Solid State EPR Studies on Bis(1,2-dithiosquarato) cuprates(II): a Structure – Spectroscopy Relationship
Katja Bellin,a Duha Jawad,b Barbara Wenzelc and Peter Strauchb,*
a GKSS-Research Center, Institute of Polymer Research; Kantstr.
55, D-14513 Teltow
b University of Potsdam, Institute of Chemistry, Karl-Liebknecht-Str.
24-25, 14476 Golm;
e-mail: ps@chem.uni-potsdam.de
c Institute of Interdisciplinary Isotope Research e. V. (IIF),
Permoserstraße 15, D-04318 Leipzig
* Corresponding author: E-mail:
ps@chem.uni-potsdam-de
Abstract
1,2-Dithiosquaratometalates (M = Cu, Ni) are available by direct synthesis from
metal salts with dipotassium-1,2-dithiosquarate and the appropriate counter
cations. For EPR measurements in solid state (powder or single crystals) a
diamagnetic dilution of the paramagnetic centers by isostructural host lattices
is necessary to separate the magnetic centers from each other to prevent
interactions. The X-ray structures of two potential diamagnetic hosts (Ph4P)2[Ni(dtsq)2]
1 and [(Ph3P)2N]2[Ni(dtsq)2]
2 as well as the structures of two paramagnetic[Cu(dtsq)2]2–
complexes with sterically demanding counter cations [(Ph3P)2N]2[Cu(dtsq)2]
4 and [p–C6H4(CH2Ph3)2]
[Cu(dtsq)2] 5 are discussed. The copper complexes
4 and 5 as well as (Ph4P)2[Cu(dtsq)2]
3 were studied by solid state EPR spectroscopy as powders or
single crystals and the parameters are compared to those of related complexes in
diamagnetic host lattices. Metal-metal distances of 11–13 Å in the copper
complexes separate the paramagnetic centres sufficiently and reduce the
interactions to enable a well resolved hyperfine structure and to determine the
tensor parameters of the magnetic g- and ACu-tensors.
Keywords: 1,2-dithiosquarate, X-ray, EPR, copper(II), nickel(II)