The synthesis of a novel 12-crown-4 analogue (cis-p-dioxano-12-crown-4 or cis-3, 6, 9, 13, 15-pentaoxabicyclo [9.3. 1] pentadecane) is described. The (1: 1) LiNCS complex crystallizes in the monoclinic Cc space group; a= 8.4973 (2) Å, b= 18.0659 (4) Å, c= 8.9168 (1) Å, and β= 90.713 (1)° with Z= 4. The crown adopts C 1 symmetry to which the Li+ is coordinated in a rectangular pyramid with an apical-NCS. Key words: crown ethers, ...