Carbonyl complexes of iron

Carbohalogenation of various terminal or internal alkynes, via addition of perfluoroalkyl iodides or bomides, is catalyzed by carbonyl complexes of iron, cobalt or ruthenium. In this case, dichlorotris(triphenylphosphane)ruthenium(II) is not active as a catalyst. rram-Addition products are usually obtained in good yield under mild reaction conditions36. 

R. Salzmann, C.J. Ziegler, N. Godbout, M.T. McMahon, K.S. Sushck, E. Oldfield, Carbonyl complexes of iron(ii), tuthenium(ii), and osminm(ii) 5,10,15,20-tetraphenylporphyrinates a comparative investigation by X-ray crystallography, sohd-state NMR spectroscopy, and density functional theory, J. Am. Chem. Soc. 

Anionic carbonyl complexes of iron, ruthenium, chromium, molybdenum, tungsten, etc., also react with 3,4-dichlorocyclobutene or its derivatives. In order to obtain anionic derivatives, metal carbonyls are reduced by means of sodium amalgam [equations (8.29H8.31)]. 

Recording the mass of the moleeular ion as accurately as possible can be invaluable in proving the identity of a compound. Consider a carbonyl complex of iron that gives a molecular ion at 504 Da. As iron has a mass of 56 Da, that total mass can be fitted equally well by the formulae [Fe(CO)ie] (admittedly somewhat unlikely ), [Fe2(CO)i4], [Fe3(CO)i2], [Fe4(CO)io], [Fe5(CO)g] and so on. But with high-resolution instruments it is possible to determine the masses of ions to within 0.0001 Da, and as atomic masses are not exact integers, it is usually possible to distinguish between the various options. In our iron carbonyl example, the exact masses are 503.85366,503.79876,503.74386,503.68896, and 503.63406 Da, respectively, so it is easy to decide which formula is correct. It is always a good idea to measure the mass of the parent ion in a spectrum accurately, to check that the proposed formula is correct. 

In the early work on the thermolysis of metal complexes for the synthesis of metal nanoparticles, the precursor carbonyl complex of transition metals, e.g., Co2(CO)8, in organic solvent functions as a metal source of nanoparticles and thermally decomposes in the presence of various polymers to afford polymer-protected metal nanoparticles under relatively mild conditions [1-3]. Particle sizes depend on the kind of polymers, ranging from 5 to >100 nm. The particle size distribution sometimes became wide. Other cobalt, iron [4], nickel [5], rhodium, iridium, rutheniuim, osmium, palladium, and platinum nanoparticles stabilized by polymers have been prepared by similar thermolysis procedures. Besides carbonyl complexes, palladium acetate, palladium acetylacetonate, and platinum acetylac-etonate were also used as a precursor complex in organic solvents like methyl-wo-butylketone [6-9]. These results proposed facile preparative method of metal nanoparticles. However, it may be considered that the size-regulated preparation of metal nanoparticles by thermolysis procedure should be conducted under the limited condition. 

Anionic complexes of iron and cobalt rapidly react with permethylated a,a>-dihalopolysilanes to give disubstituted polysilanes [1,2]. Because of the low nucleophilicity of pure carbonyl-cobaltate, we substituted one of the CO ligands with PPh3, whereupon the reactivity increased dramatically. 

TABLE 12. Reduction potentials of porphyrin-iron carbonyl complexes of germanium and tin in CH2CI2 with TBA(PF<5), 0.1 M, on Au electrodes vs SCEa... 

Structural models, which are synthesized to imitate features of the proposed structure of the active site. These may be used to demonstrate the chemical conditions, which allow such structures to exist, to investigate their chemical properties and to give a better understanding of the spectroscopic characteristics of the native proteins. Examples of these include the mixed carbonyl/cyano complexes of iron, used to verify the infrared spectra to the hydrogenases (Fig 7.4) (Lai et al. 1998) and the nickel-thiolate complexes which have low redox potentials like the hydrogenases (Franolic et al. 1992). 

Nonconjugated dienes are rearranged to iron carbonyl complexes of conjugated dienes when treated with FefCOjs or Fe3(CO)i2. Thus 1,4-pentadiene gives tmw -l,3-pentadieneiron tricarbonyl (34) possibly by the route ... 

