Spectrophotometric investigations of the reaction between gold(III) and potassium iodide

Abstract

The equilibria of the complex formation between AuCl4-n(OH)n - and I- was studied spectrophotometrically in aqueous solutions containing KI:Au(III)?2 in the acidity range from 1 M HCl to pH 7 at 25?C. From the hydrogen ion and Cl-ion dependence of the absorption spectra, it was found that AuCl2I2 - and Au(OH)2I2 - complexes were formed. The equilibrium constants of complex formation were determined.

Electrospray ionization mass spectra of the reactions of NaAuBr4and related aurates with nucleophiles

“…Electrospray ionization mass spectra in the negative ion mode, ESI(À)MS, of aqueous solutions of AuBr 3 at different pH values have been reported by us, [1] confirming the rapid equilibria (speciation) that were observed by spectrophotometry: [2][3][4] AuBr 4…”

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Electrospray ionization mass spectra of the reactions of NaAuBr 4 and related aurates with nucleophilesAdditional supporting information may be found in the online version of this article at the publisher's web site.

Dear Sir,Electrospray ionization mass spectra in the negative ion mode, ESI(À)MS, of aqueous solutions of AuBr 3 at different pH values have been reported by us, [1] confirming the rapid equilibria (speciation) that were observed by spectrophotometry: [2][3][4] AuBr 4

…”

“…[5] Thus, gold seems to be unique among all the elements of the periodic table, not only because of the properties of the metal, known from the beginning of the mankind, and of the gold nanoparticles, [6,7] but also because gold(III) salts do not precipitate easily Au(OH) 3 under neutralization, particularly in the presence of anions such as bromide or cyanide. [8,9] With the aim of uncovering further features of aurate(III) ions, we carried out a series of MS experiments that are reported for the first time: (1) the characterization of commercially available samples of NaAuBr 4 and NaAuCl 4 at different pH values, (2) the detection by ESI(À)MS of the exchanges of ligands (Cl/Br/CN) in aurates and (c) a study of the reactivity (or lack of reactivity) of NaAuBr 4 with alcohols, phenols, carbonyl compounds, 1,3-dicarbonyl or 1,3dicarboxyl compounds, and oximes, also followed by ESI(À)MS.…”

“…Moreover, aurates with several bromo/bromido ligands are more stable than their analogous Cl complexes, and cyano/cyanido-aurates even more (in fact, we could not replace cyano ligands by hydroxide ions, or any other ligands). Some of these reactions were studied spectrophotometrically years ago, with results [2][3][4] that ESI(À)MS has now confirmed. We also show that ESI(À)MS is a quick technique to gain further insight into these exchanges.…”