Pentacarbonyl iron Fe

Other examples are iron pentacarbonyl, Fe(CO)s, and chromium hexacarbonyl, Cr(CO)(j, which have trigonal bipyramidal and octahedral configurations respectively. 

Two compounds associated with particular industrial risks are iron(III) oxide, Fe202, and iron pentacarbonyl, Fe(CO). Chronic inhalation of iron(III) oxide leads to siderosis. Adequate ventilation and mechanical filter respirators should be provided to those exposed to the oxide. Iron pentacarbonyl is volatile and highly toxic. 

Like some other d-block metals, such as nickel, iron can form compounds in which its oxidation number is zero. For example, when iron is heated in carbon monoxide, it reacts to form iron pentacarbonyl, Fe(CO)5, a yellow molecular liquid that boils at 103°C. 

Of course, commercially available transition metal complexes are stable at room temperature because they have achieved an 18-electron noble gas-like electronic configuration. Thus, molecules like iron pentacarbonyl [Fe(CO)s], ferrocene [Fe(C5H5)2], as well as piano-stool complexes such as C5H5Co(CO)2 are chemically quite inert. In order to study bimolecular reactions, it is necessary to first prepare unsaturated complexes. For studies using molecular beams, one approach is through photolysis of a stable volatile precursor in a supersonic nozzle. 

Thermal decomposition of iron pentacarbonyl. Very finely divided red iron oxide is obtained by atomizing iron pentacarbonyl, Fe(CO)5, and burning it in excess of air. The size of the particles depends on the temperature (580-800 °C) and the residence time in the reactor. The smallest particles are transparent and consist of 2-line ferri-hydrite, whereas the larger, semi-transparent particles consist of hematite (see Chap. 19). The only byproduct of the reaction is carbon dioxide, hence, the process has no undesirable environmental side effects. Magnetite can be produced by the same process if it is carried out at 100-400 °C. Thermal decomposition of iron pentacarbonyl is also used to coat aluminium powder (in a fluidized bed) and also mica platelets with iron oxides to produce interference or nacreous pigments. 

UFPs of the Fe-N system can be synthesized from iron pentacarbonyl Fe(CO)s] and NH3 as reactants by a IOOO-W continuous wave C02 laser irradiation. The NH, gas is the absorbent of the laser beam in this case. At the lower synthesis temperature, below 650°C, UFPs of y -Fe4N with particle size of 10-25 nm grew dominantly. Above 1150°C, however, the growth of y-Fe UFPs with larger particle size of 30-100 nm was predominant (73). Iron carbonitride (lCN) UFPs were also synthesized from the ternary reactants of Fe(CO)s, NH3, and C2H i. The structure oflCN UFPs was hexagonal with e-Fe3(N,C) phase. A large saturation magnetization up to 142 emu/g was obtained and was ascribed to the carbon layer on 1CN UFPs (74). 

The purpose of this exercise is to investigate the effect of an inert (CO2) and a chemically active agent (iron pentacarbonyl, Fe(CO)s) on the flame speed of an atmospheric, stoichiometric methane-air flame. Employ a laminar premixed flame code to determine the flame speed, using GRI-Mech extended with a subset for iron pentacarbonyl chemistry [344] (GRIMFe.mec). 

Especially characteristic were the tricarbonyl derivatives M(CO)3L3 (L = amine, NH3, etc.), but tetra- and pentacarbonyl compounds were also discovered. Recently, even dicarbonyls M(CO)2(L—L)2 and fully substituted derivatives M(L—L)3 and M(L—L—L)2 (L—L = dipyridyl, o-phenanthroline L—L—L = tripyridyl) have been synthesized from the hexacarbonyls by my former co-worker H. Behrens (5). Monosubstituted derivatives of iron pentacarbonyl Fe(CO)4L (L = NH3, amines, etc.) have been identified relatively recently (6). 

Carbon monoxide has been found to be surprisingly reactive toward the metals in Group VIII, in both their oxidized and unoxidized states. A sizable number of compounds exist in which one or more CO molecules are attached to a metal atom through the carbon typical of these are nickel tetracarbonyl, Ni(CO)4, iron pentacarbonyl, Fe(CO) cobalt carbonyl hydride, Co(CO)4H platinum carbonyl chloride, Pt(CO)2Cl2 and more complicated molecules such as Co4(CO)i2. 

Iron pentacarbonyl, Fe(CO)5, was obtained by Mond and Langer by allowing finely divided iron, obtained by reduction of ferrous oxalate in a current of hydrogen, to remain twenty-four hours in an atmosphere of carbon monoxide. The gas was gradually absorbed, and, on warming the whole to 120° C., the carbonyl distilled over and condensed in a tube kept at — 20° C.1... 

