Ni2+ coordination in aqueous NiCl2 solutions: Study of the extended x-ray absorption fine structure

Extended x-ray absorption fine structure measurements are reported for aqueous NiCl2 solutions of molar concentration 2.78 and 3.74. Analysis of the Fourier filtered spectra by a multiparameter fitting procedure reveals a first coordination sphere consisting of six water molecules with an Ni–O bond distance of 2.07 Å, and no first sphere Ni–Cl coordination. Measurement of an outer coordination sphere consisting of both Cl− ions and water molecules is also reported. The relationship of these results to previously postulated ordered structures in these solutions is discussed.