Extended X-ray absorption fine structure study of polynuclear cationic selenium clusters

Abstract

Homopolynuclear selenium cations have been structurally characterised in solution, for the first time, using X-ray absorption spectroscopy. In H₂SO₄· 30% SO₃ oleum and in NaCl–AlCl₃ eutectic at 150 °C, oxidation of selenium produces, respectively, two- and three-species equilibria between dipositively charged selenium ions of different nuclearities. Their structural determination was performed by reference to the X-ray absorption spectra of solid Se₄(AlCl₄)₂ and Se₈(AlCl₄)₂.