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Spectroscopic study of dinuclear vanadium cluster encapsulated in sandwich-type heteropolyoxometalate

M. HOSSU1,* , D. RUSU2, M. RUSU3, O. COZAR1, L. DAVID1

Affiliation

  1. “Babes-Bolyai” University, Faculty of Physics, 400084 Cluj-Napoca, Romania
  2. "Iuliu Hatieganu” University, Faculty of Pharmacy, 400026 Cluj-Napoca, Romania
  3. “Babes-Bolyai” University, Faculty of Chemistry, 400028, Cluj –Napoca, Romania

Abstract

The sandwich-type K10[(VO)2Bi2W20O70]⋅24H2O heteropolyoxotungstate was investigated by means of elemental analyses, thermogravimetry and spectroscopic methods (FT-IR, UV−VIS and EPR). The analysis of the coordination mode of the vanadium ions was made by comparing the FT-IR spectrum of the complex those of the K12[Bi2W22O74(OH)2]⋅40H2O ligand. FT-IR spectrum of the complex show the presence of the V=O bonds characterized by νas(V=O) vibrations. In the complex, the coordination of the vanadium shifts the νs(W−Oc,e−W) vibration bands. In UV spectrum, the charge transfer pπ(Oc,e)→dπ*(W) band is shifted in complex compared to the ligand spectrum with ≈ 250 cm−1 towards lower wave numbers. Visible spectrum of the complex contain at 12405 cm−1 and 15905 cm−1 the 2B2(dxy) → 2E(dxz,yz) and 2B2(dxy) → 2B1(dx2 − y2) transition bands for vanadyl ions in C4v local symmetry. The powder EPR spectrum obtained in the X band at room temperature are typical for mononuclear oxovanadium species in an axial environment. The spectrum exhibits eight components both in the perpendicular and in the parallel bands (gII = 1.908, g⊥ = 1.974, AII = 201.6 G, A⊥ = 69.5 G)..

Keywords

Heteropolyoxotungstates, VO complex, FT-IR spectroscopy, UV-VIS spectroscopy, EPR spectroscopy.

Submitted at: Sept. 25, 2007
Accepted at: March 17, 2008

Citation

M. HOSSU, D. RUSU, M. RUSU, O. COZAR, L. DAVID, Spectroscopic study of dinuclear vanadium cluster encapsulated in sandwich-type heteropolyoxometalate, Journal of Optoelectronics and Advanced Materials Vol. 10, Iss. 3, pp. 697-700 (2008)