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Spectroscopic and magnetic studies of new vanadyl tungstophosfate and tungstoarsenate with an open well- Dawson structures

D. RUSU1, A. MARCU2, O. BABAN3, M. RUSU3, M. HOSSU2, L. DAVID3,*

Affiliation

  1. “Iuliu Hatieganu” University Faculty of Pharmacy, 400032 Cluj-Napoca, Romania
  2. ”Babes-Bolyai” University, Faculty of Physics, 400084 Cluj-Napoca, Romania
  3. “Babes-Bolyai” University, Faculty of Chemistry, 400028, Cluj Napoca, Romania

Abstract

The K9[{VO(H2O)4}{VO(H2O){K(H2O)2}(P2W18O66)] (1) and K9[{VO(H2O)4}{VO(H2O){K(H2O)2}(As2W18O66)] (2) complexes were prepared and investigated through spectroscopic (FT-IR, UV-VIS, ESR) methods and magnetic susceptibility measurements. The analysis of the coordination mode of the vanadium ions was made by comparing the FTIR spectra of the complexes (1) and (2) with those of the K11[{K(H2O)3}2{K(H2O)2}(P2W18O66) and K11[{K(H2O)3}2{K(H2O)2}(As2W18O66) ligands. The shift of as(W-Oe-W) and as(W-Oc-W) vibrations bands shows the coordination of each vanadyl ion at oxygen atoms from the belt region.The UV electronic spectra of the complexes and of the ligand contain one bands characteristic for the ligand to metal charge transfer in the heteropolyanion cage. The visible electronic spectra of both complexes in aqueous solution are tipicaly for vanadyl ions in C4v environment. Powder EPR spectra obtained in the X band contains two Gaussian components, one axial and another isotropic, in the 2:3 ratio. The simulation of the experimental spectra indicate the trapping of the unpaired electrons at the parent VIV paramagnetic ions and the absence of direct delocalization towards the neighboring vanadium ions. The very broad component observed in the EPR spectra are proofs for the existence in both samples of dipolar coupled vanadium(IV) ions..

Keywords

Clusters, FTIR, UV-VIS, EPR Spectroscopy.

Submitted at: Nov. 15, 2006
Accepted at: March 15, 2007

Citation

D. RUSU, A. MARCU, O. BABAN, M. RUSU, M. HOSSU, L. DAVID, Spectroscopic and magnetic studies of new vanadyl tungstophosfate and tungstoarsenate with an open well- Dawson structures, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 3, pp. 577-582 (2007)