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  • 1
    Electronic Resource
    Electronic Resource
    The Reduction of [Fe(CO)2L2X2] (L = P(OMe)3, P(OiPr)3, PEt3; X = Br, I) - From Iron(II) to Iron(0) via Stable Iron(I) Intermediates (1995)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 1 (1995), S. 541-548 
    Details
    ISSN: 0947-6539
    Keywords: dinitrogen complexes ; EPR spectroscopy ; iron compounds ; reductions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reduction of [Fe(CO)2-L2X2] (L = P(OMe)3 X = Br (1a), I (1b); L = P(OiPr)3, X = Br (2a), I (2b); L = PEt3, X = Br (3a), I (3b)) with Zn in dioxane (1a,b-2a,b) or PhLi in ether (3a,b) led to formation of the corresponding dicarbonyl(halo)bis(phosphorus donor)iron(I) complexes (L = P(OMe)3, X = Br (4a), I (4b); L = P(OiPr)3, X = Br (5a), I (5b); L = PEt3, X = Br (6a), I (6b)). Slightly contaminated 5a,b and pure 6a,b were isolated as stable crystalline blue or blue-green complexes. Complexes 4a,b were obtained, with only minor impurities, by comproportionation of 1a,b and the dicarbonyl(halo)bis-(trimethylphosphite)ferrate anions 7a,b and characterized in THF solution. The comproportionation products 5a,b-6a,b were obtained in high yields by reaction of 2a,b-3a,b with the dinitrogen complexes 13-15. Further reduction of 4a,b-6a,b or exhaustive reduction of 1a,b-3a,b with sodium amalgam or iBuLi in THF afforded the nonisolable dicarbonyl-(halo)bis(phosphorus donor)ferrate(o) anions (7a,b-9a,b). The latter were characterized by acidification with trifluoroacetic acid or acetic acid yielding stable dicarbonyl (halo) hydridobis (phosphorus donor)iron(II) complexes (L = P(OMe)3, X = Br (10a), I (10b); L = P(OiPr)3, X = Br (11a), I (11b);L = PEt3, X = Br (12a), I (12b)). In the presence of N2, 8a was transformed into dinitrogen complex [Fe(CO)2{P(OiPr)3}2N2] (13). With 9a,b the reaction led to formation of [Fe-(CO)2(PEt3)2)2N2] (14) and [{Fe(CO)2-(PEt3)2}2(μ-N2)] (15). In solution at low temperature (-90 to 0°C), the dinitrogen complexes 14 and 15 are in equilibrium with each other. Complexes 13, 14, and 15 were characterized by IR, 1H, 13C, 31P, and 15N NMR spectroscopy. The structures of 5a, 6b, 14, and 15 were determined by X-ray diffraction studies.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19950010808
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  • 2
    Electronic Resource
    Electronic Resource
    Acetylene/Vinylidene Rearrangements of Fe(CO)2L2(silylacetylene) Complexes (L=Phosphorus Donor) (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 183-194 
    Details
    ISSN: 0009-2940
    Keywords: Iron ; Alkyne complexes ; Vinylidene complexes ; C-H oxidative addition ; Rearrangements ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of a mixture of Fe(CO)2(PEt3)2N2 (1a) and [Fe-(CO)2(PEt3)2]2N2 (1b) with acetylene leads to three complexes: Fe(CO)2(PEt3)2(π-HC≡CH) (2a), Fe(CO)2(PEt3)2(H)(C≡CH) (2b), and Fe(CO)2(PEt3)2=C=CH2 (2c). Upon chromatography on silylated silica gel the mixture of 2a-c is completely transformed into 2c. The analogous reaction of 1a, b or of Fe(CO)2[P(OiPr)3]2N2 (1d) with HC≡CSiMe3 affords the primary oxidative addition products Fe(CO)2L2(H)(C≡CSiMe3) [L = PEt3, 3a; L = P(OiPr)3, 3c]. The presence of a small amount of Al2O3 in hexane irreversibly converts 3a and 3c into the vinylidene compounds Fe(CO)2L2=C=C(H)SiMe3[L = PEt3, 4a; L = P(OiPr)3, 4c]. The chromatographic work-up of 4c additionally leads to the hydrolysis product Fe(CO)2[P(OiPr3)2]2=C=CH2 (2d). The reaction of the phosphite-substituted derivative Fe(CO)2[P(OMe)3]2I- (1c) with silylacetylene allows detection of the acetylene species Fe(CO)2 [ P(OMe)3]2 (HC ≡CSiMe3) (3b), as well as the acetylido hydrido derivative Fe(CO)2[P(OMe)3]2(H)(C=CSiMe3) (4b). In a slow subsequent process, or with promotion by Al2O3 in hexane, the vinylidene compound Fe(CO)2[P(OMe)3]2=C=C(H)SiMe3 is formed. 3b or 4b are hydrolyzed to Fe(CO)2[P(OMe)3]2=C=CH2 (5c) in the presence of SiO2. The reaction of disilylacetylene with 1a-d results in the formation of disilylvinylidene complexes Fe(CO)2L2=C=C(SiMe3)2 (L = PMe3, 7a; L=PEt3, 7b; L = PiPr3, 7c). An intermediate acetylene derivative could be isolated for L = PEt3 (6a) and spectroscopically detected for L = P(OMe)3 (6b), but could not be traced for L = P(OiPr)3. Further studies were devoted to the reactions of silyl diynes (Me3SiC≡CR, R = C≡CSiMe3, p-C6H4-C-CSiMe3) with 1a-c. In all cases the acetylene compounds Fe(CO)2L2(Me3-SiC≡CR) [L = PEt3, R = C≡CSiMe3, 8a; R = p-C6H4-C≡CSiMe3, 9a; L = P(OMe)3 R = CSiMe3, 8b; R = p-C6H4-C≡CSiMe3, 9b] were isolated, but only for 8b was an equilibrium process observed to form the corresponding vinylidene derivative Fe(CO)2[P(OMe)3]2=C=C(SiMe3)C-C-SiMe3 (10b). 10b hydrolyzes upon chromatography on silica gel to give Fe(CO)2[P(OMe)3]2=C=CH-C≡CSiMe3 (11b): Finally, the reaction of p-diethynylbenzene with 1a-c was explored. The acetylido hydrido species Fe(CO)2L2(H)C≡C-p-C6H4-C≡CH was isolated in the case of L = PEt3 (12a) and spectroscopically detected for L = P(OMe)3 (12b). 12b and 12a transform spontaneously and in the presence of Al2O3 in hexane, respectively, to the vinylidene complexes Fe(CO)2L2=C=C(H)R [R = C6H4-C≡CH, L = PEt3, 13a; L = P(OMe)3, 13b]. 6a, 7a, and 8a have been characterized by single-crystal X-ray diffraction studies.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300208
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