EPR Study of Gadolinium(III) Complexes with Heteropolyanions: [Gd(SiW11O39)2]13- and [GdP5W30O110]12-

A. Szyczewskia, S. Lisb, Z. Kruczyńskia, J. Pietrzaka, S.Butb, and M. Elbanowskib aDepartment of Solid State Spectroscopy, Institute of Physics, Adam Mickiewicz University, Umultowska 85, 60-614 Poznań, Poland bDepartment of Rare Earths, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznań, Poland

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The gadolinium complexes: [Gd(SiW11O39)2]13- [I] and [GdP5W30O110]12- (Gd-encrypted Preyssler anion) [II] have been chosen for EPR study. This study is a continuation of our recent investigation related to solid gadolinium complexes: β-diketonates and aminopolycarboxylates. The EPR spectra of the Gd-polyoxometalates studied provide much better resolution than those recently studied. The spectra of Gd-polyoxometalates containing 1.7 to 2.5% of Gd(III) do not require an additional computer processing for correct interpretation. It is on the contrary to the β-diketonates and polyaminocarboxylates (with the content of Gd(III) 22-33%) for which the use of the RKU computer program (based on Fourier transform) was necessary in order to enhance the spectra resolution thus improving their correct interpretation. The EPR spectra obtained for the compounds I and II markedly differ from the U-spectrum characteristic of Gd(III) in glasses. Taking into account the spin-Hamiltonian calculations the existence of Gd(III) ion in two different surroundings: in a strong crystal field of rhombic symmetry and in a weak crystal field, is observed. The differences observed between the case I and II seem to be related to a various hydration degree.

DOI: 10.12693/APhysPolA.90.345 PACS numbers: 76.30.Kg