STRUCTURES OF ISOMERIC SUBSTITUTED 14-CROWN-4 ETHERS AND THEIR LISCN COMPLEXES

Crystal structures of methyleno,tetracyclopentyl-14-crown-4 (1), methyl,tetracyclopentyl-14-crown-4 (2), methyleno,didecalino-14-crown-4 (3), methyl,didecalino-14-crown-4 (4), 2.LiSCN and 4.LiSCN were determined by X-ray diffraction methods. The free ligands, 2 and 4, have their rings collapsed, but on complexation open up to accommodate an Li+ ion. It is bonded to all four O atoms of the crown in each case and to an apical SCN- ion to form a rectangular pyramid. The methyl group is pseudoaxial in 2.LiSCN and pseudoequatorial in 4.LiSCN. In 2 and 4 the bridging propylene groups are disordered over two sites.