Monoxide metal alkoxides

Carbon monoxide is also known to insert into metal alkoxides (M—OR), di-alkylamides (M—NR2), and some hydroxymethyls (M—CH2OH). For the reaction of the alkoxide (PPh3)2Ir(CO)(OMe) with CO the intermediate [Ir(CO)3(PPh3)2]+ OMe has been identified, and the insertion therefore proceeds via external nucleophilic attack of OMe" on Ir—CO rather than intramolecular OMe migration. True intramolecular transfer is, however, evident for (dppe)PtMe(OMe) where the rate of OMe migration is much faster than for Me migration, to give (dppe)PtMe(COOMe). 

Insertion reactions involving metal alkoxides are also known. For example, carbon dioxide is known to react with some metal alkoxides as shown in equation (12). The formation of a bidentate ligand is a significant thermodynamic driving force for some of these reactions. The isoelectronic aryl and alkyl isocyanates and carbodiimides can react similarly. Insertion reactions involving alkenes and carbon monoxide are known for platinum alkoxides. 

Dimethoxyethane is preferred to dimethyl sulfoxide as solvent for the formyl-ation of ketones with carbon monoxide in the presence of an alkali metal alkoxide. This is due to the fact that DMSO is slightly protic in the presence of a strong base (potassium t-butoxide) and hence not inert. 

Carbon monoxide unites with an alcohol at an elevated temperature and under high pressure, in the presence of a metal alkoxide, to give an alkyl formate. 

Turning now to smaller-volume commodity chemicals, there are already numerous descriptions in the literature to the synthesis of N-substi-tuted formamides, particularly N,N-dialkylformamides, from the corresponding alkylamines plus carbon monoxide (eq. 25). A range of catalysts may be employed, including metallic alkoxides (75), cobalt (76), iron (77), and ruthenium-containing compounds (78), and reaction (25) is the basis of the Leonard process for making N,N-dimethyl-formamide. 

Alkali metal alkoxides catalyse the alcoholysis of esters, by a mechanism analogous to basic hydrolysis. Additionally, alkoxides catalyse the reaction of alcohols with carbon monoxide to give formate esters ... 

In the absence of hydrogen, a catalytic reaction of carbon monoxide and an alcohol produces alkyl formate (Eq. 7.7). The catalyst involved is an alkali metal alkoxide alone or together with a transition metal carbonyl cluster, e.g. Ru3(CO)i2. ° ... 

Two alkoxide derivatives also seem to insert carbon monoxide. The products obtained when these alkoxides are formed in the presence of carbon monoxide have CO inserted between the oxygen and the metal. These two products can also be... 

Here, hydrogen and carbon dioxide react to form water vapor (and carbon monoxide via water-gas shift), which hydrolyzes the aluminum trichloride. If the deposition surface is temperature sensitive, a metal-organic precursor is preferred. Again, an alkoxide is generally used ... 

The C-0 bond can be more easily activated when the CO molecule interacts with more than two metal atoms. Recently, the dissociative adsorption of carbon monoxide by polynuclear metal complexes, such as [(silox)2TaH2]2 (Eq. 57) [126, 127] and [(silox)2WCl]2 (Eq. 58) [126-129], and tetratungsten alkoxides [129] has been achieved. Hydrogenation of CO to give hydrocarbons promoted by metal clusters has been reviewed [130]. 

Thus the hard oxygen bases react more readily with metal carbonyls than the softer bases. Alkoxide ions attack coordinated carbon monoxide to form alkoxy carbonyl complexes. This reaction (Eq. 2-75) has been observed for many complexes of the metals Mn, Re, Ee, Ru, Os, Co, Rh, Ir, Pd, Pt, and Hg. 

To determine the number of electrons around the transition metal in a complex the valence electrons from the metal ion are added to those contributed by all the ligands. The numbers of electrons donated by various classes of ligands are summarized in the table. Anions such as halides, cyanide, alkoxide, hydride, and alkyl donate two electrons, as do neutral ligands with a lone pair such as phosphines, amines, ethers, sulfides, carbon monoxide, nitriles, and... 

Insertion of carbon monoxide followed by reductive coupling is an old reaction that continues to be studied and developed. Examples of this reaction are the carbonylation of nickel dialkyl complexes to give ketones, " alkyl-alkoxides to yield esters, and alkyl-amides to give organic amides (Equation (79)). The carbonylation of the binuclear complex 145 leads to the formation of an isoquinolone ring with the elimination of one of the two Ni atoms, but no GO insertion occurs at the second metal moiety. Hydrolytic cleavage of the remaining Ni-G bond provides the free heterocyclic base (Scheme 45). ... 

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