- Novel synthesis of Bis (N-oxopyridine-2-thionato) zinc (II) using solid precursors
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Unprecedented solid-transchelation reaction has been established for the synthesis of zinc pyrithione nanoparticles to control particle size within sub-micron range through direct reaction between insoluble layered zinc basic salts and aqueous sodium pyrithione solution at room temperature under ambient atmosphere. The change in crystalline phases upon reaction time clearly reveals that insoluble zinc precursors transform into zinc pyrithione nanoparticles within very short reaction time. Distinguished from usual precipitation reactions, the resulting zinc pyrithione nanoparticles exhibit a narrow size distribution. This unprecedented reaction would leads to a new route for efficient preparation of zinc pyrithione nanoparticles. And it is expected that nanosized zinc pyrithione leads to a great expansion of its application fields.
- Jo, Won-young,Paek, Seung-Min,Park, Man,Hwang, Seong-Ju,Choy, Jin-Ho
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- Synthesis of Bis(trityl)iron(II) and Formation of the Iron(0)-Stabilized o, o-Isomer of Gomberg's Dimer
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Treatment of Fe(OAc)2 in THF with 2 equiv of Li(CPh3) at -25 °C results in the formation of [Fe(ν5-CPh3)2] (1) in 22% yield. Complex 1 was characterized by X-ray crystallography, NMR spectroscopy, and 57Fe M?ssbauer spectroscopy and features an ν5 binding
- Hayton, Trevor W.,Touchton, Alexander J.,Wu, Guang
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supporting information
p. 4045 - 4049
(2021/12/13)
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- Protonation and electrochemical properties of a bisphosphide diiron hexacarbonyl complex bearing amino groups on the phosphide bridge
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A bisphosphide-bridged diiron hexacarbonyl complex 3 with NEt2 groups on the phosphide bridge was synthesized to examine a new proton relay system from the NEt2 group to the bridging hydride between the two iron centers. As a precurs
- Shimamura, Takehiko,Maeno, Yuki,Kubo, Kazuyuki,Kume, Shoko,Greco, Claudio,Mizuta, Tsutomu
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p. 16595 - 16603
(2019/11/19)
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- Phosphorus-carbon bond forming reactions of iron tetracarbonyl-coordinated phosphenium ions
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Abstraction of chloride from [Fe(CO)4(PPh2Cl)] (1) in the presence of PPh3 leads to [Fe(CO)4(PPh2(PPh3))][AlCl4] (2), an iron complex of a phosphine-coordinated phosphenium ion. The PPh3 is readily displaced by ferrocene, leading to an electrophilic aromatic substitution reaction, and formation of [Fe(CO)4{PPh2Fc}] (3) (Fc = ferrocenyl). Alternately, chloride abstraction from 1 in the presence of ferrocene leads directly to 3, via a transient phosphenium ion complex. The transient phosphenium ion complex also reacts with N,N-diethylaniline, indole, and pyrrole to form the respective p-anilinyl, 3-indolyl, and 2-pyrryl phosphine complexes via electrophilic aromatic substitution. Chloride abstraction from [Fe(CO)4(PPhCl2)] in the presence of ferrocene leads to a double substitution reaction, forming [Fe(CO)4{PPhFc2}] (13).
- King, Ryan C.,Nilewar, Shrikant,Sterenberg, Brian T.
