MACROCYCLIC LIGAND DESIGN - STRUCTURE-FUNCTION-RELATIONSHIPS INVOLVING THE INTERACTION OF COBALT(II), NICKEL(II) AND COPPER(II) WITH MIXED-DONOR MACROCYCLIC LIGANDS

A comparative investigation of the interaction of Co(II), Ni(II) and C u(II) with a series of mixed-donor dibenzo-substituted macrocyclic lig ands, incorporating O2N3-, O2N4-, O3N2-, O3N3- and O4N2-donor sets, ha s been carried out. The thermodynamic stabilities of the respective co mplexes in 95% methanol (I = 0.1; Et4NClO4, 25 degrees C) have been de termined. All ligands form 1.1 (metal:ligand) species with the above m etal ions although, in a few instances, species of type MLH2+ were als o detected. In an attempt to elucidate ligand structure/function relat ionships, an analysis of the effect of variation of ligand backbone an d/or donor atom set on the respective complex stabilities has been car ried out; the results are compared with those obtained previously for related mixed-donor (cyclic) systems. The x-ray structure of the nicke l(II) nitrate complex of the O3N3-donor macrocycle (V) is presented. C 23H35N5NiO10 crystallised in the monoclinic space group P2(1)/n, 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.