- Manganese- and rhodium-catalyzed phenylsilane hydrosilation-deoxygenation of iron acyl complexes Cp(L)(CO)FeC(O)R (L = CO, PPh3, P(OMe)3, P(OPh)3; R = CH3, Ph, CHMe2, CMe3)
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The manganese carbonyl acyl complexes L(CO)4MnC(O)R (L = CO, R = CH3 (2a); L = CO, R = Ph (2b); L = PPh3, R = CH3 (2c)) are precatalysts for the PhSiH3 hydrosilation-deoxygenation of Cp(CO)2FeC(O)CH3 (1a) to Cp(CO)2FeCH2CH3 (6a). Thus, 2a (4%) and 1.1 equiv of PhSiH3 reduce 1a initially to a mixture of [Cp(CO)2FeCH(CH3)O]3-xHxSiPh (x = 2 (3b), 1 (4b), and 0 (5b)) (7-8 h), which transforms to a mixture of 5b (62%) and 6a (35%) (12 h). Similarly, 2b and PhSiH3 transform 1a to a mixture containing 4% 3b, 22% 4b, 72% 5b, and 2% 6a (30 min), then up to 15-20% 6a (12 h). Use of 2c as the precatalyst selectively yields 71% 4b and 10% 6a (30 min), then up to 19% 6a (5 h). Both 4b and 5b were isolated by size-exclusion chromatography and characterized as mixtures of four stereoisomers, 4b as a pair of enantiomers having a prochiral center and two meso diastereoisomers with pseudoasymmetric centers and 5b as a diastereomeric pair of enantiomers. The PhSiH3 (1.6 equiv)/RhCl(PPh3)3 (3%) system conveniently transforms Cp-(L)(CO)FeC(O)R to their alkyl derivatives Cp(L)(CO)FeCH2R. Seven iron acyl complexes were studied (Cp(CO)2FeC(O)R, R = Me, Ph, iPr, tBu; Cp(L)(CO)FeC(O)CH3, L = PPh3, P(OMe)3, and P(OPh)3), which gave 49-87% isolated yields of Cp(L)(CO)FeCH2R. Their modest yields correspond to the presence of byproducts, Cp(CO)2FeCH=CH2 (32%) and 4b (14%) with 1a and 10-15% of the vinyl complexes with L = PPh3 and P(OPh)3.
- Mao, Zhibiao,Gregg, Brian T.,Cutler, Alan R.
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- Carbon Dioxide Activation as an η1-C Metallocarboxylate: Metallocarboxylate Ester Derivatives as a C1 Template in Co-ordinated Ligand Reactions
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In tetrahydrofuran the reaction between Fp2Mg and CO2 gives the symmetrical metallocarboxylate (FpCO2)2Mg, which can be alkylated to give the ester FpCO2Me; its activated ester FpC(OMe)2+ serves as a C1 template for reduction to FpCH2OMe.
- Forschner, Thomas,Menard, Kevin,Cutler, Alan
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Read Online
- Photoactivated silicon-oxygen and silicon-nitrogen heterodehydrocoupling with a commercially available iron compound
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Silicon-oxygen and silicon-nitrogen heterodehydrocoupling catalyzed by the commercially available cyclopentadienyl dicarbonyl iron dimer [CpFe(CO)2]2 (1) under photochemical conditions is reported. Reactions between alcohols and PhSi
- Cibuzar, Michael P.,Hammerton, James,Reuter, Matthew B.,Waterman, Rory
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supporting information
p. 2972 - 2978
(2020/03/13)
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- Visible Light Photocatalysis Using a Commercially Available Iron Compound
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[CpFe(CO)2]2 (1) (Cp = η5-C5H5) is an effective precatalyst for the hydrophosphination of alkenes with Ph2PH under visible light irradiation, which appears to be a unique way to promote metal-catalyzed hydrophosphination. Additionally, 1 is a photocatalyst for the dehydrogenation of amine boranes and formation of siloxanes from tertiary silanes. These reactions have similar, if not improved, reactivity over the same transformations using 1 or related CpFeMe(CO)2 under UV irradiation, consistent with the notion that hydrophosphination with 1 proceeds via formation of CpFe(CO)2?. These results demonstrate that catalyst selection can avail the use of commercially available LED bulbs as photon sources, potentially replacing mercury arc lamps or other energy intensive processes in known or new catalytic reactions.
