Iron pentacarbonyl, with

Figure 9.5 Surface organometallic chemistry of iron pentacarbonyl with alumina hydroxyl groups.

A recently described method for insertion of a carbon monoxide molecule into the monoepoxide of a conjugated diene gives /3-lactones in high yield. This is achieved by reaction of iron pentacarbonyl with the starting vinyloxirane to give the 7r-allyl iron complex (66), which on oxidation with cerium(IV) ammonium nitrate gives the /3-lactone. In some cases, y-Iactone products can also be obtained from this reaction (8lJCS(Pi)270). 

Direct reaction of iron pentacarbonyl with trimethylsilyl isocyanide ( C=N—SiMe3) at 65°-75° yields an air-sensitive substitution product Me3Si—N=C Fe(CO)4 in 93% yield, with elimination of carbon monoxide (152). It was shown by infrared spectroscopy (38) that complex formation lowers the N=C bond order for Me3Si—N=C , whereas it raises the N=C bond order for Me3C—N=C , presumably as a result of interaction between dv orbitals of silicon with the metal d orbitals. 

A less conventional preparation of isocyanide complexes involves the reaction of iron pentacarbonyl with metalated (sodium or lithium derivative) hexamethyldisilazane (162). 

A recent review has highlighted the extensive and interesting chemistry of metal isocyanide complexes.1 Although synthetic procedures are varied, a vast number are based on substitution in metal carbonyl complexes by isocyanides. Such procedures are, however, not always successful. This is especially so in cases where multiple substitution of CO is required, as in the syntheses of homoleptic isocyanide complexes. Many of the inherent difficulties are illustrated by the reaction of iron pentacarbonyl with isocyanides. 

A remarkable cationic iron carbonyl is formed by the reaction of iron pentacarbonyl with chloro or bromo azide, [Fe2(CO)4(N3)2]2+ (180). This cation has the highest recorded paramagnetism for a metal carbonyl of 5.29 /xB. A planar (D2f,) structure is proposed the azido groups are bridging and the carbonyls are terminal. 

Several preparations of dicarbonyl dinitrosyl iron have been reported including treatment of [Fe3(CO)i2] or [Fe2(CO)9] with nitric oxide,86,87 acidification of a mixture of [HFe(CO)4]- and nitrite ion,88 reaction of iron pentacarbonyl with nitrosyl chloride89 and acidification of a mixture of [Fe(CO)3NO]- and nitrite ion90 as in equations (2) and (3). 

In contrast, reaction of bromophenylacetylene 263 and iron pentacarbonyl with diarylcar-bodiimides at 90-100 °C gives benzodiazepinone derivatives 264.2 ... 

On shaking iron pentacarbonyl with a dilute solution of hydrogen peroxide, colloidal ferrous hydroxide separates. 

The reaction of iron pentacarbonyl with alkyl or phenyllithium gives acyltetracarbonylferrates, which react in situ with diaryliodonium salts to afford moderate to good yields of arylketones. ... 

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. ... 

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) ... 

That aldehydes are indeed reduced to alcohols under reaction conditions was shown by adding benzaldehyde to a solution obtained by treating iron pentacarbonyl with aqueous alkali prepared according to Equation... 

A,ii, Cyclopentadienylirondicarbonyl (Fp) Compounds. A common organoiron reagent is cyclo-pentadienylbis(carbonyliron) (Fp, 711). " This derivative can be converted to an alkyl derivative (713, where R = alkyl) by reaction with an alkyl halide, or to the protio derivative (713, R = H) by reaction with an acid. The anionic reagent 712 is prepared by reaction of iron pentacarbonyl with the dimer of cyclopentadiene (710 - sec. 115.B) at 200°C to give the dimeric species 711. Treatment of 711 with base leads to loss of cyclopentadiene and formation of 712. A byproduct of this process is ferrocene (71 4) formed by extrusion of carbon monoxide from 711.595... 

