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 cations of many metals, but to date, the same crown ether formed both halves of the sandwich. Six new alkalides and an electride have now been synthesized that contain mixed sandwich complexes of alkali metal cations 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- demonstrate the existence of these stoichiometric compounds, but single-crystal X-ray diffraction studies yielded only the crystal systems and cell parameters. 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-were determined, thus verifying the thermodynamic stability of the mixed sandwich compounds relative to the ''parent' compounds that contain only one type of complexant.