From pentacarbonyliron

ONE-POT SYNTHESIS OF DICARBONYLTRIS(PHOSPHANE)IRON(0) COMPLEXES FROM PENTACARBONYLIRON... 

Pentacarbonyliron is a stable 18-electron complex of trigonal-bipyramidal geometry and represents the primary source of most organoiron complexes. Nonacarbonyldiiron is prepared in a photolytic reaction from pentacarbonyliron. Dodecacarbonyltriiron can be obtained from nonacarbonyldiiron by a thermal reaction. Both, nonacarbonyldiiron and dodecacarbonyltriiron, contain metal-metal bonds. They are slowly degraded to give pyrophoric iron and therefore should be handled with care. 

The first aspect is illustrated by the synthesis of tricarbonyl(ri4-l,3-diene)iron complexes from pentacarbonyliron in the presence of catalytic amounts of a 1-azabuta-... 

Most of the preparations of molecular coordination compounds of iron published in Inorganic Syntheses or elsewhere require the readily available pentacarbonyliron or derivatives thereof. However, pentacarbonyliron is a rather stable compound that needs either thermal or photochemical activation to react. We describe here the selective, high-yield, one-pot synthesis of the title complexes from potassium tetracarbonylhydridoferrate(l — ), easily generated from pentacarbonyliron, a method that can be referred to as a nucleophilic activation of pentacarbonyliron. ... 

DICARBONYL-m-DIHYDRIDO-rrfl/is-BIS(PHOSPHITE)IRON(II) COMPLEXES ONE-POT SYNTHESES FROM PENTACARBONYLIRON... 

Acyltetracarbonylferrates, prepared from pentacarbonyliron and an alkyl-lithium, react with diaryliodonium salts to give ketones " pentacarbonyliron also reacts with alkyl halides in the presence of a phase-transfer catalyst to give the ferrate anion (38), which on addition of a second alkyl halide yields unsym-metrical ketones [equation (9)]/"... 

Scheme 4-1. Generation of disodium tetracarbonylferrate from pentacarbonyliron and sodium.

Scheme 4-2. In situ formation of Collman s reagent from pentacarbonyliron or iron(III) chloride and reaction with alkyl halides.

Alternatively, disodium tetracarbonylferrate can be conveniently generated in situ from pentacarbonyliron, sodium and naphthalene instead of benzophenone (Scheme 4-2, eq. 1) or by treatment of iron(III) chloride with sodium naphthalenide in tetrahydrofuran in a carbon monoxide atmosphere (Scheme 4-2, eq. 2). The Collman s reagent thus obtained is directly reacted with electrophiles such as organic halides to give anionic acyliron complexes (Scheme 4—2, eq. 3). The latter can be easily transformed into... 

Cyclohexadiene Series. Tricarbonyliron complexes are formed by reaction of Fe(CO)4 with dienes. Fe2(CO)9 is an important starting material for this reaction because it offers a convenient source of Fe(CO)4 generated under much milder conditions than from pentacarbonyliron (eq 2). 

Anionic Iron Carbonyl Reagents. The reagent [HFe(CO)4] can be generated in situ from pentacarbonyliron, allowing straightforward, regiocontrolled, hydroxycarboxylation of acrylic acid by Fe(CO)s, Ca(OFI)2, and H20/i-PrOH under 1 atm of CO. ... 

The solvent and excess pentacarbonyliron are removed under reduced pressure and the product is recrystallized from dichloromethane-hexane. Yield 3.56 g (83% based on consumed pentacarbonyliron). 

Addition of nucleophiles to a carbon monoxide ligand of pentacarbonyliron provides anionic acyliron intermediates which can be trapped by electrophiles (H+ or R—X) to furnish aldehydes or ketones [18]. However, carbonyl insertion into alkyl halides using iron carbonyl complexes is more efficiently achieved with disodium tetracarbonylferrate (Collman s reagent) and provides unsymmetrical ketones (Scheme 1.2) [19, 20]. Collman s reagent is extremely sensitive towards air and moisture, but offers a great synthetic potential as carbonyl transfer reagent. It can be prepared by an in situ procedure starting from Fe(CO)5 and Na-naphthalene [20]. 

The classical protocol for synthesis of iron-diene complexes starts from the homoleptic pentacarbonyliron complex. In a stepwise fashion, via a dissociative mechanism, two carbonyl ligands are displaced by the diene system. However, thermal dissociation of the first CO ligand requires rather harsh conditions (ca. 140 °C). For acyclic 1,3-dienes, the diene ligand adopts an s-cis conformation to form stable q4-complexes (Scheme 1.18). 

In 1971 we succeeded, again for the first time, in transferring a carbene ligand from one metal atom to another (26, 47). For example, if one irradiates a solution of cyclopentadienyl(carbonyl) [methoxy (phenyl) carbene]-nitrosylmolybdenum(O) in the presence of an excess of pentacarbonyliron, one obtains tetracarbonyl[methoxy (phenyl) carbene]iron(0) with the simultaneous formation of cyclopentadienyl (dicarbonyl) nitrosylmolyb-denum ... 

