Res. Chem. Intermed.
, Vol. 33, No. 8–9, pp. 901–914 (2007)
Also available online - www.brill.nl/rci
EPR studies of spin–spin interactions between Cu(II)
centers in dimeric, hexameric and homo- and
heteronuclear tetrameric complexes
, VLADIMIR KOKOZAY
Faculty of Chemistry, University of Wroclaw, 14 Joliot-Curie Str., 50-383 Wroclaw, Poland
Department of Inorganic Chemistry, National Taras Shevchenko University,
Volodimirska str. 64, Kyiv 01033, Ukraine
National High Magnetic Field Laboratory FSU,
1800 E. Paul Dirac Drive, Tallahassee, FL 32310-3706, USA
Received 12 May 2006; accepted 5 June 2006
Abstract—Applications of conventional (X-band), High-Field and High-Frequency EPR to study the
nature of exchange interactions between Cu(II) centres in different homo- and hetronuclear systems
are reviewed. The ﬁne structure EPR spectra have been observed and analyzed in terms of spin-
Hamiltonian parameters corresponding to S 1 for different [Cu
complexes present in one unit cell, Cu(II) dimers possessing different conformations, dimeric species
formed between Cu(II) ions and polyfunctional ligand in solution, Cu–Zn–Cu–Zn and Cu–Co–Cu–Co
tetrameric heterometallomacrocycles, Cu
cubane-like tetramers and for the chain Cu(II) hexamer.
Keywords: EPR; HF EPR; copper; zinc; cobalt; dimer; tetramer; hexamer; heteronuclear; complex;
high spin; exchange interactions.
EPR spectroscopy is a much more sensitive technique for investigation of spin–
spin interactions smaller than 1 cm
as compared to the measurements of static
magnetic susceptibility. The interactions weaker even by three orders of magnitude
) still lead to a characteristic EPR spectrum, distinctly different
from the spectrum of the individual paramagnetic centers.
The splitting of the S = 1 levels in zero magnetic ﬁeld (ZFS) measured by
parameter D is demonstrated schematically in Fig. 1 for the simplest case of two
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