- Pagano, Justin K.,Bange, Christine A.,Farmiloe, Sarah E.,Waterman, Rory
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p. 3891 - 3895
(2017/10/30)
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- Characterization of the μ-(η1-C: Η2-S,S′) dithiocarboxylate complexes Cp(CO)2Fe-CS2-Zr(X)Cp2 (X=Cl, OCMe3); CS2 insertion into the FeZr bond of the heterobimetallic complex Cp(CO)2Fe-Zr(OCMe3)Cp2
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Treatment of the carbon disulfide adducts FpCS2K and Fp′CS2K [Fp′=(η5-C5H4CH 3)Fe(CO)2] with Cp2ZrCl2 affords the μ-(η1-C: η2-S,S′) dithiocarboxylate complexes FpCS2ZrClCp2 (1) and Fp′CS2ZrClCp2 (2). Both stable products were fully characterized. Metathesis between FpCS2K and Cp2ZrCl(OCMe3) provided FpCS2Zr(OCMe3)Cp2 (3), which was not obtained analytically pure. This product was characterized by comparison of its IR and 1H-, 13C{1H}-NMR spectral data with that for 1 and 2. The iron-zirconium complex FpZr(OCMe3)Cp2 (4) was transformed by one equivalent of CS2 to 3 (75% spectroscopic yield), a reaction that did not occur for FpZrClCp2. An insertion pathway is discussed for incorporating the CS2 into the Fe-Zr bond of FpZr(OCMe3)Cp2.
- Pinkes, John R.,Tetrick, Stephen M.,Landrum, Bruce E.,Cutler, Alan R.
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- Formation and chemistry of the transient 17-electron compounds CpFe(CO)L· (L = PMe2Ph, PPh3)
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Hydride hydrogen atom abstraction from the 18-electron compounds CpFe(CO)LH (L = PMe2Ph, PPh3) by the trityl radical results in formation of the 17-electron species CpFe(CO)(PMe2Ph)· and (CpFe(CO)PPh3
- Kuksis, Inga,Baird, Micheal C.
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p. 137 - 143
(2007/10/03)
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- Metallocarboxylate trialkylsilyl esters: A means of derivatizing the carbon dioxide containing η1-C metallocarboxylates Cp(CO)2FeCO2-Li+ and Cp(CO)2FeCO2-Na+
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The metallocarboxylates FpCO2- (6·Li+,Na+) are prepared by treating the requisite Fp- metalate Li+ or Na+ [Fp = Cp(CO)2Fe] with 1.5 equiv of CO2 in THF (-80°C). These unstable η1-C CO2 adducts, characterized by IR and 13C NMR spectroscopy for 6·Li+, react with methyl iodide or with methyl triflate to give FpCH3 exclusively. This reaction course is consistent with CH3I selectively reacting with Fp-, thus driving an otherwise disfavored dissociative equilibrium: 6 ? Fp- + CO2. Trimethylsilyl chloride and tert-butyldimethylsilyl chloride both intercept 6·Li+ or 6·Na+ and give the corresponding metallocarboxylate trialkylsilyl ester. FpCO2Si(CH3)3 is unstable at room temperature [decomposing to Fp2, not to the stable FpSi(CH3)3], and FpCO2Si(CH3)2[C(CH3)3] is isolated as a stable, analytically pure yellow-brown gum (85% IR spectral yield, 53% isolated). No evidence for silylating Fp- was found. Use of hard oxophilic trialkylsilyl chlorides thus affords derivatives of the metallocarboxylate ligand on FpCO2- (6·Li+,Na+).
- Giuseppetti, Mary E.,Cutler, Alan R.
