Neutral Ni(II) and Cu(II) complexes of tetraazatetraenemacrocyles

A series of electron donors [neutral NI(II) and Cu(II) complexes of tetraaz atetraenemacrocyclic ligands] differing in metal ion, size of the macrocycl ic ligand, and the length of the aliphatic bridges linking the macrocyclic units in dimeric species were synthesized and their redox, structural and s pectroscopic properties were studied. The x-ray results for the donors unde r study show a nearly planar geometry of the monomeric tetraazamacrocyclic complexes and interesting 'organic-zeolite-like' structures of the dimers. The dimeric Ni complexes have flexible cavities between the two single liga nds linked with aliphatic chains suitable for accommodating some small-size d guests. For the dimeric compounds the metal oxidation [M(II)/M(III)] take s place independently on each centre except one binuclear Ni complex, where the cooperativity of the metal centres was observed. Methyl substituents g ive rise to irreversibility of the oxidation process of the complexes studi ed. In the absence of these substituents neither reorganization nor ligand addition/elimination kinetics affect the electrode process. A common scale for the donors hinder study and some important acceptor compounds (p-benzoq uinone, chloranil, tetracyanoethylene and tetracyanoquinodimethane, etc.) w as proposed on the basis of their cyclic voltammetric behaviour in the same physicochemical conditions. Copyright (C) 2000 John Wiley & Sons, Ltd.