Synthesis, crystal structures and magnetic properties of the copper(II) complexes containing isophthalate anion as coligand

Two new dinuclear isophthalato-bridged copper(II) complexes [Cu2(ntb)2(μ-ipt)](ClO4)2·4CH3OH·0.33H2O (1), [Cu2(bbma)2(μ-ipt)(NO3)(CH3OH)]NO3·CH3OH (2) and one mononuclear complex [Cu(bbma)(ipt)(CH3OH)0.67(H2O)0.33]·2CH3OH (3) containing tetradentate and tridentate poly-benzimidazole ligands were synthesized, where ntb is tris(2-benzimidazolylmethyl)amine, bbma is bis(benzimidazol-2-yl-methyl)amine and ipt is isophthalate dianion. All of the complexes were characterized by elemental analysis, IR spectra and X-ray crystallography. The structures of complexes 1 and 2 consist of μ-ipt bridging two Cu(II) centers in a bis(monodentate) bonding fashion. The coordination geometry around the Cu(II) ions of both compounds has a distorted square pyramidal geometry. The Cu···Cu distances are 9.142 and 10.435 Å for 1 and 2, respectively. Complex 3 has a distorted square pyramidal geometry achieved by the three N-atoms of the bbma ligand, one isophthalate-oxygen atom and one oxygen atom from a coordinated methanol molecule. The magnetic susceptibility measurements at variable temperature over the 2–300 K range for complexes 1 and 2 are reported, with J values to be −0.013 and −0.32 cm−1, respectively. The results show that the two complexes exhibit very weak antiferromagnetic interactions between the dinuclear copper(II) centers.