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- Iron Catalyzed Hydroformylation of Alkenes under Mild Conditions: Evidence of an Fe(II) Catalyzed Process
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Earth abundant, first row transition metals offer a cheap and sustainable alternative to the rare and precious metals. However, utilization of first row metals in catalysis requires harsh reaction conditions, suffers from limited activity, and fails to tolerate functional groups. Reported here is a highly efficient iron catalyzed hydroformylation of alkenes under mild conditions. This protocol operates at 10-30 bar syngas pressure below 100 °C, utilizes readily available ligands, and applies to an array of olefins. Thus, the iron precursor [HFe(CO)4]-[Ph3PNPPh3]+ (1) in the presence of triphenyl phosphine catalyzes the hydroformylation of 1-hexene (S2), 1-octene (S1), 1-decene (S3), 1-dodecene (S4), 1-octadecene (S5), trimethoxy(vinyl)silane (S6), trimethyl(vinyl)silane (S7), cardanol (S8), 2,3-dihydrofuran (S9), allyl malonic acid (S10), styrene (S11), 4-methylstyrene (S12), 4-iBu-styrene (S13), 4-tBu-styrene (S14), 4-methoxy styrene (S15), 4-acetoxy styrene (S16), 4-bromo styrene (S17), 4-chloro styrene (S18), 4-vinylbenzonitrile (S19), 4-vinylbenzoic acid (S20), and allyl benzene (S21) to corresponding aldehydes in good to excellent yields. Both electron donating and electron withdrawing substituents could be tolerated and excellent conversions were obtained for S11-S20. Remarkably, the addition of 1 mol % acetic acid promotes the reaction to completion within 16-24 h. Detailed mechanistic investigations revealed in situ formation of an iron-dihydride complex [H2Fe(CO)2(PPh3)2] (A) as an active catalytic species. This finding was further supported by cyclic voltammetry investigations and intermediacy of an Fe(0)-Fe(II) species was established. Combined experimental and computational investigations support the existence of an iron-dihydride as the catalyst resting state, which then follows a Fe(II) based catalytic cycle to produce aldehyde.
- Pandey, Swechchha,Raj, K. Vipin,Shinde, Dinesh R.,Vanka, Kumar,Kashyap, Varchaswal,Kurungot, Sreekumar,Vinod,Chikkali, Samir H.
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supporting information
p. 4430 - 4439
(2018/04/05)
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- Coordination chemistry and oxidative addition of trifluorovinylferrocene derivatives
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Complexes using trifluorovinylferrocene and 1,1′-bis(trifluorovinyl)ferrocene as ligands can be obtained by the reaction with a series of fragments of transition metal complexes. Formation of [Pt(η2-trifluorovinylferrocene)(PPh3)2] (1), [{Pt(PPh3)2}2(η2-1,1′-bis(trifluorovinyl)ferrocene)] (2) and [Pt(η2-1,1′-bis(trifluorovinyl)ferrocene)(PPh3)2] (3) were achieved by ligand substitution in [Pt(η2-CH2?=?CH2)(PPh3)2]. Treatment of eneacarbonyldiiron with trifluorovinylferrocene provided [Fe(CO)4(η2-trifluorovinylferrocene)] (4). Photolytically activated reactions of [MnCp(CO)3] and [MnCp′(CO)3] (Cp′?=?C5H4CH3) afforded [MnCp(CO)2(η2-trifluorovinylferrocene)] (5a) and [MnCp′(CO)2(η2-trifluorovinylferrocene)] (5b) respectively. [Ni(η2-trifluorovinylferrocene)(Cy2P(CH2)2PCy2)] (6) could be obtained by reaction with [Ni(COD)2] and Cy2P(CH2)2PCy2. Furthermore the C[sbnd]F bond activation by oxidative addition in the presence of lithium iodide yielding two isomers of [PtI{η1-difluorovinylferrocene}(PPh3)2] (7a/7b) is presented. Molecular structures of 1, 4 and 7a were elucidated using X-ray single crystal diffraction. The spectroscopic and structural data of these complexes prove the powerful π acceptor abilities of these ligands.
- Heinrich, Darina,Schmolke, Willi,Lentz, Dieter
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p. 105 - 112
(2016/11/11)
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- Hydride-containing models for the active site of the nickel-iron hydrogenases
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The [NiFe]-hydrogenase model complex NiFe(pdt)(dppe)(CO)3 (1) (pdt = 1,3-propanedithiolate) has been efficiently synthesized and found to be robust. This neutral complex sustains protonation to give the first nickel-iron hydride [1H]BF4. One CO ligand in [1H]BF4 is readily substituted by organophosphorus ligands to afford the substituted derivatives [HNiFe(pdt)(dppe)(PR3)(CO)2]BF4, where PR 3 = P(OPh)3 ([2H]BF4); PPh3 ([3H]BF4); PPh2Py ([4H]BF4, where Py = 2-pyridyl). Variable temperature NMR measurements show that the neutral and protonated derivatives are dynamic on the NMR time scale, which partially symmetrizes the phosphine complex. The proposed stereodynamics involve twisting of the Ni(dppe) center, not rotation at the Fe(CO)2(PR3) center. In MeCN solution, 3, which can be prepared by deprotonation of [3H]BF4 with NaOMe, is about 104 stronger base than is 1. X-ray crystallographic analysis of [3H]BF4 revealed a highly unsymmetrical bridging hydride, the Fe-H bond being 0.40 A shorter than the Ni-H distance. Complexes [2H]BF4, [3H]BF4, and [4H]BF4 undergo reductions near -1.46 V vs Fc0/+. For [2H]BF4, this reduction process is reversible, and we assign it as a one-electron process. In the presence of trifluoroacetic acid, proton reduction catalysis coincides with this reductive event. The dependence of i c/ip on the concentration of the acid indicates that H2 evolution entails protonation of a reduced hydride. For [2H] +, [3H]+, and [4H]+, the acid-independent rate constants are 50-75 s-1. For [2H]+ and [3H]+, the overpotentials for H2 evolution are estimated to be 430 mV, whereas the overpotential for the N-protonated pyridinium complex [4H 2]2+ is estimated to be 260 mV. The mechanism of H 2 evolution is proposed to follow an ECEC sequence, where E and C correspond to one-electron reductions and protonations, respectively. On the basis of their values for its pKa and redox potentials, the room temperature values of ΔGH? and ΔGH- are estimated as respectively as 57 and 79 kcal/mol for [1H]+.
