INTERACTION OF SODIUM AND POTASSIUM-IONS WITH THE CIS ISOMERS OF DICYCLOHEXYL-18-CROWN-6 IN NONAQUEOUS MEDIA

The formation constants, K-s, for 1:1 complexes of the cis-syn-cis and cis-anti-cis isomers of dicyclohexyl-18-crown-6 with sodium and potas sium cations have been electrochemically determined in 10 nonaqueous ( protic and aprotic) media. Linear correlations were obtained for log K -s with standard Gibbs transfer energies of the cation from water to a given solvent. The cis-anti-cis isomer was found to be a weaker compl exer than the cis-sm-cis one and this was elucidated in terms of the l igand solvation. Energy-minimized structures of the ligands and comple xes surrounded by methanol and acetonitrile molecules were established by molecular dynamics computations.