COMPLEXES WITH DIIMINE LIGANDS - SYNTHESES AND MAGNETIC-BEHAVIOR OF DINUCLEAR COMPLEXES OF COPPER(II), NICKEL(II) AND COBALT(II) WITH 2,5-BIS(2-PYRIDYL)PYRAZINE

The synthesis, characterization and voltammetric and magnetic behaviour of a series of dinuclear complexes mu-(2,5-DPP)[M(hfacac)2]2, in which hfacac is hexafluoroacetylacetonate, 2,5-DPP is 2,5-bis(2-pyridyl)pyrazine and M = copper(II), nickel(II) and cobalt(II), are described. As with the dinuclear complexes derived from 2,3-bis(2-pyridyl)pyrazine (2,3-DPP) and analogous ligands, magnetic measurements show that these systems are not coupled. On the basis of magnetic data, we propose that, in contrast to related ligands such as 2,2'-bipyridyl, the coordinated 2,5-DPP cannot be planar.