| Summary: | The syntheses of samarium, holmium, and ytterbium complexes of a tris-amide calix[4]arene are described, and the resulting structures are compared with the previously reported gadolinium complex. The syntheses involved the reaction of 5,11,17,23-tetra-tert-butyl-24-hydroxy-26,27,28- tris(diethylcarbamoylmethoxy)calix[4]arene with the appropriate lanthanide picrate hydrate. Structural studies demonstrated that a picrate anion acts as a quasi-bidentate ligand with Sm (and Gd), is unidentate in the Ho complex, but is found in the second coordination sphere for the smallest lanthanide cation (Yb) investigated.
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