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Larissa R. Cohen Laura A. Pe?a Anton J. Seidl Janet M. Olsen Jennifer Wekselbaum Patrick E. Hoggard 《Monatshefte für Chemie / Chemical Monthly》2009,34(2):1159-1165
Abstract
Near-UV irradiation of solutions of (Bu4N)AuCl4 in aerated ethanol-stabilized chloroform causes the continuous decomposition of chloroform, as evidenced by the production of many equivalents of HCl and peroxides. At the outset of irradiation, most of the AuCl4 − is reduced to AuCl2 −, but the reduction stops and is reversed. The same experiments done in ethanol-free chloroform cause chloroform decomposition only until the irreversible reduction of the gold is complete. In deoxygenated ethanol-free chloroform, irreversible reduction to AuCl2 − is accompanied by the formation of HCl and CCl4, while the main decomposition products in deoxygenated ethanol-stabilized chloroform are HCl and C2Cl6. It is proposed that, in ethanol-free chloroform, photoreduction of AuCl4 − begins with the concerted elimination of HCl from an association complex of CHCl3 with AuCl4 −, and that ethanol suppresses { \textCHCl3 ·\textAuCl4 - } \{ {\text{CHCl}}_{3} \cdot {\text{AuCl}}_{4}^{ - } \} complex formation, leaving a slower radical process to carry out the photoreduction of AuCl4 − in ethanol-stabilized chloroform. In the presence of oxygen, the radical process causes a build-up of CCl3OOH, which reoxidizes AuCl2 − to AuCl4 − and allows the photodecomposition of CHCl3 to continue indefinitely. 相似文献10.
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Summary The reaction between sulphite and gold(III) in hydrochloric acid medium has been studied; an initial complex is formed prior to electron transfer. The reaction rate is inversely proportional to the hydrogen ion concentration and the reaction appears to proceed through the intermediate formation of a free radical which reacts with gold(III) to give the products. Evidence for the formation of dithionate together with sulphate is presented. 相似文献
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The binary complex salt [Co(N2C2H8)3][AuCl4]2Cl has been synthesized. Its crystal structure has been determined. Crystal data for C6H24N6Cl9AuCo: a = 20.8976(14) Å, b = 14.4773(9) Å, c = 7.9944(5) Å; β = 110.809(2)°; V = 2260.9(3) Å3, space group C2/c, Z = 4, d calc = 2.798 g/cm3. The plane square environment of the gold atom of the complex anion is completed to a tetragonal pyramid by the chlorine atom of the neighboring complex anion (Au…Cl 3.538 Å). The structure is layered. Layers of complex cations and complex anions alternate along the X axis. 相似文献
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The oxidation of H2NOH is first-order both in [NH3OH+] and [AuCl4
–]. The rate is increased by the increase in [Cl–] and decreased with increase in [H+]. The stoichiometry ratio, [NH3OH+]/[AuCl4
–], is 1. The mechanism consists of the following reactions.
The rate law deduced from the reactions (i)–(iv) is given by Equation (v) considering that [H+] K
a.