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p. 970 - 973
(2008/10/08)
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- Hydride Addition Reactions of the Olefin Complexes 5-C5H5)(CO)2(Olefin)>; Formyl Formation as the Kinetically Preferred Process; Regio- and Stereo-selectivity during Addition to the Co-ordinated Olefins
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Reactions of the complexes (1+) (cp=η5-C5H5; olefin=CH2=CH2, Ch2=CHMe, 1-hexene, or methylenecyclohexane) with hydride donors under a variety of conditions normally yield the alkyl products of hydride addition to the olefin, and the hydride , a product which has not been previously noted.Detailed examination of the addition reactions of the complexes of CH2=CHMe, 1-hexene, and methylenecyclohexane show that the reactions exhibit the no recognizable patterns of regioselectivity, in contrast to many other metal-olefin systems.Addition of deuteride to (1+) (C6H10=cyclohexene) gives only the trans isomer of the 2-deuteriocyclohexyl complex, consistent with exo attack by the nucleophile on the co-ordinated olefin.Reaction of (1+) with NaBH4 in acetone at low temperature gives an unstable formyl compound, presumably , as the kinetic product.On warming, the formyl compound converts smoothly to the above-mentioned hydride complex rather than to the corresponding ethyl complex.The mechanistic implications of these results are discussed.
- Cameron, Alan D.,Laycock, David E.,Smith, Vedene H. jun.,Baird, Michael C.
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p. 2857 - 2862
(2007/10/02)
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- Transition organometallic mediated synthesis of a malonic ester from carbon monoxide
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Coordinated ligand reactions using the Fp = (η-C5H5)(CO)2Fe system as a template for converting three CO groups into the C3 skeleton of dimethyl malonate, CH2(CO2Me)2, are reported. The first CO originates in the previously reported reduction of FpCO+ to FpCH2OMe, which is the precursor to Fp=CH2+. Carbonylation of Fp=CH2+, followed by methanolysis, incorporates the second CO (which was exogenous, not ligated) as the ester carbonyl on the carbomethoxymethyl complex FpCH2CO2Me (2a). Oxidation-promoted carbomethoxylation of 2a (using Ce(IV) in methanol) then releases the free malonic ester - the third CO arriving via oxidation-induced alkyl-CO migratory insertion on 2a. Attempts at independently synthesizing FpCOCH2CO2CH2CH3 by acylating Fp1- with ethyl malonyl chloride are also reported.
- Bodnar,Crawford,Cutler
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p. 947 - 950
(2008/10/08)
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- Synthesis and Reactivity of Silicon Transition Metal Complexes, XIV. Reaction of Cp(CO)2Fe-Substituted Silanes with Dicobaltoctacarbonyl: Synthesis of Silicon Compounds with Two, Three and Four Transition Metal Ligands
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The reaction of Cp(CO)2Fe-SiHCl2 with Co2(CO)8 yields the heteronuclear complex Cp(CO)2Fe-SiCl2-Co(CO)4 (1) and HCo(CO)4. 1 is degradated by AgBF4 to Cp(CO)2Fe-SiF3.PMe3 transforms 1 to Cp(CO)2Fe-SiCl2-Co(CO)3PMe3 (2).LnM-SiH2Me reacts with Co2(CO)8 to give LnM-SiMe-Co2(CO)7 .Starting with Cp(CO)2Fe-SiH3, μ3-Cp(CO)2Fe-SiCo3(CO)9 (4), the second example of a μ3-metallosilylidine tricobalt cluster is obtained in high yield, which is cleaved by acetic acid to Cp(CO)2Fe-Si3 (5).The composition and structure of the silicon transition metal complexes 1-5 is proved by NMR, IR and mass-spectroscopy. 29Si NMR shifts are determined for the first time for tri- and tetra-metalated silicon species. - Key words: Metalation of Silicon Hydrides, Silicon Transition Metal Complexes, Heteronuclear Cluster Compounds
- Malisch, Wolfgang,Wekel, Hans-Ulrich,Grob, Irmgard,Koehler, Frank H.
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p. 601 - 609
(2007/10/02)
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