- Barton, Bryan E.,Rauchfuss, Thomas B.
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p. 14877 - 14885
(2011/01/05)
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- METHOD AND PREPARATION FOR TREATING BALDNESS
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Various embodiments of the present invention are directed to hair-loss, and include treatments and preparations. Embodiments of the present invention include bactericides, combinations of bactericides and fungicides, combination of bactericides and vasodilators, and combinations of bactericides, fungicides, and vasodilators that are delivered topically to pilosebaceous units within the scalps of persons suffering from hair loss. The treatment kills or controls microbes that disrupt hair growth by changing, inhibiting, or interrupting one or more biological functions of the pilosebaceous units. Certain embodiments of the present invention contain additional active and inactive ingredients, including anti-inflammatory agents, carriers, emulsifiers, antioxidants, and other such substances.
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- Complexes of four-membered group 13 metal(I) N-heterocyclic carbene analogues with metal carbonyl fragments
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The four-membered gallium(I) and. indium(I) heterocycles, [:M(Giso)] (M = Ga or In; Giso = [[N(Ar)I2CN(C6Hu)2)-, Ar = C6H3iPr2-2,6), were treated with a series of transition metal carbonyl
- Jones, Cameron,Stasch, Andreas,Moxey, Graeme J.,Junk, Peter C.,Deacon, Glen B.
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p. 3593 - 3599
(2009/12/02)
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- Biomimetic model featuring the NH proton and bridging hydride related to a proposed intermediate in enzymatic H2 production by fe-only hydrogenase
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Iron azadithiolate phosphine-substituted complex and its protonated species featuring the NH proton and/or bridging Fe hydride, [Fe2(μ- S(CH2)2NnPr(H)m(CH2) 2S)(M-H)n(
- Chiang, Ming-Hsi,Liu, Yu-Chiao,Yang, Shu-Ting,Lee, Gene-Hsiang
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p. 7604 - 7612
(2011/03/16)
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- Oxidative addition of thioesters to iron(0): active-site models for Hmd, nature's third hydrogenase
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The thioester Ph2PC6H4-2-C (O ) SPh reacts with Fe2(CO)9 to give [Ph2PC6H 4C(O)]Fe(SPh) (CO)3, a model for the CO-inhibited active site of the enzyme Hmd. T
- Royer, Aaron M.,Rauchfuss, Thomas B.,Gray, Danielle L.
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p. 3618 - 3620
(2009/12/08)
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- Extraction and recovery characteristics of Fe element from Nd-Fe-B sintered magnet powder scrap by carbonylation
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Iron element was extracted from the powder scrap of Nd-Fe-B sintered magnets via the carbonylation reaction with sulfur as a catalyst. The resultant carbonyl complex was Fe(CO)5 and the yield was evaluated to be ~56% by energy dispersion X-ray analysis. After applying the hydrogenation disproportionation treatment on the powder scrap, the extraction rate for Fe element was considerably accelerated on the resultant α-Fe/Fe2B/NdH2 (or neodymium oxides) nanocomposite powders to produce Fe(CO)5 in a maximum yield of ~92%.
