Carbonyl Complexes Fe CO

The data compiled in Table 7.5 show that the relative energies of the axial and equatorial isomers yielded by the B3LYP/II level of theory are very similar to their CCSD(T) counterparts. The B3LYP/II BDEs are always larger than the CCSD(T)/II results, but the trends predicted by the two methods for different ligands are the same. It is worth noting 

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The iron carbonyl complex [Fe(CO)5] in basic media hydrogenated steroidal dienes selectively (equations 10-12)30. 

Antimony trichloride also behaves as a Lewis base. However, sucb reactions are very limited. They include the formation of carbonyl complexes Fe(CO)3(SbCl3)2 and Ni(CO)3SbCl3. 

In 1993, Murai s group examined the effectiveness of the iron-triad carbonyl complexes Fe(CO)5, Fe2(CO)9 and Fe3(CO)12 as catalysts for the reaction of styrene with triethylsilane [47]. Whereas Fe(CO)5 showed no catalytic activity, Fe2(CO)9 and Fe3(CO)12 formed selectively P-silylstyrene 57a and ethylbenzene 58. Interestingly, Fe3(CO)12 is the catalyst that exhibited the highest selectivity. This trinuclear iron carbonyl catalyst was also successfully applied in the reaction of different para-substituted styrenes with Et3SiH giving only the (E)-P-triethylstyrenes in 66-70% yield (Scheme 4.23). 

Tris(amido)phosphines 40-43 react with Fc2(CO)9 to give mononuclear iron carbonyl complexes Fe(CO)4(PR3). IR data collected from these complexes, combined with data from similar complexes, revealed the TT-acidity of the phosphines to be 41 w 40 > 43 > P(OPh>3 >42 > PPh3 > P(NMe2)3- Variable-temperature NMR on the Fe(GO)4 complexes of 41-43 showed rapid exchange of axial and equatorial carbonyls from —80 to 20 °C, while complex 40 showed slow axial-equatorial carbonyl exchange even at room temperature, attributed to the steric bulk and rigidity of the ligand. 

Iron carbonyl complexes containing 77 -alkyl-77 -allyl coordinated hydrocarbon ligands are obtained in several ways. Nucleophilic addition to cationic iron complexes containing 77 -pentadienyl ligands yields (pentenediyl)iron complexes. Oxidatively-induced reductive elimination of these complexes can be utilized as a means to generate 1,2,3-trisubstituted cyclopropanes.The reaction of cationic cycloheptadienyl complexes (Scheme 22) with appropriate nucleophiles also yields the alkyl-allyliron carbonyl complexes. Fe(CO)s also reacts with a- or /3-pincnc in refluxing dioxane (Scheme 22) to produce an alkyl-allyliron complex. Recently, 1,2- and 1,4-disubstituted [(pentadienyl)Fe(CO)3] cations were shown to react with carbon nucleophiles, such as sodium dimethylmalonate, to yield 77 77 -allyl complexes as products. 

Iron(II) alkyl anions fFe(Por)R (R = Me, t-Bu) do not insert CO directly, but do upon one-electron oxidation to Fe(Por)R to give the acyl species Fe(Por)C(0)R, which can in turn be reduced to the iron(II) acyl Fe(Por)C(0)R]. This process competes with homolysis of Fe(Por)R, and the resulting iron(II) porphyrin is stabilized by formation of the carbonyl complex Fe(Por)(CO). Benzyl and phenyl iron(III) complexes do not insert CO, with the former undergoing decomposition and the latter forming a six-coordinate adduct, [Fe(Por)(Ph)(CO) upon reduction to iron(ll). The failure of Fe(Por)Ph to insert CO was attributed to the stronger Fe—C bond in the aryl complexes. The electrochemistry of the iron(lll) acyl complexes Fe(Por)C(0)R was investigated as part of this study, and showed two reversible reductions (to Fe(ll) and Fe(l) acyl complexes, formally) and one irreversible oxidation process."" ... 

A half-metallocene iron iodide carbonyl complex Fe(Cp)I(CO)2 was found to induce the living radical polymerization of methyl acrylate and f-bulyl acrylate with an iodide initiator (CH3)2C(C02Et)I and Al(Oi- Pr)3 to provide controlled molecular weights and rather low molecular weight distributions (Mw/Mn < 1.2) [79]. The living character of the polymerization was further tested with the synthesis of the PMA-fc-PS and PtBuA-fi-PS block copolymers. The procedure efficiently provided the desired block copolymers, albeit with low molecular weights. 

Reactions of PhC=CC=CPh with iron carbonyls [Fe(CO)s, Fe2(CO)9, or Fe3(CO)i2] give isomers of complexes Fe(CO)4 (diyne)2 (265), Fe2(CO)6 (diyne)2 (266), and Fe2(CO)7 (diyne)2 (267), to which structures analogous to those found for similar products obtained from C2Ph2 were ascribed all three isomers of the second complex were formed. The reactions of hexa-2,4-diyne and Fe(CO)s have been described in more detail. UV irradiation of mixtures of the two... 

