Magneto–structural correlation of dimeric copper(II) carboxylates with pyridyl-substituted nitronyl nitroxides
摘要:
The synthesis, crystal structure and magneto-structural correlations of three new paddle-wheel type dicopper(II) carboxylate complexes with pyridyl-substituted nitronyl nitroxides, [Cu-2(mu-Me3CCO2)(4)(NITpPy)(2)](C6H6) (1), [Cu-2(mu-CH3CO2)(4)(NITpPy)(2)] (2), and [Cu-2(mu-C6H6CH2CO2)(4)(NITmPy)(2)] (3) (NITpPy = 4,4,5,5-tetramethyl-2-(4-pyridyl)-2-imidazoline-N-1-oxyl N-3-oxide, NITmPy = 4,4,5, 5-tetramethyl-2-(3-pyridyl)-2-imidazoline-N-1-oxyl N-3-oxide) are reported. Structures of complexes 1-3 consist of a symmetrical dimeric Cu(II) carboxylate paddle-wheel core and pyridyl nitrogen atoms of radical ligands at the apical position. Cryomagnetic susceptibilities were measured in the temperature range 4-300 K. According to the structural results, the magnetic data are discussed in terms of four S = 1/2 spin units involving one strong coupled dicopper(II) unit plus two monomer nitroxyl radicals. It is found that two paddle-wheel copper(II) ions are strongly coupled antiferromagnetically with J = - 192, - 172, and - 160 cm(-1) for complexes 1, 2, and 3, respectively, while the interactions between copper(II) and the radicals are very weak. The magneto-structural correlations for complexes 1, 2, and 3 are discussed on the basis of the structural parameters and magnetic data for the complexes (C) 1999 Elsevier Science S.A. All rights reserved.
Influence of ligands’ peripheral substituents on the structure, magnetochemical and electrochemical behaviour of complexes containing a Cu2O2 butterfly core
作者:Nataliya E. Borisova、Marina D. Reshetova、Tatiana V. Magdesieva、Victor N. Khrustalev、Grigori G. Aleksandrov、Maxim Kuznetsov、Roman S. Skazov、Alexandr V. Dolganov、Vladimir N. Ikorskiy、Vladimir M. Novotortsev、Igor L. Eremenko、Iliya I. Moiseev、Yuri A. Ustynyuk
DOI:10.1016/j.ica.2007.10.020
日期:2008.5
New polydentate open structure ligands H(3)L1 and H(3)L2 were synthesized by the condensation of 2,6-diformyl-4-tert-butylphenol and corresponding N-R-o-phenylenediamines (R = Ac and R = Boc). Treating of the ligands with copper trimethylacetate leads to binuclear copper complexes with dissimilar Cu(2)O(2) cores, the structures of which were solved by X-ray diffraction analysis. The electrochemical properties of both complexes were studied; the observed redox transitions were assigned to specific redox-active sites of the molecule. These assignments were confirmed by DFT calculations of the electronic structure of binuclear complexes. Both complexes exhibit anti-ferromagnetic behaviour, as confirmed by variable-temperature magnetic studies. (C) 2007 Elsevier B.V. All rights reserved.