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Spectroscopic investigation of trinuclear metallic cluster encapsulated in silico 9- wolframic heteropolyanion

M. HOSSU1, A. ILIE2, D. RUSU3, O. COZAR1, M. RUSU2, L. DAVID1,*

Affiliation

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

Abstract

The polyoxometalate [M3 n+(H2O)6(SiW9O34)2](20-3n)-, M = Fe (III) (1), Co (II) (2), Ni (II) (3) was preparated and investigated by thermal analysis, FTIR, UV-Vis and ESR spectroscopies in order to determine the coordination of metallic ions, the local symmetry around them and the spin state. The co-ordination mode of transition metal ions was made by means comparison between the FTIR spectra of the sandwich-type complexes with those of α-A-Na10[SiW9O34]·24H2O ligand. The relatively small shift of the νas(W=Ot) vibration band is due to the fact the terminal Ot atoms are not involved in the metal ions coordination. The opposite shift of νas(W-Oe-W) and νas(W-Oc-W) frequencies for the bonding from the belt region shows the co-ordination of each metallic ion at oxygen atoms from corner-sharing octahedral. The UV electronic spectra of the sandwich-type complex and of the ligand contain two bands characteristic for the ligand to metal change transfer in the heteropolyoxometalates frame. Information about the local environment of Fe (III), Co (II) and Ni (II) ions have been obtained by means of d-d transitions from the visible electronic spectrum performed in aqueous solution. Powder ESR data show the presence of small antiferromagnetic interactions in the spin frustrated trinuclear metallic clusters..

Keywords

Trinuclear metallic cluster, FTIR, ESR.

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

Citation

M. HOSSU, A. ILIE, D. RUSU, O. COZAR, M. RUSU, L. DAVID, Spectroscopic investigation of trinuclear metallic cluster encapsulated in silico 9- wolframic heteropolyanion, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 3, pp. 711-715 (2007)