- Miura, Koji,Itoh, Masahiro,Machida, Ken-Ichi
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p. 228 - 232
(2009/05/06)
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- Thermal properties and reactions towards nucleophiles of an iron complex displaying an acetyl and a pyruvoyl ligands
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Thermal evolution at 4 °C of the structurally characterized cis(CO)4Fe[C(O)C(O)CH3][C(O)CH3] (1(2)) gives rise to the cis(CO)4Fe[C(O)CH3]2 (1(3)) which, probably owing to synthetic problems, has never been described in the literature. By reaction with anionic nucleophiles (Nu-), 1(2) affords anionic trifunctionalized metallalactones {(CO)3Fe[C(O)CH3][C(O)C(CH3)(Nu)OC 7(O);(Fe-C7)]}- (3) formed by addition of the nucleophile reagent on the β carbon of the pyruvoyl moiety followed by the cyclization of this ligand on a terminal carbonyl of the complex. Anions 3 are characterized by 1H and 13C NMR and by X-ray diffraction for the complex with Nu = C(H)(CO2C2H5)2. Complexes 3 are also prepared by reaction of CH3Li with the neutral metallalactones (CO)4Fe[C(O)C(CH3)(Nu)OC7(O); Fe-7C] (2). The results of this study shed light on the reaction of cyclization of a pyruvoyl ligand as they clearly show that the presence of a second ligand (for example CO2R) with a labile OR group is not required to perform the formation of the metallalactone ring and then that the observed reaction has no connection with organic chain-ring transformations.
- Salaün, Jean-Yves,Rumin, René,Abbayes, Hervé des,Triki, Smail
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p. 3667 - 3678
(2007/10/03)
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- Radiolytic reduction of Fe(II) in 2-propanol
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The first reduction steps of iron (II) in 2-propanol have been studied by pulse radiolysis technique. The rate constant value of the reaction of solvated electron with iron (II) was found to be 4.8 × 109 dm3 mol-1 s-1. The absorption spectrum of Fe(I) with a maximum at 350 nm was determined. The radiolytic reduction of FeII in 2-propanol under an inert atmosphere leads to the formation of very small iron nanoparticles whereas under a CO atmosphere, the stable Fe(CO)5 complex is formed.
- Dey,Remita,Mostafavi
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- Pyrithione metal salts having defined particle size distribution and paint composition containing the same
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The present invention provides a pyrithione metal salts having a controlled particle size distribution to exhibit oil absorbency adequate for the paint formulation and a good dispersability in preparation of paint compositions, and a paint composition con
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Page/Page column 4-5
(2010/11/23)
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- Lewis base character of hydroxygermylenes for the preparation of heterobimetallic LGe(OH)M systems (M = Fe, Mn, L = HC[(CMe)(NAr)]2, Ar = 2,6-iPr2C6H3)
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LGeOH (1; L = HC[(CMe)(NAr)]2, Ar = 2,6-iPr2C 6H3) reacted with iron and manganese complexes to give LGe(OH)Fe(CO)4 (2) and LGe(OH)Mn(Cp)(CO)2 (3; Cp = cyclopentadienyl). Compounds 2 and 3
- Pineda, Leslie W.,Jancik, Vojtech,Colunga-Valladares, Juan F.,Roesky, Herbert W.,Hofmeister, Anja,Magull, Joerg
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p. 2381 - 2383
(2008/10/09)
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- Ring closure of alkoxycarbonyl(tetracarbonyl)pyruvoyliron complexes into metallalactones induced by nucleophilic attack of carbanions
