Carbonyl hydrides reactions

Reduction of the pH of solutions of carbonylate anions yields a variety of protonated species and, from acid solutions, carbonyl hydrides such as the unstable, gaseous H2Fe(CO)4 and the polymeric liquids H2Fe2(CO)g and H2Fe3(CO)n are liberated. The use of ligand-replacement reactions to yield hydrides of higher nuclearity has already been noted. 

The reduction of carbonyl compounds by reaction with hydride reagents (H -) and the Grignard addition by reaction with organomagnesium halides (R - +MgBr) are examples of nucleophilic carbonyl addition reactions. What analogous product do you think might result from reaction of cyanide ion with a ketone ... 

Reaction of Carbonyl Hydrides with Complexes of Group-IB. 

S.3.2.2.2. Reaction of Carbonyl Hydrides with Complexes of Group-IB Metals. 

On irradiation it is converted to the cobalt carbonyl hydride 8, as discussed above. The hydride then reacts with the olefin in a reaction sequence containing only thermal steps /10/. 

Some reactions of carbonyl hydrides will be illustrated in Chapter 22. Such species are involved in catalytic processes in which metal carbonyls function as hydrogenation catalysts. Generally carbonyl hydrides are obtained by acidifying solutions containing the corresponding carbonylate anion or by the reactions of metal carbonyls with hydrogen. The following reactions illustrate these processes ... 

A few metal carbonyl hydrides can be prepared by direct reaction of the metal with CO and H2, with the following being a typical reaction ... 

Several anionic metal carbonyl hydrides stoichiometrically convert acyl chlorides to aldehydes. The anionic vanadium complex [Cp(CO)3VH] reacts quickly with acyl chlorides, converting them to aldehydes [44]. Although no further reduction of the aldehyde to alcohol was observed, the aldehydes reacted further under the reaction conditions in some cases, so a general procedure for isolation of the aldehydes was not developed. 

Molybdenum and tungsten carbonyl hydride complexes were shown (Eqs. (16), (17), (22), (23), (24) see Schemes 7.5 and 7.7) to function as hydride donors in the presence of acids. Tungsten dihydrides are capable of carrying out stoichiometric ionic hydrogenation of aldehydes and ketones (Eq. (28)). These stoichiometric reactions provided evidence that the proton and hydride transfer steps necessary for a catalytic cycle were viable, but closing of the cycle requires that the metal hydride bonds be regenerated from reaction with H2. 

Alkali-immobile dye-releasing quinone compounds, 19 293-294 Alkali lignins, 15 19-20 Alkali manganate(VI) salts, 15 596 Alkali manganates(V), 15 592 Alkali-metal alkoxide catalysts, 10 491 Alkali-metal alkoxides, effects of, 14 252 Alkali-metal alkylstannonates, 24 824 Alkali-metal fluoroxenates, 17 329-330 Alkali-metal hydrides, 13 608 Alkali-metal hydroxides, carbonyl sulfide reaction with, 23 622 Alkali-metal metatungstates, 25 383 Alkali-metal perchlorates, 18 211 Alkali-metal peroxides, 16 393... 

Many of the methods used for the preparation of mononuclear hydrides may be applied to the polynuclear systems. Base attack on metal carbonyls, which furnished one of the first methods for the production of carbonyl hydride species, is applicable to a wide range of carbonyls. Borohydride reduction leads to a variety of products, depending upon the reaction conditions, Os3(CO)12 reacting with NaBH in di-oxane under reflux to give, after 4 hours, a mixture of the anions [H30s4(C0)12] and [H2Os4(CO)i2]2 (79). The related reaction in tetra-hydrofuran for 1 hour yields the anion [HOs3(CO)n]- as the main product with minor amounts of the two tetranuclear anions. 

The interaction of water with the metal carbonyls of osmium and ruthenium has proved to be a very facile route to the metal carbonyl hydrides (86). The corresponding oxygen derivative, H20s3(C0)90, has not been identified in these reactions. There is a wide range of products, summarized in the following chemical equations ... 

Recently proof has been reported for a heterometallic bimolecular formation of aldehyde from a manganese hydride and acylrhodium species [2], Phosphine free, rhodium carbonyl species show the same kinetics as the cobalt system, i.e. the hydrogenolysis of the acyl-metal bond is rate-determining. Addition of hydridomanganese pentacarbonyl led to an increase of the rate of the hydroformylation reaction. The second termination reaction that takes place according to the kinetics under the reaction conditions (10-60 bar, 25 °C) is reaction (3). The direct reaction with H2 takes place as well, but it is slower on a molar basis than the manganese hydride reaction. 

PhSeSiRs reacts with BusSnH under free radical conditions and affords the corresponding silicon hydride (Reaction 1.8) [19,20]. This method of generating RsSi radicals has been successfully applied to hydrosilylation of carbonyl groups, which is generally a sluggish reaction (see Chapter 5). 

Similar to chemical vapor deposition, reactants or precursors for chemical vapor synthesis are volatile metal-organics, carbonyls, hydrides, chlorides, etc. delivered to the hot-wall reactor as a vapor. A typical laboratory reactor consists of a precursor delivery system, a reaction zone, a particle collector, and a pumping system. Modification of the precursor delivery system and the reaction zone allows synthesis of pure oxide, doped oxide, or multi-component nanoparticles. For example, copper nanoparticles can be prepared from copper acetylacetone complexes [70], while europium doped yttiria can be obtained from their organometallic precursors [71]. 

Metal derivatives of cobalt carbonyl hydride such as Tl[Co(CO)4], Zn[Co(CO)4]2, or Cd[Co(CO)4]2 are formed upon reaction of cobalt octacarbonyl with these metals in the presence of carbon monoxide under pressure. Reaction with halogens (X) produces cobalt carbonyl halides, Co(CO)X2. 

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