A new class of boron compounds has been prepared by the reaction of pentacarbonyliron with dichloro(dimethylamino)borane to form (CO)4FeBN(CH3)2, a borylene complex.10 The mono- and dihaloamino-boranes can be prepared from the corresponding tris(amino)borane.11,12 Pyrolysis of the tris(primary amino)borane B(NHR)3 yields the borazine B3(NHR)3N3R3.3... 

Treatment of the alkenylpotassium (210 X = K) with dimethoxyfluoroborane and peroxide gives (+)-myrtenoI (210 X = OH) contaminated with 2% of trans-pinocarveol (213 R = H).331 Alkylation of the ir-allyl complex (230) occurs directly on carbon from the more hindered side of the molecule to yield (231).332 Heating a-or /3-pinene with pentacarbonyliron yields the chiral ring skeletal enantiomers (232) and (233) by 7r-allyl cyclobutane ring-expansion.333... 

The cationic manganese carbonyl derivative Mn(CO)4(phen)+ has been isolated as the Co(CO)4 and Mn(CO)5 salts (445) and the technetium derivatives Tc(CO)s(phen)X are also known. The color is a function of the halogen X, changing from colorless (X = Cl), through bright brown (X = Br), to brown (X = I) (374). The reaction of bipyridyl with pentacarbonyliron induces disproportionation (375) this can also occur when bis(l,3-cyclohexadiene)tetracarbonyldicobalt is the reactant. However, [L2(CO)4Co2] has been prepared 62). 

The stereochemistry of the reaction has been studied in rigid and in nonrigid systems. A new route to functionalized 1,2-dioxetanes has been described. Lactones can be obtained by oxidation of the intermediate complex formed from dienemonooxiranes by carbonyl group insertion with pentacarbonyliron (Eq. 188). ... 

According to ref. 3, nonacarbonyldiiron [Fe2(CO)g] was synthesized by photochemical dimerization of pentacarbonyliron [Fe(CO)s] in a mixture of glacial acetic acid and acetic acid anhydride (10 1) at room temperature employing a Dema irradiation apparatus with a Philips HPK 125 W or TQ 150 W medium pressure mercury lamp. The material should be stored at -25°C in a freezer and handled under an atmosphere of argon. Pentacarbonyliron [Fe(CO)s] was a gift from BASF AG, Germany and was used without further purification. 

Various kinds of olefin isomerizations are effectively promoted by Fe(CO)5. However, because the isomerized product is usually released from the iron complex by oxidation, these isomerizations require a stoichiometric amount of pentacarbonyliron as described below (Scheme 10.4, eq (1)) [16-17]. 

Pentacarbonyliron is also capable of producing lactone from epoxides [21]. The reaction of dienemonoepoxide with Fe(CO)5 gives a p-TC-allylcarbonyliron complex. Unsaturated lactone is obtained after treatment of the allyliron intermediate with cerium (Scheme 10.6). 

Photolysis of Pentacarbonyliron in Low Temperature Matrices. Pentacarbonyliron Fe(C0)j provides an adequate system for photochemical studies in low temperature matrices in view of its role in catalytic and photochemical reactions and its simple structure. The formation of Fe(C0)j fragments (n=l-4) was reported based on the IR spectra of the UV photolysis products of matrix-isolated Fe(C0)j (18). We first measured the MBssbauer spectra of unstable species such as Fe(C0)2, Fe(CO)3, Fe(CO)4, Fe2(C0)g arising from the photolysis of Fe(C0)5 isolated in a... 

Photochemical Reactions of Pentacarbonyliron with Ethene Cocondensed in Low Temperature Matrices. We have also studied the photochemical reactions of pentacarbonyliron with ethene cocondensed in the nitrogen matrix (22). While the formation of Fe(CO) (C2H ) in UV photolysis of Fe(C0)5 cocondensed with C2H in argon matrix was inferred from the IR spectra (23), no MWssbauer parameters were reported on this relatively unstable product. In order to elucidate the detailed mechanisms of photochemical reactions with cocondensed species, we have compared the products from the homogeneous cocondensed matrix with those from the stratified matrix where Fe(C0)j and C2H constituted separate... 

The removal of halogen with intermolecular formation of a new carbon-carbon double bond may be regarded as an extension of the Wurtz-Fittig reaction it has been applied almost exclusively to the preparation of hydrocarbons but its importance is mainly in the stilbene series. Buckles and Matlack870 prepared tetraphenylethylene in 70% yield by treating diphenylmethylene dibromide with copper powder and tetrakis-(p-nitrophenyl)ethylene has been obtained in 47% yield from bis-(p-nitrophenyl)methylene dibromide by means of pentacarbonyliron.8 71... 

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