182Tungsten Mössbauer spectroscopy of heteropolytungstates

Abstract

The tungsten-182 Mössbauer spectra of a series of Keggin structure heteropolytungstates, [EW₁₂O₄₀]ⁿ⁻ are reported. There is a very considerable variation in quadrupole coupling at the tungsten nucleus indicating considerable asymmetry in the electron distribution for the more electronegative elements E. The quadrupole coupling correlates well with the structural data, in particular with the distance between the tungsten and the oxygen atom of the EO₄group. These compounds may be regarded as rigid W₁₂O₃₆ cages interacting more or less strongly with an EO₄ⁿ⁻host. The spectra of salts of metatungstate [H₂W₁₂O₄₀]⁶⁻ and [W₆O₁₉]²⁻ are also given.