These expressions have been applied to the series isocyanide and carbonyl complexes of rhenium(I) tr ns-[ReL2(dppe)2]" (L = CNR, CO) [19, 20] and of nitrile and carbonyl compounds of iron(II) tmns-[FeL2(depe)2]2+ (L = NCR, CO) [35], and the Es and /J values of the corresponding trons- ReL(dppe)2 " and trans- FeL(depe)2 " " centers, which are given in Table 9, have been discussed earlier. 

It has been claimed that attempts to prepare iron and nickel carbonyl complexes of 1,2-and 1,4-dihydropyridines resulted in reduction of the metal (67AG(E)988). This problem has been avoided by using dihydropyridines with electron withdrawing groups on the nitrogen... 

Olefins readily displace CO groups from the iron carbonyls, Fe(CO)5, Fe2(CO)9, and Fe3(CO)12, to form complexes in which a C C bond of the olefin takes the place of each displaced CO group, and by donating its ir-electrons preserves the formal inert gas electron configuration of the iron atom in the complex. Acrylonitrile is the only reported example of a monoolefin complexing with iron in this way, but many complexes of iron with polyolefins are known. 

Fig. 15.2 Structures of the simple carbonyl complexes of chromium, iron, and nickd.

As alluded to earlier, we have amassed a large body of X-ray data for binuclear iron carbonyl complexes of the Fe2(CO)6(X)(PPh2) type where X represents a three-electron donor ligand. The P-31 chemical shifts for these compounds are tabulated with Fe-P-Fe angles in Table III and a plot of 8 vs. angle is shown in Figure 11. Although the correlation is by no means perfect there is an unmistakable increase in... 

Gibson nde Thomas, and Tustin have reported the formation of a number of iron carbonyl complexes of a,/J-unsaturated acyl silanes226. Propenoyl trimethylsilane did not give a stable complex, but the iron tricarbonyl complexes of cinnamoyl silanes were very stable. 

In this case (compare with Ref. 268), the Te — Te bond remains. This bond is not destroyed also under interaction of diphenylditellurides with cyclopentadienyl-carbonyl complexes of manganese (3.99a) [272] and iron (3.99b) [273] ... 

The mass spectra of some binuclear iron carbonyl complexes of the type (triene) Fe2(CO)g have been investigated 26>33b Reaction between... 

The mass spectra of binuclear iron carbonyl complexes of acenaphthylene and azulene have been briefly reported 26). The acenaphthylene complex previously 43> reported as Ci2H8Fe2(CO)6 exhibits Ci2H8Fe2 (CO)5 as the highest m/e ion the implied pentacarbonyl formulation was later 44> confirmed by X-ray crystallography which indicated structure 16. The reaction between azulene and Fe(CO)s has been reported 45> to give dark red CioHgFegfCOJs this formulation was confirmed by... 

In contrast to the chalcogen-bridged complexes, no similar oxygen-bridged compounds of iron, cobalt, or nickel exist. However, we obtained such oxo or i-ol-carbonyl complexes of chromium and its homologs, as well as of rhenium. The compounds are the products of the reactions of the respective metal carbonyls with bases (VII). 

Compounds Derived from Alkynes and Carbonyl Complexes of Cobalt, 12, 323 Conjugate Addition of Grignard Reagents to Aromatic Systems, 1, 221 Coordination of Unsaturated Molecules to Transition Metals, 14, 33 Cyclobutadiene Metal Complexes, 4, 95 Cyclopentadienyl Metal Compounds, 2, 365 Diene-Iron Carbonyl Complexes, 1,1... 

Tn transition Group Villa, complexes of iron, cobalt, nickel and rhodium are active in CO3 dcoxygenation. The reactivity of a series of metal carbonyl anions with carbon dioxide has been found to parallel their relative nucleophilicities. The highly nucleophilic (CpFefCO) ] reacts to form the dimer [CpFefCO) ] 2 and carbonate, whereas (CofCO) ]" is unrcactivc [284]. 

Transition metal derivatives are known to stabilize unusual molecules in their coordination sphere. First studies on silanediyl- and silyl complexes of iron carbonyls have been carried out [7-9],... 

Carbonyl derivatives of iron(II) exist. Pentacarbonyl-iron(O) is oxidized by halogens to give carbonyl halide complexes (equation 35). The stability of these compounds with respect to thermal decomposition and hydrolysis increases in the sequence Cl < Br < I. 

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