Heterodinuclear Metal Arrangement in a Flat Macrocycle with Two Chemically- Equivalent Metal Chelating Sites

A phenanthroline-based macrocycle 1 has been newly developed which has two chemically equivalent metal chelating sites within the spatially restricted cavity for dinuclear metal arrangement. The macrocycle 1 reacts with Zn­(CF₃CO₂)₂ or ZnCl₂ to form homodinuclear Zn­(II)-complexes. A single-crystal X-ray structural analysis of the resulting Zn₂1(CF₃CO₂)₄ determined the complex structure in which two Zn­(II) ions are bound by two phenanthroline sites and two CF₃CO₂^– ions bind to each Zn­(II) ion in a tetrahedral geometry. Similarly, a homodinuclear Cu­(I)-macrocycle was formed from 1 and Cu­(CH₃CN)₄BF₄. Notably, from 1 and an equimolar mixture of Cu­(CH₃CN)₄BF₄ and Zn­(CF₃CO₂)₂, a heterodinuclear Cu­(I)–Zn­(II)-macrocycle was exclusively formed in high yield (>90%) because of the relatively low stability of the dinuclear Cu­(I)-macrocycle. A heterodinuclear Ag­(I)–Zn­(II)-macrocycle was similarly formed with fairly high selectivity from a mixture of Ag­(I) and Zn­(II) ions. Such selective heterodinuclear metal arrangement was not observed with other combinations of M-Zn­(II) (M = Li­(I), Mg­(II), Pd­(II), Hg­(II), La­(III), and Tb­(III)).