MAGNETIC EXCHANGE INTERACTIONS IN BINUCLEAR TRANSITION-METAL COMPLEXES .20. VARIATION IN MAGNETIC EXCHANGE INTERACTION FOR A SERIES OF METAL(II) COMPLEXES OF A BINUCLEATING LIGAND

Variable-temperature magnetic susceptibility data, measured down to 4.2 K, are reported for Cu (II), Ni (II), Co (II), Fe (II), and Mn (II) complexes of the binucleating ligand formed from the condensation of 2 mol of 2,6-diformyl-4-methylphenol with 2 mol of 1,3-diaminopropane. A strong antiferromagnetic exchange is present in the binuclear Cu (II) complex and is characterized by J=-294 cm-1, where the spin Hamiltonian is taken as H=-2JŜI-Ŝ2 for all the complexes. The net antiferromagnetic interaction decreases monotonically in the series Cu (II), Ni(II) (J=-27 cm-1), Co (II) (J=-9.3 cm-1), and Fe(II) (J=-4.2 cm-1) and finally becomes a net ferromagnetic exchange interaction with the Mn(II) complex where j=+0.2 cm-1. The variation in J value across the series is attributed to (1) the changing number of unpaired electrons and associated exchange pathways and (2) the increasing metal-ligand plane distance in going from Cu (II) to Mn(II). © 1979, American Chemical Society. All rights reserved.