SYNTHESIS AND MAGNETOSTRUCTURAL CHARACTERIZATION OF DINUCLEAR COPPER(II) COMPLEXES WITH THE DIAZINE LIGAND, 3,6-BIS(DI-2-PYRIDYLMETHYL)PYRIDAZINE

The crystal structures of [Cu2(bdpdz)Br4].2CH3CN 1, [Cu2(bdpdz)Cl3(H2O)]Cl.3.5H2O 2 and [Cu2(bdpdz)2][ClO4]4 3 were determined by X-ray analysis, where bdpdz represents the binucleating ligand 3,6-bis(di-2-pyridylmethyl)pyridazine, formed by the reaction of 3,6-dichloropyridazine and di-2-pyridylmethyllithium. Compounds 1 and 2 consist of discrete binuclear units, in which copper atoms are linked by the diazine bridge and two halide ions. The pyridazine acts as a hexadentate ligand. In complex 2 the two copper(II) ions have a distorted octahedral co-ordination geometry, 4 + 2. Compound 3 also consists of discrete binuclear units, in which the copper centres are linked by two organic ligands. Here bdpdz acts as a pentadentate ligand, with one of the diazine nitrogen atoms not bonded. The two copper(II) ions have a square pyramidal co-ordination geometry, 4 + 1. The magnetic susceptibility was investigated in the temperature range 300-5 K. These measurements reveal an antiferromagnetic interaction for all three compounds (-2J = 98.1 for 1, 79.6 for 2 and 6.4 cm-1 for 3). The lack of a diazine bridge, N-N, for the perchlorate salt 3 substantially reduces the antiferromagnetic interaction.