Laboratory EXAFS determined structure of the stable complexes in the ternary Ni(ii)–EDTA–CN− system

Abstract

Aqueous solutions of the ternary system Ni(II)–EDTA–CN⁻ are investigated with X-ray Absorption Spectroscopy (XAS) as a function of cyanide concentration with an enhanced laboratory von Hámos X-ray spectrometer. The near-edge structure of the spectra identifies unambiguously the formation of the pentacyanidonickel(II) complex at excess CN⁻ concentrations. An analysis of the extended energy range of the XAS spectra reveals the molecular structure of the distinct molecular components present and provides a detailed description of the barely detectable mixed ligand [NiEDTA(CN)]³⁻ complex. This thorough Extended X-ray Absorption Fine Structure (EXAFS) study demonstrates the potential of the emerging laboratory XAS spectrometers to become routine probes in various areas of chemistry, materials science, physics and related disciplines.