The reaction (iii) is a combination of the following reactions:
The activation parameters for the reactions (ii) and (iii) are consistent with an outer-sphere electron transfer mechanism. 相似文献
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Summary The kinetics of the reaction between nitrous acid and gold(III) in an HCl medium was studied. The reaction was first order with respect to [AuIII] and [HNO2]·H+ and Cl- ions inhibit the rate and alkali metal ions have specific effects on the rate. The reaction appears to involve different gold(III) species, viz. AuCl
inf4
sup–
, AuCl3(OH2) and AuCl3(OH)–, which undergo a two-equivalent reduction to gold(I) leading to the formation of NO
inf2
sup+
which under-goes rapid hydrolysis to give nitric acid. 相似文献
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The kinetics of the reaction between glycolaldehyde (GA) and tetrachloroaurate(III) in acetic acid-sodium acetate buffer has been studied. The reaction is first-order with respect to [AuIII] as well as [GA]. Both H+ and Cl− ions retard the rate of reaction. AuCl4−, AuCl3(OH2), and AuCl3(OH)− are the reactive species of gold(III) with gradually increasing reactivity. A reaction mechanism involving two-electron transfer rate determining steps has been proposed. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 613–619, 1998 相似文献
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The oxidation of hydrazoic acid in perchloric acid in the absence of added chloride under pseudo first-order conditions ([HN3] » [AuCl 4 ? ]) is first order in [Au(III)]. Michaelis–Menten type of dependence (linear plots of k obs ?1 vs [HN3]?1) is observed with respect to [HN3]. The k obs is independent of ionic strength and the plot between k obs ?1 and [H+] is linear. The inner-sphere mechanism is consistent with the formation of an axial complex (K = 25 dm3 mol?1) between AuCl3(HO)? ion and HN3 prior to its rate determining decomposition (k = 0.0182 s?1). It is inferred that the free radicals N 3 ? do not oxidise Au(II). The reaction becomes outer-sphere in the presence of added Cl? ions which are inferred to form a cage around the hydronium ion surrounding the AuCl 4 ? ions. The penetration of N 3 ? through the cage is rate controlling and within the cage, the electron transfer from N 3 ? ion to AuCl 4 ? is fast. The value of the rate determining constant k 2 is 0.547 dm3 mol?1 s?1 and the equilibrium constant K Cl for the cage formation is 5 dm3 mol?1 at 25 °C. It is calculated that the minimum HN3 concentration required before the reaction exhibits zero-order dependence in HN3 is 0.31 mol dm?3 when [H+] = 0.18 mol dm?3 at 25 °C. 相似文献
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PVC matrix and liquid membrane electrodes have been developed for direct potentiometric determination of gold(III). The membranes incorporate nitron tetrachloroaurate(III) as electroactive material. Fast response for gold(III) over the concentration range 10(-5)-0.1M, with response slopes of 52.8-55.2 mV/decade is obtained. The electrodes show good selectivity for gold(III) at pH 2-5 in the presence of many anions and cations. The PVC membrane electrode offers the advantages of greater selectivity (except for Cr(3+), Mn(2+) and ClO(-)(4)) and higher thermal stability. The liquid membrane electrode gives a higher response slope and faster time of response than the PVC membrane electrode. Determination of AuCl(-)(4) over the range 2 mug/ml-2 mg/ml shows an average recovery of 98.5% and a mean standard deviation of 1.0%. Determination of gold in some gold alloys (58.3-99.9% Au) and pharmaceutical preparations gave an average recovery of 99.4% and a mean standard deviation of 0.7%, which are comparable with the performance obtained with the spectrophotometric Malachite Green and gravimetric U.S. Pharmacopeia methods. 相似文献
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《Journal of Inorganic and Nuclear Chemistry》1976,28(8):1545-1547
Rate data for the reduction of AuCl4− by formate, were measured at different temperatures, formate, hydrogen and chloride ion concentrations. AuCl4− and AuCl3(OH)− react with HCOOH and HCOO− in the rate-determining steps of the suggested reaction mechanism to produce AuCl3(HCOO)−. The latter species undergoes a rapid redox reaction in which AuCl2−, Au(o) and CO2 are produced. 相似文献
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Kinetics of the oxidation of arsenious acid by tetrahcloroaurate(III) have been studied spectrophotometrically in hydrochloric acid medium. Initial complex formation between As(III) and Au(III) followed by the decomposition of the intermediate complex to give products of the reaction is suggested. The empirical rate law is k and K are found to be 13.9 × 10?4 s?1 and 24.2 M?1 respectively at 30°C and μ = 1.0 M. ΔH3 and ΔS3 for k are found to be 49.2 kJ mol?1 and - 137.2 JK?1 mol?1 whereas ΔH and ΔS associated with K are - 6.75 kJ mol?1 and 4.14 JK?1 respectively. 相似文献