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Dinuclear Copper(II) Complexes Containing Oxamate and Blocking Ligands: Crystal Structure, Magnetic Properties and DFT Calculations

Abstract

Three dinuclear copper(II) complexes containing oxamate-based ligands with the chemical formula [Cu(opba)Cu(dap)(H2O)]•H2O (1), [Cu(opba)Cu(dap-OH)(H2O)]•1.5H2O (2) and [Cu(opba)Cu(en)(H2O)]•4H2O (3) in which opba = o-phenylenebis(oxamato), dap = 1,3-diaminopropane, dap-OH = 2-hydroxy-1,3-diaminopropane and en = ethylenediamine have been synthesized and their crystal structures have been determined by single-crystal X-ray diffraction. The molecular structures of 1-3 consist of neutral dicopper(II) complexes obtained by the "complex as ligand" strategy, in which each [Cu(opba]2‒ fragment acts as a bidentate ligand towards the copper(II) ion bonded to the amine capping ligands (dap, dap-OH and en) and the two other carbonyl groups are uncoordinated. Variable-temperature magnetic susceptibility measurements of 1-3 in the temperature range of 4-300 K reveal a strong antiferromagnetic coupling between the metal centers through the oxamate bridge with J = −183.5 cm−1 (1); J = −195.8cm−1 (2), and J = −195.6 cm−1 (3). The fit of the variable-temperature magnetic susceptibility data of 3 revealed that coupling CuIICuII•••CuIICuII between the dinuclear entities is very weak. In all cases, the Hamiltonian used was H = −JS1•S2. DFT calculations based on the broken-symmetry formalism were used to provide further insight and an explanation for the reported behavior.

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Article information


Submitted
07 Nov 2019
Accepted
13 Jan 2020
First published
13 Jan 2020

New J. Chem., 2020, Accepted Manuscript
Article type
Paper

Dinuclear Copper(II) Complexes Containing Oxamate and Blocking Ligands: Crystal Structure, Magnetic Properties and DFT Calculations

T. R. G. Simões, W. D. do Pim, K. C. Metz, M. A. Ribeiro, D. Valente, T. M. Cardozo, C. B. Pinheiro, E. F. Pedroso, B. A. C. Horta, C. L. M. Pereira, G. P. Souza and H. O. Stumpf, New J. Chem., 2020, Accepted Manuscript , DOI: 10.1039/C9NJ05584C

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