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)).