COMPLEXATION OF THE CATIONS OF 6 ALKALIDES AND AN ELECTRIDE BY MIXED CROWN-ETHERS

It is well-known that crown ethers form sandwich complexes with the ca tions of many metals, but to date, the same crown ether formed both ha lves of the sandwich. Six new alkalides and an electride have now been synthesized that contain mixed sandwich complexes of alkali metal cat ions with 18-crown-6 (18C6), 15-crown-5 (15C5), and 12-crown-4 (12C4). The properties of Cs+(18C6)(15C5)Na- and Cs+(18C6)(15C5)e- demonstrat e the existence of these stoichiometric compounds, but single-crystal X-ray diffraction studies yielded only the crystal systems and cell pa rameters. The crystal structures of K+(18C6)(12C4)Na-, K+(18C6)(12C4)K -, K+(18C6)(12C4)K-.18C6, Rb+(18C6)(12C4)Na-, and Rb+(18C6)(12C4)Rb-we re determined, thus verifying the thermodynamic stability of the mixed sandwich compounds relative to the ''parent' compounds that contain o nly one type of complexant.