Iron pentacarbonyl-promoted

Recently, the iron-promoted Barbier-type addition of alkyl halides to aromatic aldehydes has been reported (Equation (26)).326 According to the proposed mechanism, the initial step is the formation of an alkyl radical, which can be reduced to the corresponding carbanion. This carbanion nucleophile can react, while coordinated to the iron pentacarbonyl complex, with the corresponding aldehyde. This stoichiometric method is limited with respect to substrate scope and yield. The same authors have also developed the Reformatsky-type addition of cr-halosub-stituted carbonitriles to aldehydes and ketones in the presence of iron pentacarbonyl.3... 

Analogous carbonylation reactions using nickel and iron carbonyl based systems also produce alkanecarboxylic acids [11, 13, 14]. The mechanism of the conversion of benzyl halides into arylacetic acids using iron pentacarbonyl is not as well defined as it is for reactions promoted by nickel or molybdenum carbonyl complexes. Iron... 

As seen from Table III, iron pentacarbonyl reacts satisfactorily in spite of its inertness towards carbon monoxide substitution under the normal conditions 189). In benzene at 80° C, however, Fe(CO)5 dissociates rapidly (190). The Fe(CO)4 generated displays a nucleophilic reactivity which should promote an A-type mechanism. In spite of the specificities discussed, Maitlis et al. 177) have proposed the following mechanism for the metal carbonyl exchange reactions. 

Butanol is prepared commercially by the iron carbonyl-promoted hydro-xymethylation of propylene (Reppe and Vetter, 1953). Iron pentacarbonyl and a tertiary amine serve as a good catalyst system. The active species has been shown to be HFe(CO)4 formed from the metal carbonyl and hydroxide ion (Wada and Matsuda, 1974). 

One of synthetic approaches for the iron nanoparticles is based on the widely used decomposition of iron pentacarbonyl [19, 361, 362], The novelty of the approach is the surfactant system used. Studies with a number of strongly bound surfactants have resulted in decreased magnetic response, due to surface oxidation, disturbing the electronic structure of the surface atoms, or some other mechanism. With this in mind, ones chose to work with a weak surfactant, a p-diketone. P-diketones do have a history as adhesion promoters in bonds between metals and polymers [363], The limited reactivity of p-diketones is as an advantage the P-diketone is much weaker oxidizer than carboxylic acids or alcohols and will not oxidize iron, it is not as nucleophilic as phosphines, yet it is known to be capable of chelating iron. 

In fact, it is not valid to expect an effective flame inhibitor to be also effective for autoignition. Moreover, the same compound can promote the auto-ignition. As an example we can mention iron pentacarbonyl that inhibits atmospheric-pressure H2/air flames but can reduce the ignition delay of the same mixtures. 

Compounds having iron bonded to carbonyl groups as well as to sulfur atoms are numerous, varied, and well studied. The known role of sulfur and selenium as promoters of the high-pressure synthesis of iron pentacarbonyl... 

Corey-Winter elimination dibenzobarralene (442). In a similar way, spirohex-4-ene was obtained in 80% yield from (443). Daub and his co-workers have synthesized several uncommon olefins, among these (442), from parent cyclic thionocarbonates, using iron pentacarbonyl as the efficient elimination promoter. Semmelhack and Stauffer have reported that bis-(cyclo-octa-l,5-diene)nickel (444) converts thionocarbonates of vic-diols into the corresponding olefins in excellent yields and with a high degree of stereospecificity. In connection with a discussion of the mechanistic pathways of this reaction, the authors presented evidence for the intermediacy of the carbene complex (445). 

Pentacarbonyl iron is fairly inert to substitution reactions, and attempts to prepare Fe(CO)5- (CNR) (n = 1-5) by the direct reaction of Fe(CO)5 with isocyanides in Carius tubes has produced only the complexes Fe(CO)s (CNR) (n = 1 and 2). The products were obtained as mixtures that required separation. Other syntheses, including photochemical and trimethylamine N-oxide-promoted displacement of carbonyl groups, or other means, give the same products in variable yield. Procedures based on diiron nonacarbonyl and triiron dodecacarbonyl have produced similar results. The only zero-valent iron complex Fe(CO)5 (CNR) where n > 2 is the complex Fe(CNR)5 prepared either by metal vapor synthesis techniques or by sodium amalgam reduction of iron(II) bromide in the presence of isocyanide. ... 

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