The carbonyl compounds [Fe(CO)5], [Mn2(CO)iol, and [Co2(CO)g] react in the same manner and no traces of a neutral or cationic carbodiphosphorane complex can be detected. In the case of these earlier and middle carbonyls in non-polar solvents, apparently the hard nature of C(PPh3)2 comes into force upon attacking a carbonyl carbon atom and formation of the C2PPh3 ligand [122] in THF, DME, quantitatively the related salts (HC PPh3 2)[M(CO)J (M = Mn, x = 5 M = Co, X = 4) were formed upon deprotonation of the solvent [123, 124],... 

Carbonyl Halides and Hydrides. Fe2(CO) reacts with HBr or HI and Fe(CO)j with HBr under u.v. light to yield the halogeno-complexes [Fe(CO)3.X]2. Structure (16) is postulated, on the basis of the close similarity in i.r. spectra with those of [Fe(CO)3SR]2 complexes. 

Perfluoroethylene was first thought to react with iron carbonyl to give the iron(O) olefin complex [Fe(CO)3(C2F4)2] 213). It has since been shown that the product is a heterocyclic derivative of iron(II) (structure XII) 150, 214) and not a true olefin complex. 

Cyclo-octatetraene reacts with iron carbonyls to form complexes with the compositions [Fe(CO)3(C8H8)], [Fe2(CO)6(C8H8)], and [Fe2(CO)7(C8H8)] 152, 168, 180). Nakamura and Hagihara 166) report that the complex [Fe(CO)3(C8H8)] decolorizes bromine in carbon tetrachloride and shows absorption bands in its infrared spectrum at 699, 716, and 720 cm-1 due to cis-double bonds. They suggest structure (XVI) for this complex, i.e., the hydrocarbon retains its tub form in the complex. These results are con-... 

In this contribution we describe facile, high-yield syntheses of the series of zerovalent iron isocyanide complexes Fe(CO)5 (CNC6H3Me2-l,3)n ( n = 1-5). The starting material is iron pentacarbonyl, and cobalt(II) chloride is used as a catalyst to achieve the stepwise replacement of carbonyl groups by 2-isocyano-l,3-dimethylbenzene.4,9... 

Recently the unprecedented example of stereoselective C—Si bond activation in cu-silyl-substituted alkane nitriles by bare CQ+ cations has been reported by Hornung and coworkers72b. Very little is known of the gas-phase reactions of anionic metal complexes with silanes. In fact there seems to be only one such study which has been carried out by McDonald and coworkers73. In this work the reaction of the metal-carbonyl anions Fe(CO) (n = 2, 3) and Mn(CO) (n = 3, 4) with trimethylsilane and SiH have been examined. The reactions of Fe(CO)3 and Mn(CO)4 anions exclusively formed the corresponding adduct ions via an oxidative insertion into the Si—H bonds of the silanes. The 13- and 14-electron ions Fc(CO)2 and Mn(CO)3 were observed to form dehydrogenation products (CO) M(jj2 — CH2 = SiMe2) besides simple adduct formation with trimethylsilane. The reaction of these metal carbonyl anions with SiFLj afforded the dehydrogenation products (CO)2Fe(H)(SiII) and (CO)3Mn(II)(SiII). ... 

The mass spectrum of Fe2(CO)9, long assumed to be completely involatile, shows a parent ion, but the base peak is Fe2(CO) J, with a structure retaining the three bridging carbonyl groups [Fe(CO)3Fe]+ (70). Similar bridged ions containing iron have been postulated in the spectra of some phosphine and sulfide complexes (Section VI). 

I remember with great satisfaction my collaboration with J. S. Anderson in the Heidelberg Institute. In 1932 he made the volatile, previously unrecognized as such, dinitrosyldicarbonyliron by the action of pure nitric oxide on a solution of Fe3(CO)12 in iron pentacarbonyl (98). The complex Fe(CO)2(NO)2 was a deep red liquid at room temperature. With this compound the isoelectronic series Ni(CO)4, Co(CO)3NO, Fe(CO)2(NO)2 arose, and in this manner the field of carbonyl nitrosyls was opened up. The next member of this isoelectronic series, Mn(CO)(NO)3, predicted by us in 1932, was discovered recently (99). A study of the chemical behavior of the carbonyl nitrosyls, namely the ready substitution of the CO but not of the NO groups, was essentially established by Anderson (100), with the isolation of the derivatives Fe(NO)2py2, Fe(NO)2(o-phen), Co(NO)(CO)(o-phen), and Co(NO)(CO)(PR3)2, etc. 

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