Iron pentacarbonyl (Fe(CO)s) may be photooxidized in a similar maimer. Although no fewer than five distinct iron carbonyl intermediates are seen, there is no sign of any photoselectivity in this reaction sequence. It is possible, however, to bmld up reasonable concentrations, at least of the early intermediates, by carefiilly controlling the time of photolysis. Hence, it appears that the first oxidation product is (jj -02)Fe(C0)4, where the O2 ligand occupies a basal site in a square pyramidal framework (33). 

Palchik [182] obtained nanosized amorphous iron oxide (Fe203) by the pyrolysis of iron pentacarbonyl, Fe(GO)5, in a modified domestic microwave oven in refluxing chlorobenzene as solvent under air. The reaction time was 20 min. Separate particles of iron oxide, 2-3 nm in diameter, were obtained together with aggregated spheres with a diameter of 25-40 nm. Differential scanning calorimetry measurements showed an amorphous/crystalline phase transition at about 250 °C. 

The gas-phase reactions of lanthanide (Ln+ = La+-Lu+, except Pm+) cations with iron pentacarbonyl, Fe(CO)s, and with ferrocene, Cp2Fe, have been studied by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR/ MS). In the case of Fe(GO)s, the observed primary products were of the type LnFe(CO)x+ (Ln = La, Ce, Pr, Nd, Gd, Tb v = 3 Ln = Ho, Er, Lu x = 3 and 4 Ln = Sm, Eu, Dy, Tm, Yb x = 4), and evidence was obtained for the presence of direct Ln-Fe bonds in these species. With Cp2Fe the majority of the Ln+ cations reacted by metal exchange, yielding Ln bis(cyclopentadienyl) ions Cp2Ln+, while the less reactive Ln+ cations formed the adduct ions LnFeCp2+.851... 

Aminomethylation of alkenes. The original procedure of Reppe for aminomethyla-tion of alkenes (equation 1) employed iron pentacarbonyl, Fe(CO)5 (1,519-520 2,229 230 3, 167), as catalyst. Iqbal2 now finds that rhodium oxide is a far more effective... 

When Fe is heated in CO, it reacts to form trigonal-bipyramidal iron pentacarbonyl, Fe(CO)s, a yellow molecular liquid that melts at -20°C, boils at I03°C, and decomposes in visible light. 

Metal carbonyls, especially nickel carbonyl, Ni(CO)4, and iron pentacarbonyl, Fe(CO)5, are extremely hazardous species. They are volatile and readily taken into the body through the respiratory tract or through the skin. The carbonyls affect tissue directly and they break down to toxic carbon monoxide and products of metal, which have additional toxic effects. 

Iron(iii) oxide, a-Fe203, is used as a beam splitter and interference layer in optical devices [10]. a-lron(iii) oxide can be prepared by CVD using iron pentacarbonyl, Fe(CO)5 (10), as a precursor [55, 56]. The decomposition of ferrocene, Cp2Fe, (11) at... 

There is a large class of iron organometallic compounds which can be described as molecular, diamagnetic, and highly covalent. They are derived in the main from the parent compounds iron pentacarbonyl, Fe(CO)s, and the cyclopentadienyl complex ferrocene, (jr-CsHslaFe or CpaFe. In view of their large numbers, it is not surprising that considerable Mossbauer spectral data are available, but as we shall now see the interpretation of this data introduces considerable problems. 

The carbonization of pure organic compounds such as carbazole, phenazine, acridine (for formulas, see Figure 7.2) has also been studied under 7.5 Mbar argon pressure [23], Volatile compounds such as benzene, pyridine, pyrazine, quinoline, and phenazine have been calcined at 1073 K in sealed quartz glass tubes [24], Bent carbon nanotubes and coils with a nitrogen content of about 1% were formed when pyridine, 5-methylpyrimidine, or i-triazine (see Figure 7.2) were decomposed on small catalytic cobalt particles at 1123 or 1373 K [25], Carbon nanotubes with about 2% N were produced in excellent yield and free of other carbon materials by pyrolysis of pyridine vapor at 1373 K in an argon stream with admixed iron pentacarbonyl, [Fe(CO)s] [26], In another study, pyrrole vapor has been catalytically decomposed on nickel sheets at 1073 K [27],... 

An interesting approach to synthesize metal alloy nanocrystals is the use of simultaneous salt reduction and thermal decomposition processes. Sun et al. [18] reported on the synthesis of iron-platinum (FePt) nanoparticles through the reduction of platinum acetylacetonate by a diol, and decomposition of iron pentacarbonyl (Fe(CO)5) in the presence of a surfactant mixture (oleic acid and oleyl amine). On the basis of a similar approach, Chen and Nikles [217] synthesized ternary alloy nanoparticles (FC cCo3,Ptioo x-y), using a simultaneous reduction of acetylacetonate and platinum acetylacetonate and thermal decomposition of Fe(CO)5 and obtaining an average particle diameter of 3.5 nm and narrow particle size distribution. 

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