Self-Assembly of {2}-Metallacryptands and {2}-Metallacryptates

Reaction of H2L (1) with potassium or strontium hydride, or lanthanum(III) chloride, followed by iron(III) chloride, yielded the {2}-ironcryptates 2a–c. The mono-, di-, and trivalent guest cations are endohedrally encapsulated. In contrast, the dinuclear trispyridinium ironcryptand 2d was generated from the reaction of H2L (1) with only iron(III) chloride. The potassium metallacryptate 2a′ was formed from the triple-helicate 2d by addition of potassium carbonate. The new compounds 2b, 2c, and 2d were unequivocally characterised by X-ray diffraction analyses.