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The reaction of carbanions with the pyruvoyl-substituted iron complex [(CO)4Fe(CO2CH3){C(O)C(O)CH3}] (1) affords the anionic trifunctionalized metallalactones [(CO)3Fe{C(O) C(CH3)(CRR′R″)OC4(O)(Fe-C4)} (CO2CH3)]- (3), whose formation results from the addition of the nucleophile to the β carbonyl of the pyruvoyl moiety, followed by attack of the oxygen of this β carbonyl on a terminal carbonyl ligand. These anionic lactones react, at low temperature, with HCl to give rise to the neutral lactones [(CO)4Fe{C(O)C(CH3) (CRR′R″)OC4(O)(Fe-C4)}] (2), which were previously obtained by addition of NuH nucleophiles to 1. Complex 3(3), whose lactonic ring formation has been performed using the diethyl malonate anion (R = R′ = CO2C2H5; R″ = H), and the dimethyl-substituted neutral lactone 2(1) (R = R′ = R″ = H) have been characterized by X-ray diffraction studies. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Cabon, Patrice,Rumin, Rene,Salauen, Jean-Yves,Des Abbayes, Herve,Triki, Smail
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p. 1515 - 1524
(2007/10/03)
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- Formation of anionic trifunctionalized metallalactones by nucleophilic addition at the β-carbonyl of a pyruvoyl ligand
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Anionic nucleophilic reagents Nu- = CH3O-, C2H5O-, t-BuO-, CH 3S-, and P(C6H5)2 - were found to react with (CO)
- Cabon,Rumin,Salauen,Triki,Des Abbayes
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p. 1709 - 1717
(2008/10/09)
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- Low-valent α-diimine iron complexes for catalytic olefin hydrogenation
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A family of low-valent α-diimine iron complexes has been synthesized and their utility in catalytic olefin hydrogenation reactions evaluated. Reduction of the ferrous dichloride complex [ArN=C(Me)C(Me)=NAr]FeCl2 (Ar = 2,6-(CHMe2)2-C6H3) with sodium amalgam in benzene or toluene furnished the iron arene complexes, [ArN=C(Me)C(Me)=NAr]Fe(η6-C6H5R) (R = H, Me). The solid-state structure of the toluene adduct revealed a contracted carbon-carbon backbone, short iron-imine bonds, and elongated imine nitrogen-carbon distances, suggesting significant reduction of the α-diimine ligand. The analogous reduction in alkane solvents afforded the bis(α-diimine) complex [ArN=C(Me)C(Me)=NAr]2Fe, which has also been crystallographically characterized. The arene complexes and the bis(a-diimine) complexes are inactive for catalytic olefin hydrogenation. Performing the reduction in the presence of internal alkynes such as diphenylacetylene and bis(trimethylsilyl)acetylene furnished the alkyne adducts [ArN=C(Me)C(Me)=NAr]Fe(η2-RC=CR) (R = Ph, SiMe3 ). Analogous olefin complexes with 1,5-cyclooctadiene and cycloctene have also been isolated using similar reduction procedures. The olefin adducts provide more active precatalysts than the alkyne compounds for the hydrogenation of 1-hexene. In each case, formation of rfarene adducts serves as a major catalyst deactivation pathway.
- Bart, Suzanne C.,Hawrelak, Eric J.,Lobkovsky, Emil,Chirik, Paul J.
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p. 5518 - 5527
(2008/10/09)
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- The transition metal carbonyl complexes of 1,3-bis(di-R-stibino)propanes (R = Me or Ph)
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The synthesis and characterisation of complexes of two distibinopropanes R2Sb(CH2)3SbR2 (R = Me or Ph) with a variety of metal carbonyls is described. These include cis-[M(CO) 4{R2Sb(CH2)3SbR2}] (M = Cr, Mo or W), [{Fe(CO)4}2{μ-R2Sb(CH 2)3SbR2}], [{Ni(CO)3} 2{μ-R2Sb(CH2)3SbR2}], [Co2(CO)6{Ph2Sb(CH2) 3SbPh2}], [Co2(CO)4{Me 2Sb(CH2)3SbMe2}3][Co(CO) 4]2 and [Mn2(CO)8{Ph 2Sb(CH2)3SbPh2}]. The complexes have been characterised by analysis, mass spectrometry, IR and multinuclear NMR spectroscopy as appropriate. Comparison of the spectroscopic data on these complexes with those of other stibine complexes and with complexes of Group 16 ligands has been used to establish the relative electronic properties of the distibines.
