Metal Complexes as Ligands. VI. Antiferromagnetic Interactions in Trinuclear Complexes Containing Similar and Dissimilar Metals

Abstract

The magnetic properties of a series of discrete trinuclear transition-metal complexes derived from tetradentate Schiff bases have been investigated over the temperature range 80°–400°K. The complexes contain the groupings of metals CuMCu where M is Cu(II), Ni(II), Co(II), Fe(II), and Mn(II), and the three metal atoms are linked by oxygen bridges. For each grouping of metals, the observed magnetic moments are subnormal, and decrease markedly with decreasing temperatures. These magnetic properties are explained in terms of antiferromagnetic interactions between the central metal atom M and the adjacent copper (II) atoms. The magnetic moments calculated on the basis of this model of discrete antiferromagnetism are found to be in good agreement with the experimental results. Mutual interactions between the terminal copper atoms apparently exist to only a small degree or not at all.