Speciation of aqueous gold(III) chlorides from ultraviolet/visible absorption and Raman/resonance Raman spectroscopies

Journal Article · Fri Mar 01 04:00:00 EST 1991 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(91)90332-Y· OSTI ID:6078389

Peck, J A; Brown, Jr, G E ^[1]; Tait, C D; Swanson, B I ^[2]

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1. Stanford Univ., CA (United States)
2. Los Alamos National Lab., NM (United States)

Gold(III) speciation in a one molar NaCl aqueous solution at ambient temperature and pressure was determined as a function of pH using ultraviolet/visible (UV/vis) absorption and Raman/resonance Raman (RR) spectroscopies. Gold concentrations in the solutions studies by UV/vis spectroscopy were {approximately}10{sup {minus}4} M whereas those studied by Raman spectroscopy were {approximately}10{sup {minus}2} M. Changes in the intensity and positions of ligand-to-metal charge transfer bands in the UV/vis spectra of the Au(III) chloride solutions with increasing pH are consistent with replacement of chloride by hydroxide ligands. Changes in the number, position, and intensity of Raman and RR spectra of the same solutions are also consistent with successive replacement of chloride by hydroxide ligands in the first coordination sphere of four-coordinated Au(III) with increasing pH. The Raman and UV/vis data are broadly consistent with earlier speciation predictions based on a variety of chemical measurements, but demonstrate that the mixed chloro-hydroxo complexes are more stable than predicted on the basis of theoretically estimated stability constants.

• OSTI ID: 6078389
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Journal Name: Geochimica et Cosmochimica Acta; (United States) Vol. 55:3; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

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ALKALI METAL COMPOUNDS
AQUEOUS SOLUTIONS
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CHLORINE COMPOUNDS
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