Osmium coordinatively unsaturated, reactions with

Reduction of alkyl osmium complex 160 with NaBH4 or NaBD4 gives the methyl hydrido and methyl deutero osmium complexes 169. Treatment of 169 with trityl cation gives the metallaheterocycle 170. This reaction probably occurs via cationic intermediates 171 and 172. The coordinatively unsaturated 172 then undergoes an intramolecular oxidative addition with... 

It is particularly hazardous to the eyes because of its ready reaction with organic matter, a property exploited in electron microscopy in order to stain and fix biological tissues. Although osmium is a d8 transition metal, its tetroxide is a coordinatively unsaturated 16-electron species and has a tetrahedral structure3. It is highly soluble in carbon tetrachloride (375 g/ 100 g), less so in benzene, and moderately soluble in water (7.24 g/100 g). 

Photochemical Activation. Coordinative unsaturated fragments may also be produced by photolytic reactions. In presence of UV-irradiation metal carbonyl compounds lose sequentially CO-ligands. Electron-deficient, solvent coordinated species produced in this way may combine with inactivated metal complexes via the formation of donor-acceptor metal-metal bonds. Iron, ruthenium, and osmium trinuclear carbonyl clusters may be prepared by this way ... 

The first mixed-metal cluster of Os-Pd, [Os6Pd(bipy)(CO)i8], was reported in 1994, and since then a variety of mixed-metal cluster that contain various Os Pd ratios have been created. Palladium-pyridine complexes appear to be useful reagents in the synthesis of mixed-metal clusters with osmium carbonyl compounds. " The reaction of the coordinately unsaturated cluster [Os3(yu-H)2(CO)io] with [Pd(NH3)2l2] afforded a number of Os-Pd clusters with a high hydride content. " Both palladium phosphine and bidentate phosphine complexes are useful in the preparation of high-nuclearity mixed-metal clusters. The reaction of [Os3(/i-H)2(CO)io] with [Pd2(/i-dppm)2Cl2] gave 258 and 259, in addition to 260, with the same metal core, " in which the molecule contains a twofold symmetry axis. " " ... 

As many carbonate complexes are synthesized usually in aqueous solution under fairly alkaline conditions, the possibility of contamination by hydroxy species is often a problem. To circumvent this, the use of bicarbonate ion (via saturation of sodium carbonate solution with COj) rather than the carbonate ion can often avoid the precipitation of these contaminants. Many other synthetic methods use carbon dioxide as their starting point. Transition metal hydroxo complexes are, in general, capable of reacting with CO2 to produce the corresponding carbonate complex. The rate of CO2 uptake, which depends upon the nucleophilicity of the OH entity, proceeds by a mechanism that can be regarded as hydroxide addition across the unsaturated C02. There are few non-aqueous routes to carbonate complexes but one reaction (3), illustrative of a synthetic pathway of great potential, is that used to prepare platinum and copper complexes. Ruthenium and osmium carbonate complexes result from the oxidation of coordinated carbon monoxide by dioxygen insertion (4). ... 

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