COMPLEXATION OF METAL-CATIONS BY THE CRYPTAND 1,1'-(1,4,10-TRIOXA-7,13-DIAZACYCLOPENTADECANE-7,13-DIYLDICARBONYL)FERROCENE

Multinuclear NMR spectroscopy has been employed to study the configuration adopted in solution by the 3-fold nonsymmetrically bridged ferrocene-containing cryptand 1,1'-(1,4,10-trioxa-7,13-diazacyclopentadecane-7,13-diyldicarbonyl)ferrocene when complexed with the range of metal cations Be2+, Mg2+, Ca2+, Sr2+, and Ba2+. The results show unambiguously that formation of complexes of 1:1 stoichiometry involves coordination of the cations with a cis configuration of the amide carbonyl groups. This results in the creation of a plane of symmetry in the complex, which is not present in the host. The guest cations are selectively coordinated on the short side of the host macrocycle.