- Brown, Michael D.,Levason, William,Manning, Joanna M.,Reid, Gillian
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p. 1540 - 1548
(2007/10/03)
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- Reaction of [Fe(CO)4(η2-Me3SiC≡ CSiMe3)] with PMe3 - CO rather than alkyne substitution
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Reaction of [Fe(CO)4(η2-BTMSA)] (1) (BTMSA = Me3SiCCSiMe3) with trimethylphosphine proceeds by stepwise loss of CO ligands yielding [Fe(CO)3(PMe3) (η2-BTMSA)] (2) and [Fe(CO)sub
- Dennett, James N. L.,Ferguson, Michael J.,McDonald, Robert,Takats, Josef
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p. 862 - 868
(2007/10/03)
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- Unraveling the photochemistry of Fe(CO)5 in solution: Observation of Fe(CO)3 and the conversion between 3Fe(CO)4 and 1Fe(CO)4(solvent)
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The photochemistry of Fe(CO)5 (5) has been studied in heptane, supercritical (sc) Ar, scXe, and scCH4 using time-resolved infrared spectroscopy (TRIR). 3Fe(CO)4 (34) and Fe(CO)3(solvent) (3) are formed as primary photoproducts within the first few picoseconds. Complex 3 is formed via a single-photon process. In heptane, scCH4, and scXe, 34 decays to form 14·L (L = heptane, CH4, or Xe) as well as reacting with 5 to form Fe2(CO)9. In heptane, 3 reacts with CO to form 14·L. The conversion of 34 to 14·L has been monitored directly for the first time (L = heptane, kobs = 7.8(±0.3) x 107 s-1; scCH4, 5(±1) x 106 s-1; scXe, 2.1(±O.1) x 107 s-1). In scAr, 34 and 3 react with CO to form 5 and 34, respectively. We have determined the rate constant (kCO = 1.2 x 107 dm3 mol -1 s-1) for the reaction of 34 with CO in scAr, and this is very similar to the value obtained previously in the gas phase. Doping the scAr with either Xe or CH4 resulted in 34 reacting with Xe or CH4 to form 14·Xe or 14·CH4. The relative yield, [34]:[3] decreases in the order heptane > scXe > scCH4 ? scAr, and pressure-dependent measurements in scAr and scCH4 indicate an influence of the solvent density on this ratio.
- Portius, Peter,Yang, Jixin,Sun, Xue-Zhong,Grills, David C.,Matousek, Pavel,Parker, Anthony W.,Towrie, Michael,George, Michael W.
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p. 10713 - 10720
(2007/10/03)
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- Hydride participation in electron transfer processes between metal carbonyl anions and cations
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Kinetic studies of selected metal carbonyl anions establish their reactivity as nucleophiles or for electron transfer. The iron species, [HFe(CO)3L]- (L = CO, PPh3), behave as metal-centered nucleophiles when reacted with [M(CO)6]+ (M = Mn, Re). Determination of the deuterium kinetic isotope ratio from kinetic studies of [HFe(CO)4]- and [DFe(CO)4]-, kH/kD = 2.8, indicates primary isotope effects for reaction with Mn(CO)6+. Initial products from transfer of a CO and back transfer of two electrons are observed in some cases. For Re-(CO)6+ exclusive formation of HRe(CO)5 as a rhenium product strongly indicates a hydrogen transfer mechanism.
- Harrigan, Marcus J.,Atwood, Jim D.
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p. 846 - 849
(2008/10/09)
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- Contributions to the reactivity of phosphaalkynes with transition metal complexes - (see abstract) net Beitraege zum reaktionsverhalten von phosphaalkinen gegenueber uebergangsmetallkomplexen - (See abstract)
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The reaction of MesC≡P (Mes = 2,4,6-Me3C6H 2) with [(Ph3P)2Pt(η2-C 2H4)] leads to [(Ph3P)2Pt(η 2-PCMes)] (1) whereas with Fe2/su
- Himme, Daniel,Seitz, Markus,Scheer, Manfred
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p. 1220 - 1228
(2008/10/09)
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- Protonation studies of the new iron carbonyl cyanide trans-[Fe(CO) 3(CN)2]2-: Implications with respect to hydrogenases
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The new iron carbonyl cyanide trans-[Fe(CN)2(CO) 3]2-, [2]2-, forms in high yield via photosubstitution of Fe(CO)5 with 2 equiv of Et4NCN. Protonation of [2]2- generated [HFe(CN)
- Kayal, Ajay,Rauchfuss, Thomas B.
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p. 5046 - 5048
(2008/10/08)
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- Oriented long single walled carbon nanotubes on substrates from floating catalysts
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A new and feasible method to prepare long and well-oriented SWNTs on substrates in large scale is developed by applying a floating catalyst chemical vapor deposition (CVD) process. The catalysts for SWNT growth come from the decomposition of iron pentacarbonyl (Fe(CO)5) formed in situ from the reaction of iron powder and carbon monoxide gas. The growth of SWNTs is found to happen both on the substrate and in the gas flow. Both long and short nanotubes are formed on the substrates but only the long SWNTs are aligned by gas flow. The growth direction and the density of the long SWNTs can be easily controlled. In addition, long SWNTs can be cut and patterned using photolithography and water plasma etching techniques, offering a way to prepare patterned SWNTs with controllable orientation, density and lengths for various applications.
