-12-crown-3, but is lost for 12-crown-3 owing to the formation of sandwich complexes; X-ray crystal structures are reported for 12-crown-3·LiNCS, Me₆-12-crown-3·LiClO₄, and Me₆-12-crown-3.