The only practical preparations of cyclopentadienyliron dicarbonyl dimer involve reactions of iron pentacarbonyl with either cyclopentadiene or its dimer at elevated temperatures. Although the use of monomeric cyclo-pentadiene is reported to give a higher yield and possibly a purer product, use of an autoclave is required because of the low boiling point of cyclopentadiene if a reasonable amount of product is to be prepared. For this reason the reaction between iron pentacarbonyl and dicyclopentadiene may well be more convenient since it can be carried out in an open system. The preparation described below involves dicyclopentadiene. 

Triiron dodecacarbonyl has been obtained by three different methods the action of heat on the iron carbonyl Fe2(CO)9, oxidation of the anion HFe(CO)4 by various oxidizing agents, and treatment of iron pentacarbonyl with triethylamine followed by acidification of the reaction mixture. The method described below is based on the oxidation of the anion HFe(C0)4 with manganese dioxide. 

I eaelion differs from the reaction of iron pentacarbonyl with the same substrates in lhat monoketones, RCOCH3, are the major products. 

Examples of carbonyl insertion reactions involving compounds of Group VIII metals are more common. The reaction of iron pentacarbonyl with the cyclopropylalkene (41) involves both carbonyl insertion and cyclopropane ring opening. Reduction of cobalt(n) to cobalt(o) in aqueous ammonia is thought to involve a carbonyl insertion stage, with... 

Iron carbonyl complexes are obtained by irradiation of iron pentacarbonyl with vinylcyclopropanes. The principal modes of reaction are (i) metal insertion into a strained bond with hydrogen migration to give diene-Fe(CO)3 complexes, (ii) metal carbonyl insertion to give a n-allyl-complexed acyl iron tricarbonyl, and (iii) cycloinsertion of CO across the homodiene to give a cyclohexenone. Similar types of... 

Treatment of iron pentacarbonyl with liquid ammonia gives (NH4)2 [Fe(CO)4] (22). Treatment of iron pentacarbonyl with aqueous ammonia in the presence of pyridine (15) or hydroxylamine 14) gives [Fe(NH3)fi] [Fe2(CO)J. 

Treatment of Fe3(CO)i2 with pyridine JV-oxide in benzene at room temperature gives the brown pyrophoric [Fe(CsH5NO)4][Fe4(CO)i3] IS). Irradiation of iron pentacarbonyl with dimethylsulfoxide in benzene solution at 80° C gives the red-black, slightly air-sensitive [Fe(Me2SO)e] [Fe4(CO) 13] 18). Irradiation of iron pentacarbonyl with triphenylphosphine oxide or triphenylarsine oxide in benzene solution at 80° C gives dark red materials formulated as [Fe((/>3PO)2][Fe2(CO)g] and [Fe( 3AsO)3][Fe2 (CO)g], respectively 18). The apparently low coordination numbers of two or three for the cationic iron atoms in these two compounds seem peculiar. 

Treatment of iron pentacarbonyl with nitrite ion at 25-40° C in methanol solution 81)... 

The reaction of iron pentacarbonyl with l,4-diazabicyclo[2.2.2]-octane with UV irradiation produced the mononuclear iron carbonyl complex 30 (Scheme 28).Subsequent irradiation of 30 with additional Fe(CO)s resulted in a complex with two Fe(CO)4 fragments 31. 

A chiral ftilvene dicarbcn lcyclopaitadiaiyl dimer has been ]nq red by reacting iron pentacarbonyl with 6-dimed lamino-fiilvene [Fe2 n >b Me2NCHCHC3H3CHCsH4 (CO)s] is al ) fcHtned. Hie kinetic resolutitm of [Q>Fe(C0)PHi3C(0)CH3] using aldol reactions with canqihor has been achieved. ... 

All hydroperoxides, peroxy acids, peroxy acid esters, and diacyl peroxides give a positive reaction with iron pentacarbonyl with the evolution of heat and CO2 and Fe203 separation ... 

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