Anionic Gold Research Articles

Selective ion flotation of gold

A conceptually simple model for the continuous ion flotation process was developed and tested experimentally. The experimental system consisted of an aqueous solution of gold and silver cyanide anions and the surfactant collector, cotyltrimethylammonium bromide. The surfactant was shown to be highly selective for the gold over the silver. Very good agreement between the predicted and the experimental gold and silver recoveries was obtained for a wide range of experimental gas and feed fluxes. The results indicated a unique relationship between recovery and the value of the volumetric feed to gas rate ratio.

A facile, novel way to prepare anionic, neutral and cationic gold(I) complexes

The complex ppn[Au(acac)2]1 can be obtained by reacting ppn[AuCl2] with [TI(acac)] in 1:2 molar ratio, and complex 1 reacts with compounds of the type RH in which H has some acidic character to give the corresponding [AuR2]– species; RH = CH2(CN)22, CH2(CO2Me)23, CH2(CN)CO2Me 4, Me3SiCCH 5, 2-SH-C5H4N 6, AuR RH = CH2(PPh2)2, 7, or [AuR2]+ RH =[(4-MeC6H4)3PCH2C5H4N-2]ClO48.

Optical Properties of Anionic Gold Centers in CsBr and CsI Crystals

AbstractOptical studies are for the first time performed on Au− centers in Cs‐halides. Absorption spectra above 90 K and emission and excitation spectra down to 13.9 K are investigated for CsBr:Au− and CsI:Au− crystals. In both the crystals four absorption bands exist called D1, C, B, and A and two emission bands called B′ and A′ in the order of decreasing energy. In CsBr, a luminescence resembling α emission known in other alkali systems is also observed, but it seems not to be peculiar to Au− centers because of its dependence on the thermal treatment of the specimens. The King‐Van Vleck factors, λ, which are obtained by analyzing the optical data are 2.5 (CsBr) and 2.2 (CsI), which are larger than unity as in the case of all other alkali halides: Au− so far investigated.

Gold Anions in Alkali Bromide Melts: Solubility and Optical Spectrum

Gold Anions in Alkali Bromide Melts: Solubility and Optical Spectrum

Studies of the Chemical Properties of Size Selected Metal Clusters: Kinetics and Saturation

ABSTRACTOur studies of small (n=2−40) gas phase transition metal clusters (cations, neutrals and anions) have revealed a number of size-dependent chemical and physical properties. This paper will discuss results involving activated dissociative molecular chemisorption of hydrogen (deuterium) and small alkanes on cationic, neutral and anionic platinum and gold clusters. For example, we have yet to find any size gold cluster anion to exhibit measurable reactivity towards di-deuterium, but reactivity is observed on small (n<15) gold cations and very small (n<9) neutral gold clusters. Methane or ethane chemisorption occurs most readily only on small Pt and Au cluster cations and least rapidly, if at all, on cluster anions. The larger Pt and Au clusters are found to be non-reactive towards the alkanes under our experimental conditions.At the other extreme, at steady state, small clusters of Pt, Rh, Ni, Pd, V, Nb, and Ta are hydrogen “rich” exhibiting H/M stoichiometrics >> 1. These results are consistent with a limited data base on supported clsutes obtained via EXAFS measurements and have important implications for catalytic reactions involving hydrogen and light hydrocarbons.

The X-ray crystal structure and physical properties of (BEDT-TTF) AuBr 2Cl 2

The X-ray crystal structure and electrical conductivity properties of a 1:1 BEDT-TTF salt containing (AuBr 2Cl 2) - are reported. The unit cell consists of square-planar gold (III) anions segregated by stacks of BEDT-TTF + cations with a repeat pattern of 4.467(2) Å along the crystallographic a axis. Four-probe variable-temperature conductivity measurements indicate that this material is a semiconductor with an activation energy of 0.13 eV. ESR measurements carried out on an oriented single-crystal specimen show a monotonic decrease in linewidth from 19 to 2.1 G over the temperature range 300-100 K.

