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An experiment has been conducted to study the chemistry and the variable-temperature magnetic properties of macrocylic copper and nickel complexes. Three spin interaction methods have been used to describe the magnetic properties of the tetranuclear complexes. The anti-ferromagnetic interaction of the Ni-O(phenoxo)-Ni bridge angle was reflected using the magneto-structural correlation of phenoxo-bridged nickel(II) complex.

Dinuclear copper complexes containing tridentate dinucleating ligands are prepared and considered as structural and functional models for catechol oxidases. In these complexes, the Cu(II) centers undergo antiferromagnetic coupling. The crystal structure of the complexes remain unchanged in the methanolic solution. The copper complex of 1,5-bis(2-benzimidazolyl)-3-pentanol exhibits catecholase activity by oxidizing 3,5-di-tert-butylcatechol to quinone.

The synthesis and characterization of a series of heterobimetallic complexes Fe(III)M(II)L(mu-OAc)(OAc)(H2O)(ClO4).nH20 and Fe(III)Co(III)L(mu-OAc)(OAc)2(mu-O)(ClO4)2.3H2O are described. The scheme uses the dihydroxy-bridged diiron(III) complex FeIII(HL)2(mu-OH)2(ClO4)2 derived from a tetraaminodiphenol macrocyclic ligand as the precursor. The exchange coupling constants for these complexes were obtained.

Two series of dicopper(II) complexes derived from bis( N- salicylidine)dicarboxylic acid dihydrazides (H 4 L n ) of general formula [Cu 2 (L n )· x H 2 O]· y H 2 O and [Cu 2 (H 2 L n )Cl 2 · x H 2 O]· y H 2 O have been synthesized and characterized, where n refers to the number of carbon atoms in the aliphatic spacer between the two N- salicylideneacylhydrazine units. Magnetic susceptibility measurements for neutral dicopper(II) complexes [Cu 2 (L n )· x H 2 O]· y H 2 O indicate significant antiferromagnetic coupling between copper(II) centers. The -2 J values obtained from the Bleany-Bowers equation are within the range 121-223 cm -1 , suggesting association of the coordinated copper(II) units Cu(ONO) via phenoxy bridges. This leads to a polynuclear structure in which the dimeric units are connected with the aliphatic spacer. From the best-fit values of the mole fraction of paramagnetic uncoupled copper(II) centers ( ρ ), the degree of association in these polynuclear copper(II) complexes has been estimated. The chloro dicopper(II) complexes [Cu 2 (H 2 L n )Cl 2 · x H 2 O]· y H 2 O with n = 0, 2 and 3 also show strong antiferromagnetic exchange coupling (-2 J = 215-423 cm -1 ), suggesting a polynuclear structure in which the copper(II) is in a distorted square-pyramidal environment, bound in the equatorial plane with a monoanionic ONO tridentate acylhydrazone unit and the μ-phenoxy oxygen and the axial site occupied by a chloride. The dicopper(II) complexes with n = 1 and 4 show weak antiferromagnetic exchange coupling (-2 J = 16-20 cm -1 ). In these complexes the chloride ion may occupy the fourth equatorial site while the μ-phenoxy is in the apical position. [ABSTRACT FROM AUTHOR]