Silver oxygen bonding

In phosphine and arsine complexes of the type LM(diketonate) (M = Ag, Au) and CuL2(dike-tonate), t]2 oxygen bonded diketonate ligands occur in the copper(I) and silver(I) derivatives but the gold(I) analogues feature the jj, carbon bonded form.483... 

The gas phase oxidation of ethylene to ethylene oxide over silver catalysts has been studied extensively.49 la-c It has been suggested that epoxide formation involves transfer of oxygen from a silver-oxygen complex to the olefin on the catalyst surface.4913 Silver-on-silica also catalyzes the liquid phase oxidation of cumene to cumene hydroperoxide. A mechanism that involved insertion of coordinated oxygen into a C—H bond was proposed630 ... 

Figure 4 Selectivity in epoxidation for a range of substrates plotted against the dissociation enthalpy of the weakest C-H bond in the olefin (m) TS-1 peroxide system (u) silver-oxygen system. 1. 1-octene, 2. 1-butane, 3. 2-butane, 4. gropene, 5. 4-unyltoluene, 6. 1-3 butadiene, 7. styrene, 8. 4-vinylpyridine, 9. ethylene.2...

Discussion Point DP2 Silver is unique among metal catalysts for its high selectivity in the epoxidation of ethylene. Rationalize this result on the basis of the different properties of surface metal-oxygen bonds and of the different adsorption behaviour of hydrocarbons on transition and non-transition metals. 

In AgNCO the isocyanate groups are linked by Ag atoms which form two collinear bonds (Ag-N, 2-12 A). (The silver-oxygen distances, 3-00 A, are too long for normal bonds compare 2-05 A in AgiO.)... 

The second question regarding the extended interaction is whether it can be responsible for a site-specific interaction In principle, the answer is yes, because the LUMO consists of lobes of a lateral size whieh is eomparable to the characteristic length scale of the atomie eorrugation potential. Indeed, in our DFT analysis [33] we find that the aeeumulated eharge between moleeule and metal (the bond ) does not have the same lateral distribution of the LUMO but exhibits contributions of the LUMO andihe silver surfaee [33]. There is no reason why such a structured bond should not be site speeifie. We ean thus conclude that it is not necessarily the local oxygen bonds alone whieh are responsible for site specificity. 

As this review is intended to illustrate, the interplay between metal and oxygen leads to a richness of reactivity that is reflected in the surface structure of oxides. Much of this richness can be rationalised as varying proportions of ionic and covalent character in the metal-oxygen bonding, and is manifest in a variety of non-stoichiometric surfeces. We therefore focus on the prototypical transition metal oxide smface rutile Ti(>2 (1 1 0). This is contrasted with computational results for one of the most widely-studied p-block oxide surfaces - corundum Al2O3-(0 0 0 1) - and we refer also to computational surface studies on oxides of ruthenium, iron, vanadium, tin and silver, as well as ternary oxides. 

Oxygen bonds on the typical metal catalysts, namely platinum and silver, are of different strength, and two forms—molecular and atomio— coexist on the surface. 

Figure 3. The percent of total oxygen bonded to silver as a function of silver coverage for several oxygen-containing polymers and oxygen-plasma-roocfified PS.

Verify that a solid solution containing one part cuprous iodide and three parts silver iodide has an average metal-iodine bond length equal to the oxygen-oxygen bond length of ice. 

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