The use of colloidal metal particles in protein blotting

AbstractTwo procedures are described for staining the overall protein pattern on transfer membranes. Both methods involve the use of colloidal metal particles. AuroDye staining is based on the interaction of anionic colloidal gold particles with cationic proteins at low pH. The method is highly sensitive, but limited to nitrocellulose and polyvinylidene difluoride membranes. FerriDye comprises an incubation in a cationic iron (hydrous) oxide sol and subsequent intensification with potassium hexacyanoferrate in acidic medium. FerriDye is of intermediate sensitivity, but there are no limitations concerning membranes. It can be used on nitrocellulose‐, nylon‐and polyvinylidene difluoride‐based membranes. An immunodetection procedure is described which uses colloidal gold‐labelled secondary antibodies to visualize antigen‐antibody interactions. This signal can be significantly enhanced by silver. The procedure explained uses a new light‐insensitive and user‐friendly silver enhancement system.

Evidence for the gold anion in ethylenediamine

On prouve par des methodes electrochimiques et spectroscopiques l'existence de Au − dans l'ethylene-diamine par une reaction Au s +e − →Au −

Ortho-, meta- and para-nitrophenylgold(I) complexes

Treatment of [BzPh3P][AuCl2] with [Hg(x-C6H4NO2)2] (x = o, m, or p) gives anionic gold(I) complexes of the type [BzPh3P][Au(R)Cl](R = o-, m- or p-C6H4NO2, Bz = C6H5CH2). The chloro ligand in [Au(o-C6H4NO2)Cl]− can be replaced by bromo or iodo ligands by use of NaBr or NaI. The anions [Au(R)Cl]− react with neutral monodentate ligands, L, to give neutral mononuclear complexes [Au(R)L] (R = o-C6H4NO2, L = PPh3, AsPh3; R = m-C6H4NO2, L = PPh3) and with 1,2-bis(diphenylphosphino)ethane (dpe) to give [Au2(R)2(dpe)] (R = o-C6H4NO2). The corresponding [Au(p-C6H4NO2)Cl]− reacts with PPh3 or AsPh3 to give mixtures containing [AuClL]. The anionic ortho-nitrophenylgold(I) complex is much more stable than its meta- or para-nitrophenyl isomers. These are thought to be the first reports of nitrophenylgold(I) complexes.

A new way of synthesising diarylgold(III) complexes using organomercury compounds

Treatment of [Me 4N][AuCl 4] with di-organomercury derivatives R 2Hg in which R is an ortho-nitroaryl group (R = o-O 2NC 6H 4 or 2-CH 3, 6-O 2NC 6H 3) gives anionic gold(III) complexes of the type cis-Me 4N[AuR 2Cl 2]. These react with (a) KCN, to give the anionic complexes cis-Me 4N[AuR 2(CN) 2], (b) neutral monodentate ligands (L) to give the neutral complexes cis-[AuR 2Cl(L)] (L = PPh 3, PCy 3, py), and (c) 1,2-bis(diphenylphosphino)ethane (dpe) in the presence of NaClO 4 to give the cationic complexes cis-[AuR 2(dpe)]ClO 4. The complexes are thought to be the first transition metal complexes containing ortho-nitroaryl ligands.

Anionic gold

In recent years, research into the formation and properties of metallic anions in solution has led to interesting advances in our knowledge of alkali metal and gold anions. The latter may have possible uses in the separation of gold from base metals and in refining applications.

Direct Atomic Absorption Spectrophotometric Analysis of Anion Complexes of Platinum and Gold After their Concentration and Separation from Aqueous Solutions by Anion Exchange Chromatography

Abstract A strongly basic anion exchange chromatography column (Dowex 2X-8) is utilized for the concentration and separation of platinum and gold anion complexes from aqueous solutions at pH 6. Atomic absorption spectrophotometry has shown to be a very sensitive and selective detection system for the determination of the metallic species. When the column effluent is fed directly to the nebulizer of the atomic absorption instrument detection limits, using a 10-ml sample, are 0.4 μg for Pt and 0.03 μg for Au. These detection limits can be proportionately improved by passing larger sample volumes through the column. A linear relationship between signal and concentration is readily achieved using the procedure.

Novel anionic gold(I) and gold(III) organocomplexes

Summary Tetrahydrothiophen (tht) and/or chloride may readily be displaced from ClAu(tht) with perhaloaryl lithium to give anionic complexes of the [R 2 Au] − or [RAuX] − type (R = C 6 F 5 or C 6 Cl 5 ; X = Cl or Br). Anionic gold(III) complexes can be prepared both by the reaction of Cl 3 Au-(tht) or K[AuCl 4 ] with LiC 6 F 5 or by the oxidative addition of halogens or (C 6 F 5 ) 2 TlBr to gold(I) complexes.