CHARACTERIZATION OF COMPLEXES OF LIALH4 W ITH 12-C-4, 15-C-5 AND DICYCLOHEXANO-18-C-6 CROWN-ETHERS - THERMAL-BEHAVIOR OF SOLID-PHASES AND THEIR BENZENE SOLVATES

The thermal behaviour of complexes [Li+-EC](AlH4)(-) with EC = 12-C-4, 15-C-5, DC 18-C-6 (cis-anti-cis and cis-syn-cis isomers) was investig ated by Differential Scanning Calorimetry (DSC). These complexes were prepared as solids from benzene solutions. Pure EC and several solvate d species [Li+-EC](AlH4)(-). nC(6)H(6) (EC = 15-C-5, DC 18-C-6 syn) we re also studied. DSC has revealed various phenomena. Solid-solid trans itions were observed before melting for [Li+-EC](AlH4)(-) with EC = 12 -C-4 and 15-C-5. They are probably explained by small molecular modifi cations strongly dependent on the thermal history of the sample. A gla ss-transition was found for the pure crown-ether DC 18-C-6 anti, the c omplex [Li+-EC](AlH4)(-) with EC = DC-18-C-6 anti and the two solvates mentioned above.