Synthesis and magnetostructural characterization of dinuclear copper(II) complexes with the diazine ligand, 3,6-bis(di-2-pyridylmethyl)pyridazine

Abstract

The crystal structures of [Cu₂(bdpdz)Br₄]·2CH₃CN 1, [Cu₂(bdpdz)Cl₃(H₂O)]Cl·3.5H₂O 2 and [Cu₂(bdpdz)₂][ClO₄]₄3 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.