Iron hydrocarbonyl

Iron pentacarbonyl Iron nonacarbonyl Iron dodecacarbonyl Iron hydrocarbonyl... 

The nonacarbonyl is an orange-yeUow crystalline solid at ambient temperatures density 2.85 g/cm decomposes at 100°C. Iron dodecacarbonyl is a black crystalline solid density 2.0g/cm3 decomposes at 140°C. Iron hydrocarbonyl is an unstable colorless liquid solidifies at -70°C decomposes on heating insoluble in water, soluble in alkalis. 

Reaction with an alkah produces iron hydrocarbonyl ... 

Iron hydrocarbonyl reacts with halogens forming halogen substituted carbonyl derivatives ... 

Also, iron hydrocarbonyl can combine with several metals forming metallic derivatives in which hydrogen is replaced by the metal ions ... 

Reppe and Vetter 17) have shown that the aqueous solutions prepared by treating iron pentacarbonyl with alkali react with olefins at elevated temperature to form the next higher alcohols. This reaction was thought to be due to the presence of iron hydrocarbonyl, H2Fe(CO)4, and formulated according to Equation (10) ... 

Since the catalyst used in the hydroxymethylation reaction is obtained by treating iron pentacarbonyl with aqueous alkah, it will be necessary to consider first the reactions that occur when iron pentacarbonyl is treated with this reagent. Krumholz and Stettiner (18) have shown that when one mole of iron pentacarbonyl is treated with three moles of sodium hydroxide in aqueous solution, iron hydrocarbonyl anion, [HFe(CO)4] is formed according to Equation (12) ... 

Iron hydrocarbonyl has been repeatedly reported to be an active hydro-formylation catalyst [165, 166]. Some papers state that it is active at a lower pressure than cobalt [23, 165, 166, 168-170]. However, in a recent paper it was shown that iron hydrocarbonyl is only 1 10 times as active as Co carbonyl [824, 980]. Other authors recommend adding iron carbonyl as a promoter to Co catalysts [171, 979]. 

A reaction closely related to olefin hydroformylation is the Reppe alcohol synthesis [239, 1003]. It is carried out in alkaline media with Fe(CO)5 catalyst and differs from the Roelen reaction in that water is used instead of hydrogen, with the result that alcohols are obtained directly at lower temperatures. The active catalyst is believed to be a salt of the iron hydrocarbonyl. 

Iron hydrocarbonyl Hydrogen tetracarbonylferrate(ll) C4H2Fe04 12002-28-7 169.902 col liq unstab -70 dec s alk... 

Olefin isomerization has been widely studied, mainly because it is a convenient tool for unravelling basic mechanisms involved in the interaction of olefins with metal atoms (10). The reaction is catalyzed by cobalt hydrocarbonyl, iron pentacarbonyl, rhodium chloride, palladium chloride, the platinum-tin complex, and by several phosphine complexes a review of this field has recently been published (12). Two types of mechanism have been visualized for this reaction. The first involves the preformation of a metal-hydrogen bond into which the olefin (probably already coordinated) inserts itself with the formation of a (j-bonded alkyl radical. On abstraction of a hydrogen atom from a diflFerent carbon atom, an isomerized olefin results. 

The conditions for the synthesis must differ, as the electronic configuration of each metal changes, but the intermediate in each case probably is a complex in which acetylene and carbon monoxide are each linked to two metal atoms. Cobalt and iron compounds having both acetylene and carbonyl bridges have already been synthesized 27). The report of the preparation of a dimeric nickel hydrocarbonyl, [NiH(CO)a]2 by Behrens 28) may well lead to the isolation of a siipilar acetylene complex with nickel. 

Active catalysts are nickel, cobalt, iron, rhodium, ruthenium and palladium, as well as their salts, carbonyls or hydrocarbonyls. 

Besides nickel and cobalt, almost all of the catalysts discussed in the last chapter which were suited for the formation of free acids can be applied, e. g. rhodium, palladium and, with certain restrictions, iron. Cobalt hydrocarbonyl catalyzes the stoichiometric ester synthesis at mild reaction conditions [35, 121]. The initially formed acylcobalt carbonyls react rapidly with alcohols even at 50 °C and, in the presence of Na-alcoholate, even at 0 °C to give esters [121]. Dienes with isolated double bonds react with carbon monoxide and alcohols at mild reaction conditions in the presence of Pd/HCl to give unsaturated monocarboxylic acid esters and at more severe conditions to give saturated dicarboxylic acid esters [508]. 

The following facts support the assumption that the true catalysts are the transition metal hydrocarbonyls rather than the corresponding metal carbonyls. Only metals which can form hydrocarbonyls, like cobalt, rhodium and iron, can act as catalysts [123, 280, 673, 674], whereas nickel, e.g., is inactive [123, 673] in most cases. Furthermore it is known that cobalt, rhodium and iron carbonyls, under the reaction conditions applied, are able to abstract hydrogen from alcohols, amines and even from the unreactive cycloparaffins to form metal hydrocarbonyls [121-124]. 

Methanol hydrocarbonylation can also be carried out with Fe(CO)5/NR3 [58] and Ru/I [59] catalysts, although rates are much lower than with cobalt systems. In the case of the iron/amine catalyst CO2 is formed instead of water as the by product ... 

---