A N,N′-diacetate benzodioxotetraazamacrocycle and its transition metal complexes

The 2,9-dioxo-1,4,7,10-tetraazabicyclo[1.10.1]hexadeca-1(11),13,15-triene-4,7-diacetic acid (H2L1) reacts with CuCl2 · 2H2O leading to the benzodioxochlorocomplex [Cu(L′1)Cl] (1). The stability constants of H2L1 with Cu2+, Ni2+, Zn2+, Cd2+ and Pb2+ were determined, and the values follow the trend [Ni(H−1L1)]− > [Cu(H−1L1)]− ≫ [Pb(H−1L1)]− > [Zn(H−1L1)]− > [Cd(H−1L1)]−. The effect of pH on the coordination sphere of the Cu complexes was also studied by spectroscopic measurements.