Alternate Arrangements of Two Different Metals at Chemically-Equivalent Binding Sites on a Circle

Two different metal ions, monovalent M+ (M = Ag, Cu) and divalent Hg2+, were alternately arranged on a circle with a diameter of 1.5 nm in such a way that six metal ions were put between two disk-shaped hexamonodentate template ligands (L), thereby forming the sandwich-shaped hexanuclear complexes [M3Hg3L2](9+). In spite of the fact that all six binding sites are completely equivalent, the arrangement of the two kinds of monovalent and divalent metal ions is precisely controlled to minimize electrostatic interactions between the adjacent metal ions.