Macrocyclic ligand design: structure-function relationships involving the interaction of cobalt(II), nickel(II) and copper(II) with mixed donor macrocyclic ligands

摘要

A comparative investigation of the interaction of Co(II), Ni(II) and Cu(II) with a series of mixed-donor dibenzo-substituted macrocyclic ligands, incorporating O2N3-, O2N4-, O3N2-, O3N3- and O4N2-donor sets, has been carried out. The thermodynamic stabilities of the respective complexes in 95% methanol (I = 0.1; Et4NClO4, 25 degrees C) have been determined. All ligands form 1.1 (metal:ligand) species with the above metal ions although, in a few instances, species of type MLH2+ were also detected. In an attempt to elucidate ligand structure/function relationships, an analysis of the effect of variation of ligand backbone and/or donor atom set on the respective complex stabilities has been carried out; the results are compared with those obtained previously for related mixed-donor (cyclic) systems. The x-ray structure of the nickel(II) nitrate complex of the O3N3-donor macrocycle (V) is presented. C23H35N5NiO10 crystallised in the monoclinic space group P2(1), with a = 17.201(3), b = 11.341(2), c = 11.742(3) Angstrom, beta = 104.34(2)degrees and Z = 4. (C) 1998 Elsevier Science S.A. All rights reserved. [References: 40]