Tellurium and nickel homobinuclear metallamacrocycles based on the redox-active dioxolene ligands

Abstract

Ditopic ligand containing two 3,6-di-tert-butyl-o-benzoquinonato fragments linked through 4-position by resorcinol bridge was utilized for synthesis of metallamacrocyclic complexes with tellurium and nickel. Both compounds consist of two metal-centered coordination units connected by two bis-dioxolenes. Coordination units have distorted octahedral geometry. Four coordinated oxygen atoms of dioxolenes form uncompleted distorted octahedron environment. The lacking sites in octahedron coordination sphere are filled with electronic lone pairs in the case of tellurium and phenanthroline ligand in the case of nickel. In contrast to previously described cobalt and nickel complexes with the same bis-dioxolene, metal units are situated not cofacially. The reason of this is saturation of coordination sphere of central atom until octahedron which excludes coordination with internal solvent molecule which can connect both metals.