Jump to main content
Jump to site search

Issue 34, 2010
Previous Article Next Article

Series behavior of lanthanoid(III) complexes with the α-1-Wells-Dawson heteropolyoxoanion in acetonitrile: electrochemistry and Ln coordination

Author affiliations

Abstract

The tetra-n-butylammonium (TBA+) salts for a series of lanthanoid(III) (Ln = Nd, Sm, Eu, Tb, Dy, Yb, and Y) complexes with the α-1-isomer of the Wells-Dawson heteropolyoxoanion, α-1-[P2W17O61]10−, were prepared and characterized by voltammetry, controlled-potential bulk electrolysis, Eu L3-edge XANES spectroelectrochemistry, and Ln L3-edge X-ray absorption spectroscopy. Aspects of the series behavior across the 4f period for the complex anions with nominal 1 : 1 Ln(III):α-1-[P2W17O61]10− stoichiometries are detailed. The voltammetric response of the α-1 ligand alone in dry acetonitrile (with 0.1 M (TBA)PF6 electrolyte) is concentration independent and remarkably well-defined with five waves attributable to W-based redox processes. The formation of heteropoly blue solutions upon electrochemical reduction results in chemical instabilities and isomerization. The deliberate addition of water turns an otherwise ideal response into a broad and poorly resolved one, wherein the first reduction process is shifted 150 mV to more positive electrode potentials. Upon its coordination with Ln(III) ions, the voltammetric response develops notable complexities with as many as ten concentration-dependent couples attributable to W-based redox processes of the Ln:α-1 complexes. The results from in situ Eu L3-edge XANES of the Eu(III):α-1 complex provide no evidence for the one-electron reduction of Eu(III) at controlled electrode potentials comparable to those that were previously found to form Eu(II) in the potassium salt of the corresponding Eu(III) complex upon reduction in an aqueous electrolyte. To explain the contrasting system behaviors, the Ln(III) coordination environments in the TBA5H2[(H2O)nLn(α-1-P2W17O61)] solid salts, including the extent of Ln hydration (n) upon their dissolution in acetonitrile, were determined through use of EXAFS, which demonstrates a structural uniformity among the salts and their acetonitrile solutions, wherein the average Ln-O interatomic distances and O coordination numbers reveal variations that are consistent with the effects of the lanthanoid contraction. The side-by-side comparison of the solid and solution data provides evidence that is consistent with a partial solvent (H2O–CH3CN) exchange upon dissolution in MeCN. Details of the Ln(III) coordination chemistry, wherein the decrease in the ionic radius from the large, light Nd(III) to the small, heavy Yb(III), are presented in the context of known structural and physical phenomena of acetonitrile solvates, aqua ions, and the corresponding water-soluble K7[(H2O)4Eu(α-1-P2W17O61)] complex.

Graphical abstract: Series behavior of lanthanoid(iii) complexes with the α-1-Wells-Dawson heteropolyoxoanion in acetonitrile: electrochemistry and Ln coordination

Back to tab navigation

Supplementary files

Publication details

The article was received on 29 Apr 2010, accepted on 03 Jun 2010 and first published on 30 Jul 2010


Article type: Paper
DOI: 10.1039/C0DT00394H
Citation: Dalton Trans., 2010,39, 7980-7992

  •   Request permissions

    Series behavior of lanthanoid(III) complexes with the α-1-Wells-Dawson heteropolyoxoanion in acetonitrile: electrochemistry and Ln coordination

    M. R. Antonio, J. Jing, B. P. Burton-Pye and L. C. Francesconi, Dalton Trans., 2010, 39, 7980
    DOI: 10.1039/C0DT00394H

Search articles by author

Spotlight

Advertisements