Iron complexes carbonyl phosphines

Ohst and Kochi (1986) traced changes in the electron structure that takes place during the substitution of the triethyl phosphine ligand for the carbonyl ligand in the iron-phenylphosphine-carbonyl complex (see Scheme 1.28). 

Some iron and nickel cyanide and carbonyl complexes have been reported as models of the [FeNi]-hydrogenase enzymes. The preparation and structures of the trigonal bipyramidal nickel and iron complexes with the tetradentate ligands tris(2-phenylthiol)phosphine (PS3) and tris(3-phenyl-2-thiophenyl)phosphine (PS3 ) have been reported [70, 71]. The nickel carbonyl complex [Ni(PS3 )(CO)] exhibits vco at 2029 cm compared with the value of 1940 em" for the iron earbonyl complex [Fe(PS3 )(CO)]. Both of these complexes lose CO upon oxidation. The use of cyanide in place of carbon monoxide allows for the preparation of both [Fe (PS3)(CN)] and [Fe (PS3 )(CN)] eomplexes. The IR properties of... 

Bis(phosphine) derivatives of pentacarbonyliron are starting materials for the synthesis of several organometallic iron complexes. " Iron carbonyl phosphine complexes have attracted attention because of their relevance to photochemical catalysis of olefin hydrosilation. Though Fe(CO)3(PR3)2 complexes are used widely in organotransition metal chemistry, an efficient preparation of these compounds has not been reported. Clifford and Mukherjee describe two methods for the synthesis of tricarbonyl-bis(triphenyphosphine)iron(0). They report that direct reaction between Fe3(CO)j2 and triphenylphosphine in THF solvent gives a mixture of Fe(CO)3[P(C6Hs)3]2 (27%) and Fe(CO)4[P(C5H5)3] (34%). The second... 

Among the complexes which may function in this way are pentacyano-cobaltate ion, iron pentacarbonyl, the platinum-tin complex, and iridium and rhodium carbonyl phosphines. It has been suggested that with tristriphenylphosphine Rh(I) chloride, a dihydride is formed and that concerted addition of the two hydrogen atoms to the coordinated olefin occurs (16). There are few examples of the homogeneous reduction of other functional groups besides C=C, C=C, and C=C—C=C penta-cyanocobaltate incidentally is specific in reducing diolefins to monoolefins. 

Fig. 12.2 (a) Line drawing of an acetyl(carbonyl)(cyclopentadienyl)(phosphine)iron complex, (b) Stereoview of the same molecule. [From Korp, J. D. Bernal, I. J. Organomet. Chem. 1981, 220, 355-364. Reproduced with permission.)... 

S. Davies has used an iron complex as an auxiliary for the asymmetric cyclopro-panation of a,P-unsaturated carbonyls [105]. The iron acyl is most stable in the s-cis conformation, as illustrated in Scheme 6.27, in order to avoid severe interactions between the iron ligands and R. Coordination of the Simmons-Smith reagent to the carbonyl oxygen, anti to the iron, forces the alkene moiety out of conjugation and approximately orthogonal to the carbonyl. Because of the bulky triphenyl phosphine in the rear, this rotation can only be towards the front. Transfer of the methylene via the illustrated transition state accounts for the observed diastereoselectivity. Oxidation with bromine removes the iron acyl and derivatization with a-methyl-benzyl amine allowed evaluation of the stereoselectivity. 

Bis(phosphine) derivatives of pentacarbonyliron are starting materials for the synthesis of several organometallic iron complexes.Iron carbonyl phosphine complexes have attracted attention because of their relevance to... 

Fifth, the rate of carbonyl insertion as a function of the metal center usually follows the trend 3d > 4d > 5d when the complexes are isostructural. Alkyl complexes of the first-row metals are almost always more reactive than the analogs of the third row, and they are usually more reactive than the analogs of the second row. For example, CpRu(CO)jMe requires higher temperatures to insert CO in the presence of added phosphine than does the analogous iron complex, and the osmium analogue fails to react. Similar trends have been observed for other alkyl complexes of metal-carbonyl fragments. For CpM(CO)jR complexes, the relative rates of insertion are M = Cr and Mo > W, and for RM(CO)j, the relative rates are M = Mn >... 

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