Alkali metal iron carbonylates

Alkali metal iron carbonylates. An aqueous alcoholic solution of KHFe(CO)4 can be prepared from iron pentacarbonyl (1 mole) and KOH (3 moles). A THF solution of NaHFe(CO)4 can be prepared by the reaction of iron pentacarbonyl with sodium amalgam and then with water (1 mole). Amines can be alkylated by aldehydes in the presence of these reagents. One advantage of this procedure is that primary amines can be converted into either monoalkyl or dialkyl derivatives. ... 

Metals with large negative potentials, like alkali metals and calcium, are able to reduce almost anything, even carbon-carbon double bonds. Metals with low potentials (iron, tin) can reduce only strongly polar bonds (such as nitro groups but, generally, not carbonyl groups). 

The kinetics of this reaction have been studied in detail and a hydroxy-carbonyl is specifically proposed as an intermediate consistent with the kinetic data. Decomposition of this intermediate hydroxycarbonyl may proceed by -elimination of the platinum hydride product since the hydroxycarbonyl is a 16-electron coordinatively unsaturated complex. Another well-known example of metal hydride formation from CO and H20 is the reaction of iron carbonyl in aqueous alkali (55) (36). 

Rare earth oxides are useful for partial oxidation of natural gas to ethane and ethylene. Samarium oxide doped with alkali metal halides is the most effective catalyst for producing predominantly ethylene. In syngas chemistry, addition of rare earths has proven to be useful to catalyst activity and selectivity. Formerly thorium oxide was used in the Fisher-Tropsch process. Recently ruthenium supported on rare earth oxides was found selective for lower olefin production. Also praseodymium-iron/alumina catalysts produce hydrocarbons in the middle distillate range. Further unusual catalytic properties have been found for lanthanide intermetallics like CeCo2, CeNi2, ThNis- Rare earth compounds (Ce, La) are effective promoters in alcohol synthesis, steam reforming of hydrocarbons, alcohol carbonylation and selective oxidation of olefins. 

All the simple carbonyl hydrides (Table IY) may be readily prepared by acidification of alkali metal salts derived from the simple carbonyls. Only the carbonyl hydrides of Mn, Re, Co, and Fe are well characterized. They form highly toxic volatile liquids and are unstable thermally and with respect to oxidation. Pentacarbonylmanganese hydride is stable to light and air for several hours at room temperature (173), while the very unstable cobalt and iron complexes decompose spontaneously at — 20°C (167, 251). It may be noted that solutions of these carbonyl hydrides in inert solvents undergo spontaneous decomposition much more slowly than the pure substances. 

Chemiluminescence and photoluminescence in diatomic iron oxide, Rb2, and alkali-metal dimers with halogen atoms and metal vapour-oxidant flames,202 203 lifetime measurements of selectively excited states of diatomic hydrides,204 photodissociation of alkali-metal halide vapours,206 spin-orbit relaxation of the HTe ( 2IIi) radical,20 the photodecomposition of metal carbonyl anions such as [Mn(C04)] in the vapour phase,207 and the fluorescence of Rhodamine 6G in the vapour phase 208 have been studied in recent reports. In the last study it was concluded that an insufficient concentration of the fluorescing dye could be maintained in the vapour phase to permit laser action to occur. 

Within this context, the present article concentrates on transition metal cluster complexes of cobalt, iron and manganese with mixed chalcogen/carbonyl ligand spheres obtained by reaction of simple binary metal carbonyls with alkali-metal sulfides, alkali-metal thiolates or transition-metal thiolate complexes and their selenium or tellurium counterparts. 

Conjugate reduction of enones. The alkali metal carbonylchromates reduce a, -unsaturated carbonyl compounds to the corresponding saturated carbonyl compounds in 4d-807o yield. They are comparable to potassium hydridotetra-carbonylferrate (6, 483-486), but are simpler to prepare because chromium hexacarbonyl is a stable solid and less toxic than iron pentacarbonyl. Examples ... 

Reduction of nitro compounds to amines is a synthetically important reaction (98) and is practiced since the birth of modern chemical industry—many aromatic amines are key intermediates in production of dyes and pesticides. However, the stoichiometric reductions using iron or alkali metal hydrogen sulfides or catalytic hydrogenations with heterogeneous catalysts leave room for improvements in selectivity, especially with reference to halonitro-derivatives. There are many homogeneous catalysts such as the rhodium carbonyls in the presence of amines or chelating diamines, or [Rus(CO)i2] in basic amine solutions that are... 

Other isocyanate syntheses that have recently been reported include several well-known reactions. One area which has attracted considerable attention is that of the direct production of isocyanates by the carbonylation of nitro-arenes. Both mono- and di-isocyanates are claimed to have been produced using various catalysts palladium, rhodium, and iron compounds often being cited. Other preparative reactions for isocyanates which have appeared in the literature include the acid catalysed hydrolysis of isocyanide dihalides and the reaction between alkyl halides and alkali-metal cyanates, although the latter has been given a modern flavour by the use of a polymer-supported reagent. ... 

This is the earliest method used for the preparation of alkali metal and other derivatives of metal carbonyl anions. In 1931 the reaction between iron pentacarbonyl and aqueous hydroxide ion to give the [Fe(CO)4] " anion was first described (2). Since that time the reactions between hydroxide ion and various metal carbonyl derivatives have been used to prepare a variety of anions, as illustrated by the following equations. 

Several anionic carbonyl derivatives of iron have been obtained by treatment of the three carbonyls of iron, Fe(CO)5, Fe2(CO)9, and Fe3(CO)i2, with alkali metals, hydroxide ion, or nitrogen bases. 

