μ2-Oxalato-bridged tricopper(II) complex derived from 1,4,8,12-tetraazacyclopentadecane: Synthesis, structure and magnetic characterization

A novel tricopper bridged oxalato complex with the structural formula [Cu(tacp)(H2O)]2[Cu(μ2-C2O4)2(ClO4)2] (1) where tacp = 1,4,8,12-tetraazacyclopentadecane was synthesized. The complex was characterized by X-ray crystallography and by spectroscopic techniques (IR and visible). The magnetic properties were also measured at variable temperatures (300–2 K). In this compound each oxalate is acting as a bridging ligand between two Cu2+ ions, where two types of coordination modes are found for the oxalate: monodentate and bidentate fashions. The magnetic coupling between the Cu–Cu centers is very weak antiferromagnetic (the singlet–triplet energy coupling J = −0.9 cm−1) and is in full agreement with the structural results.