- Huang, Shaoming,Cai, Xianyu,Du, Chunsheng,Liu, Jie
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p. 13251 - 13254
(2007/10/03)
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- Specific formation of isocyanide iron complexes by reaction of primary carbamoyl ferrates with oxalylchloride
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Reaction of primary carbamoyl ferrates {(CO)4Fe[C(O)NHR]} - (R=Me, Et, allyl, decyl, cyclohexyl, t-butyl, benzyl, phenyl) with 1/2 equiv. of oxalylchloride affords cis-bis-carbamoyl intermediates: (CO) 4Fe[C(O)NHR]2 which thermally give rise, in good yields, to the mono-isocyanide complexes (CO)4Fe(CNR). The mechanism of the reaction is discussed. Via a similar process, an alkoxycarbamoyl intermediate (CO)4Fe[C(O)NHR](CO2Me) affords Fe(CO)5 and 1,3-dialkylurea.
- Luart, Denis,Salaün, Jean-Yves,Patinec, Véronique,Rumin, René,Des Abbayes, Hervé
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p. 656 - 660
(2008/10/08)
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- Synthesis and characterization of high-spin [(CO)3FeII(CO2R)3]2Fe II complexes formed by thermolysis of cis-(CO)4Fe(CO2R)2 (R = Me, t-Bu, allyl, 1,1′-dimethylallyl). X-ray crystal structure of the allyl derivative
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Instead of the expected carbon-carbon coupling into oxalates, thermolysis at 30 °C of the cis-bis(alkoxycarbonyl) monomers (CO)4Fe(CO2R)2 (1) affords the novel trimetallic compounds [(CO)3Fe(μ,η2-CO2R)3]2 Fe (R = Me (2a), t-Bu (2b), allyl (2c), 1,1′-dimethylallyl (2d)). As shown by 1H and 13C NMR, these complexes 2, which can be described as a central Fe(II) surrounded by two [(CO)3Fe(CO2R)3]- ligands, are paramagnetic. A Mo?ssbauer study of 2a and 2d revealed that these complexes display a high-spin configuration of their central iron atom and a low-spin configuration of the two lateral iron atoms. The easy formation of these complexes 2 by reacting fac-[(CO)3Fe(CO2R)3]- anions with FeCl2 suggests that formation of 2 by thermal evolution of 1 could occur via an associative mechanism, giving rise to the [(CO)3Fe(CO2R)3] pattern. Further thermolysis of 2 at 50 °C affords alcohols, Fe(CO)5, carbon monoxide, and bis(alkyl carbonates).
- Le Gall, Nathalie,Luart, Denis,Salaün, Jean-Yves,Talarmin, Jean,Des Abbayes, Hervé,Toupet, Lo?c,Menendez, Nieves,Varret, Fran?ois
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p. 1775 - 1781
(2008/10/08)
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- Chemical method of making a suspension, emulsion or dispersion of pyrithione particles
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A method for producing a suspension, emulsion or dispersion of de-agglomerated particles (advantageously submicron-sized particles) of pyrithione salts comprising contacting agglomerated pyrithione salt particles with a de-agglomerating agent to produce t
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- Cyclization of the pyruvyl(methoxycarbonyl)tetracarbonyliron complex cis-(CO)4Fe[C(O)C(O)CH3](CO2CH3) induced by pronucleophile reagents
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Two iron complexes, cis-(CO)4Fe[C(O)C(O)CH3](CO2CH3) (1a) and cis-(CO)4Fe[C(O)CO2-CH2] [C(O)CH2] (3), are reported. Each complex can be considered as a λ-keto ester with a metal atom inserted into the chain linking its two organic groups. 1a is the only one found to evolve thermally, similarly to organic λ-keto esters, into the methoxy metallalactone (CO)4FeC(O)C(CH3)(OCH3)OC(O) (2a). This reaction is not reversible and does not require any acid or alkaline catalysis. The process does not result from a spontaneous dissociation of the methoxycarbonyl ligand of la but from an associative intra or intermolecular mechanism. A similar process can also be induced by pronucleophile reagents, and it affords a series of substituted metallalactones: (CO)4FeC(O)C(CH3)(Nu)OC(O) (Nu = OCH3 (2a), OC2H5 (2b), SC2H5 (2c), P(C6H5)2 (2d), P(C6H11)2 (2e)). Complex 2e has been characterized structurally. These substituted lactones are formed by nucleophilic attack of the reagent at the pyruvyl β-carbonyl followed by carbonylate attack on the alkoxycarbonyl ligand.