Substances that catch fire spontaneously in air without an ignition source are called pyrophoric. These include several elements— white phosphorus, the alkali metals (group lA), and powdered forms of magnesium, calcium, cobalt, manganese, iron, zirconium, and aluminum. Also included are some organometallic compounds, such as ethyllithium (LiC2H5) and phenyllithium (LiQHj), and some metal carbonyl compounds such as iron pentacarbonyl, Fe(CO)5. Another major class of pyrophoric compounds consists of metal and metalloid hydrides, including lithium hydride, LiH ... 

Lower valent tungsten halides are a new class of deoxygenation agents, e.g. for the conversion of carbonyl or epoxy compounds into olefins . A new reagent, generated in situ from iron pentacarbonyl and a small amount of base in moist solvents, selectively and efficiently hydrogenates the ethylenic portion of a,/ -unsaturated carbonyl compounds, such as ketones or lactones, under mild conditions. Aliphatic tert. amides can be easily reduced to alcohols by alkali metals in hexa-methylphosphoramide and a protic cosolvent such as tert-butanol. Aldehydes can be obtained from acids by catalytic reduction of intermediate carboxylic alkoxyformic anhydrides . Sec. nitro compds. are converted into ketones by the joint action of a nitrite ester and NaNOg under mild, non-acidic conditions . 

W hen alkali metal salts of iron carbonyl 98,99) are treated with perfluoro-acyl halides the intermediate acyl compounds are not isolated. 

Metals can also be introduced by adsorption of the elemental vapor or melt, for instance in the case of mercury or alkali metals. Adsorption of molecular "precursors such as carbonyls of iron, cobalt, nickel and molybdenum, and subsequent thermal or photochemical decomposition has become an important approach for metals that are difficult to reduce. Other ligands such as alkyls or acetylacetonates have also been used for this purpose. In all these cases, thermal decomposition carries the risk of excessive mobility of the precursors or intermediates such that agglomeration and particle formation at the external surface of the zeolite crystals can occur. Barrer has described the synthesis of salt-bearing zeolites including the famous dry synthesis of ultramarin in 1828, which is sodalite containing intercalated Na-polysulphides. Adsorption of numerous non-ionic and salt species into zeolites was also described, either as such or as precursors for oxides, hydroxides, or metals. 

The carbonyls are in general volatile compounds with an extensive chemistry which presents many problems as regards valence and stereochemistry. Some are reactive and form a variety of derivatives, as shown in Chart 22.1 for the iron compounds, while others are relatively inert, as for example, Cr(CO)6 etc. and Re2(CO)iQ. This rhenium compound, although converted to the carbonyl halides by gaseous halogens, is stable to alkalis and to concentrated mineral acids. A few carbonyls may be prepared by the direct action of CO on the metal, either at atmospheric pressure (Ni(C0)4) or under pressure at elevated temperatures (Fe(CO)s, Co4(CO)i2)- Others are prepared from halides or, in the case of Os and Re, from the highest oxide. The polynuclear carbonyls are prepared photo-synthetically, by heating the simple carbonyls, or by other indirect methods. 

The best catalyst was found to consist of zinc oxide and copper (or copper oxide) with an admixture of compounds of chromium. The success of the operation depended upon (a) the absence of alkali, which would cause decomposition of the methanol and the production of higher alcohols and oily products, and (b) the complete elimination of all metals except copper, aluminum and tin from those parts of the apparatus which come in contact with the reacting gases. Contact of carbon monoxide with iron, nickel, or cobalt had to be avoided since they formed volatile carbonyls winch deposited metal, by decomposition, on the active catalyst surface and thereby acted as poisons to destroy activity. 

The crystal structure of Na2[Fe(CO)4]-f dioxane (22a) reveals one set of Na+ --OC interactions, at 2.32 A, to four CO oxygens from four different [Fe(CO)4]2 units. These Na+ ions also are coordinated to two dioxane molecules (Fig. 6). [A similar type of coordination about Na+ is observed in [Na(thf)2]2[Zn(Fe(CO)4)2], (22b).] A second set of Na+ ions protrude into the distorted tetrahedron (Fig. 7). In this case the Na+ has rather long contacts with two carbon atoms (3.05 and 2.86 A) and the iron (3.09 A). The Fe—C—O angle (171°) appears to be somewhat distorted, and the C—Fe—C angles (129.7°) deviate markedly from the tetrahedral angle. The first set of Fe—C—O—Na interactions found in this structure are of the I —CO— type and are analogous to those discussed above for the contact ion pairs in solution. The second type of interaction with the carbonyl carbon and metal may be analogous to the direct interaction between an alkali or alkaline earth metal ion and a transition metal which has been invoked as a possible solution species. 

Their use in the laboratory is well known. Very pure iron (e.g., carbonyl iron) and pure nickel, and sometimes also high-grade alloy steels, serve as crucible and boat materials. In particular, they are resistant to liquid and gaseous alkali and alkaline earth metals at high temperatures. 

Reaction on a zero oxidation state iron matrix (iron powder) proceeds analogously, with formation of [Fe(L588)] [427]. Zinc(II) tetrabenzoporphinate [Zn(L588)j can also be obtained by interaction of potassium phthalimide with malonic acid or sodium acetate in the presence of zinc(II) acetate [428], as well as by template condensation of isoindolene with a carbonyl component, such as mesoxaUc acid hydrate, paraform, diphenylformamide, or A -methylformanilide at 300-360 C and in the presence of alkali [429]. On treatment of [Zn(L588)] with mineral acid, demetallation takes place with the release of metal-free porphin. This may be then used for synthesis of tetrabenzoporphynates of those metals which are not effective as template agents [427]. 

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