Gold carbonyl cations

The gold analog, [AujCOjj] is reported to be formed (with an [Sb2Fu] counterion) only under 100 bar CO [107]. The y(CO) bands of these species occur significantly above the stretching frequency of free CO (2143 cm ) for example the silver and gold tricarbonyl cations have IR absorptions at 2192 and 2212 cm respectively. This is taken to indicate that there is little or no metal —> CO Ti-backdonation in these species, which are termed non-classical metal carbonyls [109]. 

H. Willner, and F. Aubke, Reaction of Carbon Monoxide in the Superacid HS03F-Au (S03F)3 and the Gold(I) Bis(carbonyl) Cation [Au(CO)2]+. Isolation and Characterization of Gold(I) Carbonyl Fluorosulfate, Au(CO)S03F, Inorg. Chem. 29, 2195-2200 (1990). 

Fielicke A, von Helden G, Meijer G, Pederson D, Simard B, Rayner D (2005) Gold cluster carbonyls Saturated adsorption of CO on gold cluster cations, vibrational spectroscopy, and implications for their structures. J Am Chem Soc 127 8416... 

On the descriptive side, previously known binary carbonyl cations are usually of the [M(C0)6] type with M = Mn, Tc or Re (82), The oxidation state of the metal in these or other ternary cations is 0 or +1, and the ionic charge of the complex does not exceed +1. In addition, far more basic anions are used as counter ions. The effective atomic number rule, which plays an important role in judging stability, structure and reactivity of transition-metal carbonyls, is not valid for the noble-metal carbonyl compounds reported so far. The silver(I) and gold(I) carbonyl derivatives have 14, and the Pt(II) carbonyls have 16 electrons in the metal valence shell. 

Gold(I) complexes of the type [AuCl(PPh3)ra] (n= 1, 2) or [Au(N03)(PPh3)] show an excellent performance towards oxidative addition carbonylation or aromatic amines to form corresponding carbamates, and also towards the carbonilation of aliphatic amines to produce either alkylureas or formamides.2552,2553 Cationic gold(I) compounds of the type [AuL]+ where L = phosphine, phosphite, or arsine are excellent catalysts for the addition of alcohols to alkynes.2554... 

DF calculations were carried out on CO complexes of small neutral, cationic, and anionic gold clusters Au with n= 1-6. The -coordination mode (terminal C-coordination) was found to be the most favorable one irrespective of the charge of the cluster, and cluster planarity is more stable for the bare clusters and their carbonyls. As expected, adsorption energies are greatest for the cationic clusters, and decrease with size. Instead, the adsorption energies of... 

Solutions containing the [Au(GO)]+ cation are also obtained by treatment of commercial gold(m) oxide AU2O3 with concentrated sulfuric acid in a CO atmosphere. Depending on the reaction conditions, both [Au(CO)]+ and [Au(CO)2]+ are present in these solutions as demonstrated by IR and NMR spectroscopy. The solution catalyzes the carbonylation of terminal olefins and a mechanism has been proposed for the process (Equation (55)). This... 

Salts with the [Au(CO)2]+ cation have been proposed to be important intermediates in the transport of gold in hydrothermal fluids. Gold deposits may accumulate through formation and decomposition of (carbonyl)gold salts under geochemically relevant conditions, similar to the mechanism advanced with salts based on the [Au(SH)2]- anion.303... 

Klingler and co workers—impact of metal coordination on the formate pathway. Klingler and coworkers114,125 carried out studies on the cation reactivity of formate in solution at 180 °C, 7.8 mol/L of H20 with the solvent triethylene glycol, and the formate concentration was varied. It was noted that formic acid produced from the carbonylation of water is catalyzed by hydroxide anion, and rapidly builds up to close to equilibrium concentration levels under these conditions, so that they had to use gold plated stainless steel autoclaves. They obtained a first order dependency of the water-gas shift reaction rate (i.e., H2 evolution rate) with formate concentration. As a control experiment, they added metal pentacarbonyl iron to the reactor, and observed no additional rate increase, indicating that the water-gas shift... 

Mono- and di-carbonyls have been formed at the surface of a gold field-emitter tip at room temperature in the presence of an electric field 60 they could be field-desorbed to give gaseous cations carrying one or two charges. The driving force for these reactions was thought to be the local positive... 

The acyl cation (acylium ion, oxocarbonium ion) is a resonance hybrid of the two main contributing structures 192 and 192a. The importance of structure 192a is indicated, for instance, by the high frequency carbonyl absorption (2200-2300 cm-1) observed in acyl cations generated from acyl halides and Lewis acids (Olah et al., 1962, 1963 Bethell and Gold, 1967). 

The nucleophilic addition of alcohols to alkynes was reported by Utimoto with NaAuCU and later by Teles with cationic gold complexes.The enol ethers formed can be hydrolyzed to form carbonyl compounds or trapped as ketals (equations 4 and 5). An intramolecular version of this reaction was reported by the group of Genet to give bicyclic ketals (equation On the basis of this concept, a glycosidation... 

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