Iron carbonyl compounds

The lethal effects of carbon monoxide on hemoglobin had been analyzed by Claude Bernard and shown to be due to the formation of an iron-carbonyl compound. In 1891 Mond and Langer showed that iron pentacarbonyl could be dissociated by light, and in 1897 J.S. Haldane and J.L. Smith found light would decompose the carbonyl compound of hemoglobin. Other metal carbonyls are not photodecomposed. 

The reactions of a number of iron carbonyl compounds with [(PhPCH2-CH2]2PPh (Pf.PfiPf) are summarized in Table 2. Fe(CO) l2 reacts with the... 

Table 2 The reaction off Pf.Pf.Pf) with iron carbonyl compounds Reactant Product Mode of bonding...

Sarel and co-workers have examined some reactions of alkynylcyclopropanes with iron carbonyl compounds [1]. Treatment of cyclopropylacetylene (5) with iron pentacarbonyl under photolytic conditions gives, after cerium(IV) oxidation, isomeric quinones 6 and 7, derived from two molecules of 5 and two carbonyls with both cyclopropane rings intact [6]. Furthermore, the photoreaction of dicyclopropylacetylene (8) with iron carbonyl gives some ten different products depending on the reagents and the reaction conditions, and some of them have the cyclopentenone skeleton formed by the opening of cyclopropane ring coupled with carbonyl insertion [7] (Scheme 2). 

Tetraethylammoniumhis(tetracarbonyliron)bis(/i-tetracarbonyliron)dithal-late(2 — ), [Et4N]2[Tl2Fe4(CO)16], decomposes rapidly upon exposure to air and is soluble in MeOH, CH2C12, and most polar organic solvents. Its crystal structure shows it to be a weak dimer of [Tl Fe(CO)4 2] and it probably exists as the monomer in solution.15 IR (CH2C12, cm-1) 1985(m), and 1908(s). It may be oxidized or irradiated to yield higher nuclearity thallium-iron carbonyl compounds.14,15... 

Most examples in the literature on hydrosilylation with iron complexes as catalyst concern Fe(CO)5 or related iron carbonyl compounds [41]. The first use of iron pentacarbonyl was reported for the reaction of silicon hydrides with alkenes at 100-140 °C to form saturated and unsaturated silanes according to Scheme 4.20 [42, 43]. 

Hydrosilylation reactions catalyzed by iron carbonyl compounds often occur under drastic thermal conditions. Schroeder and Wrighton reported a photocatalyzed reaction oftrialkylsilanes with alkenes in the presence of Fe(CO)5 at low temperatures (0-50 °C) [48]. It is well known that irradiation of mononuclear metal carbonyls leads... 

My co-worker H. Beutner (95) was able to isolate from a nitrite-containing carbonylferrate solution, in trace amounts only, a binuclear nitrogen-atom-bridged iron carbonyl compound. This complex is now obtained in good yield by UV irradiation of the reaction solution and was identified mass spectrometrically as di-/x-amino-bis(tricarbonyl)iron, (OC)3Fe(NH2)2Fe (C0)3. The group... 

Cyclic diazo compounds are known to form mononuclear cr-complexes with iron carbonyl compounds, which further react to give more stable binuclear complexes containing an Fe-Fe bond <1976TCC105>. However, such complexes are rare in the case of cyclic four-membered diazo compounds. No new examples have been reported in the last decade. For more informations, CHEC-II(1996) should be consulted <1996CHEC-II(1B)911>. 

Reactions of this type have been reported tor reactions of a,a -dibromoketones with iron carbonyl compounds or zinc-copper couple as catalysts (4, 157-158 5, 221-224). 

The tungsten complex 509j leads to a dimer containing an M—M bond, 511 (2S6). The selenium and tellurium Iron carbonyl compounds (512)... 

EINECS 236-670-8 FER pentacarbonyle HSDB 6347 iron carbonyl Iron carbonyl (Fe(CO)6) Iron carbonyl (Fe(CO)5), (TB-5-11)- Iron carbonyl, (Fe(CO)5) Iron carbonyl, (TB-5-11)- Iron carbonyl compounds Iron pentacarbonyl Pentacarbonyliron UN1994,... 

Aside from the thermal and photochemical activation of Fe(CO)5 and related iron carbonyl compounds, the field of iron catalyzed hydrogenation lay mostly dormant for decades. As outhned in the previous section, comprehensive follow-up papers on Fe(CO)5 chemistry had appeared but few new metal-ligand platforms for cata-... 

One system that Professor Rose-Petruck has been investigating involves the reactions of the iron carbonyl compound Fe(CO>5 in solution. He and his students have found that Fe(CO)5 rearranges in solution in a way that allows a solvent molecule to directly attach to the iron atom. This knowledge is important in understanding how Fe(CO)5 and similar compounds react in solution. 

Iron carbonyl compounds turned out to be very promising precursors for organometallic iron Tp complexes. 

Isomerization of the double bond has been observed in some cases on reaction with iron carbonyl compounds (4). However, no evidence for isomerization was observed in this case. The starting material was recovered unchanged in 28% yield. This fact suggests that the position of the double bonds in ero sterol is a stable one. The compound was found to have optical activity, [odj) -77,2 (AcOEt) the value can be compared with that of ergosterol, [(x]q -135 . 

Linear p yenes containing more than four double bonds have not been investigated for the formation of tt -complexes. The reaction of vitamin A acetate, which contains five conjugated double bonds, with iron carbonyl compounds is thus of interest. 

Caution Owing to the extreme toxicity of iron carbonyl compounds, care must be taken when preparing and handling the compounds. All work should be carried out in a well ventilated hood. 

The largest group of diene complexes which have been investigated are iron carbonyl compounds. When 1,3-butadiene reacts with Fe lCO), the initial product is a labile f/ -complex, which readily loses carbon monoxide to yield (f/ -C4Hg)Fe(CO)3. Butadiene(tricarbonyl)iron is a yellow, essentially air stable complex, m.p. 19 "C. It was first prepared by Reihlen in 1930 by heating FeiCO), with butadiene in a tube under pressure, but this was an isolated discovery which did not arouse much interest at the time. On account of the ease of preparation and handling of these diene complexes, however, an enormous amount of work has been done in this area since the late 1950s. Only modest precautions are required to protect solutions from oxidation and some operations can be carried out even in air. 

Unconjugated dienes are readily brought into conjugation in the presence of iron carbonyl compounds. Usually, the less sterically crowded of the pos-... 

Most of the nitro eompounds reactions reported to be promoted by iron carbonyl compounds are stoichiometric reductions to anilines, although some reactions affording azo-, azoxybenzenes or carbamates have also been reported (see Chapters 3 and 4). Catalytic reactions have been reported in only very few cases, and always with very low turnovers. This lack of stability of the catalytic systems appears to be due to the easy formation of iron oxides [229]. The last reaction can be partly retarded by adding the nitro compound slowly to the reaction mixture, but only about ten turnovers were anyway obtained even under these conditions [230]. 

Later, Hieber and Pack also prepared some iron carbonyl compounds containing zinc, cadmium, or mercury [75]. 

The iron carbonyl complexes are most easily obtained via reaction of a suitable salt of [Fe(CO)4] and an appropriate dihalo-group 13 element complex X2ER, but reaction of a neutral iron carbonyl compound with (RE) may also be used. The syntheses of the known Fe(CO)4 compounds arc presented in Equations (11)-(14). The R group attached to E can also be a donor ligand such as tris(pyrazolyl)borate (Equation (14)). ... 

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