Influence of the bridging coordination of DMSO on the exchange interaction character in the binuclear copper(II) complex with the nonsymmetrical exchange fragment

Abstract

The binuclear copper(II) complex [Cu2L(CH3COO)] (I), where L3− is the azomethine trianion based on 3-methyl-4-formyl-1-phenylpyrazol-5-one and 1,3-diaminopropan-2-ol, and its DMSO adduct (II) in which the DMSO molecule acts as an additional bridging ligand are synthesized. The structure of complex II is determined by X-ray diffraction analysis, and the structure parameters of the coordination unit of complex I are determined by EXAFS spectroscopy. The μ2-coordination of the DMSO molecule in compound II results in a change in the sign of the exchange interaction parameter. In complex I, the antiferromagnetic exchange interaction (2J = −169 cm−1) occurs between the copper(II) ions. The exchange interaction of the ferromagnetic type (2J = 174 cm−1) is observed in complex II. The quantum-chemical calculations of the magnetic exchange parameters by the density functional theory method show that the role of the DMSO molecule as a switch of the exchange interaction character is exclusively the stabilization of the “broken” conformation of the metallocycles.