Synthesis and Reactivity of Copper(II) Complexes with New Binucleating Ligands Derived from 16- or 20-Membered N4-Macrocycles

Binuclear C opper(II) Complexes, Synthesis, Catalytic Function New binucleating ligands, (L 1) N ,N ',N",N"'-tetrakis(2-benzimidazolylmethyl)-l,4,9,12-tetraazacyclohexadecane, and (L2) N .N ',N",N"'-tetrakis(2-benzim idazolylm ethyi)-l,4,ll,14-tetraazacycloeicosane were prepared. From the reaction mixture of copper(II) salt and the ligand, new binuclear copper(II) complexes, Cu2(L ') (N 0 3)4 (1), Cu2(L2)(N 0 3)4 (2), Cu2(L_)Br4 (3). and trinuclear complexes, Cu3(L')C16 (4), and Cu3(L2)Cl6 (5) were obtained. Cyclic voltammograms revealed that the trinuclear complexes 4 and 5 are composed with the binuclear complex (1 or 2) and [CuC14]2~. The interaction between two metal ions in the binuclear complexes are confirmed on the basis of the ESR spectra. These binuclear complexes exhibit higher catalytic activity for the oxidation of TMPD by 0 2 molecule than those of structurally rigid binuclear copper(II) complexes and of flexible binuclear complexes in which two copper(II) coordination sites are linked by a single polyatomic chain.