Structure of a Gold(III) Hydroxide and Determination of Its Solubility
Journal
Bulletin of the Chemical Society of Japan
Journal Volume
89
Journal Issue
11
Start Page
1385
End Page
1390
ISSN
0009-2673
1348-0634
Date Issued
2016-11
Author(s)
Kawamoto, Daisuke
Ando, Hiroaki
Ohashi, Hironori
Kobayashi, Yasuhiro
Honma, Tetsuo
Ishida, Tamao
Tokunaga, Makoto
Okaue, Yoshihiro
Yokoyama, Takushi
Abstract
A representative gold(III) complex ion ([AuCl4]), successively hydrolyzes to form [AuCl4n(OH)n] (n = 04) in aqueous solution as the pH increases and, finally, precipitates. It has been referred to as gold(III) hydroxide for the past fifty years. However, whether the precipitate is gold(III) hydroxide (Au(OH)3) or hydrous gold(III) oxide (Au2O3nH2O) has remained uncertain. Few studies have been conducted to determine its chemical and physical properties. The aim of this investigation is to identify the precipitate and to determine its solubility. The precipitate was X-ray amorphous. Based on the transmission electron microscopy (TEM) observation, the shape was spherical and the particle diameter was approximately 9 nm. From the results of 197Au Mössbauer spectroscopy, Au L3-edge X-ray absorption (XA) spectroscopy and thermogravimetry/ differential thermal analysis (TG/DTA) measurements, the precipitate composition was estimated to be Au(OH)3. Based on the composition, its structure was proposed to be a linear polymer. Moreover, its solubility at 298K was determined to be 0.00120 g/100 g of H2O. This chemical and physical properties information of Au(OH)3 is essential for gold chemistry, for example, for preparing supported gold catalyst.
Subjects
Differential thermal analysis
Gold
High resolution transmission electron microscopy
Physical properties
Precipitates
Precipitation (chemical)
Solubility
Solutions
Thermoanalysis
Transmission electron microscopy
Chemical and physical properties
Complex ions
Gold chemistry
Linear polymers
Particle diameters
Ssbauer spectroscopies
Supported gold catalysts
X-ray amorphous
Gold compounds
Publisher
Oxford University Press (OUP)
Type
journal article