- Gabon, Patrice,Sellin, Murielle,Salaün, Jean-Yves,Patinec, Véronique,Des Abbayes, Hervé,Kubicki, Marek M.
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p. 2196 - 2202
(2008/10/08)
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- A new approach to studying the mechanism of catalytic reactions: An investigation into the photocatalytic hydrogenation of norbornadiene and dimethylfumarate using polyethylene matrices at low temperature and high pressure
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This paper presents a new method for investigating the mechanisms of homogeneously catalyzed reactions involving gases, particularly H2. We show how the combination of polyethylene (PE) matrices and high pressure - low temperature (HPLT) experiments can be used to provide new mechanistic information on hydrogenation processes. In particular, we show how we are able to generate reaction intermediates at low temperature, and then to extract the contents of the PE film at room temperature to characterize the organic products using GC-MS. We have used our new technique to probe both the hydrogenation of dimethyl fumarate (DF), using Fe(CO)4(η2-DF) as the catalytic species, and the hydrogenation of norbornadiene (NBD), using (NBD)M(CO)4 (M = Cr or Mo) as the catalytic species. Irradiation of Fe(CO)4(η2-DF) in a PE matrix at 150 K resulted in the formation of an intermediate complex tentatively assigned Fe(CO)3(η4-DF). Warming this complex to 260 K under H2 leads to the formation of Fe(CO)3(η2-DF)(η2-H2). Further warming of the reaction system results in the hydrogenation of the coordinated DF, to generate dimethyl succinate (DS). Characterization of the intermediate species was obtained using FTIR spectroscopy. Formation of DS was confirmed using both FTIR spectroscopy and GC-MS analysis. UV photolysis of (NBD)M(CO)4 in PE under H2 in the presence of excess NBD results in the formation of the hydrogenated products norbornene (NBN) and nortricyclene (NTC), with trace amounts of norbornane (NBA) being observed. These products were in similar ratios to those observed in fluid solution. However, for (NBD)Mo(CO)4, the relative amounts of the organic products change considerably when the reaction is repeated in PE under H2 in the absence of free NBD, with NBA being the major product. The use of our HPLT cell allows us to vent and exchange high pressures of gases with ease, and as such we have performed gas exchange reactions with H2 and D2. Analysis of the reaction products from these exchange reactions with GC-MS provides evidence for the mechanism of formation of NBA, in both the presence and absence of excess NBD, a reaction which has been largely ignored in previous studies.
- Childs,Cooper,Nolan,Carrott,George,Poliakoff
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p. 6857 - 6866
(2007/10/03)
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- Non-spherical and non-platelet crystalline forms of pyrithione salts
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The present invention relates to non-spherical and/or non-platelet pyrithione particles. Also disclosed is a method for producing non-spherical and/or non-platelet particles of pyrithione salts, comprising reacting pyrithione or a water-soluble salt of py
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- Synthesis of bis-(acyl, carbamoyl or alkoxycarbonyl) iron monomer or dimer complexes by reaction of oxalyl chloride with various tetracarbonyl ferrates: (Fe[C(O)R](CO)4)-
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The reaction of oxalyl chloride with various tetracarbonyl ferrates bearing a carbonylated organic ligand induces the formation of bis substituted monomers Fe[C(O)R]2(CO)4 or dimers (Fe[C(O)R](CO)4)2 and of bis-[μ,η2-C(O)R]Fe2(CO)6 bridged dimers. The orientation of the reaction depends on the nature of the organic ligand of the ferrates. Thus carbamoyls or alkoxycarbonyls ferrates bearing mobile R groups are found to induce the formation of bis substituted monomers while bulky alkoxycarbonyl ligands afford non-bridged dimers. Acyls and bulky carbamoyls give rise to dimers bearing bridging acyls or carbamoyls. The mechanisms of formation of these different complexes and the possible thermal interconversions of these compounds are investigated.
- Luart, Denis,Le Gall, Nathalie,Salaün, Jean-Yves,Toupet, Lo?c,Des Abbayes, Hervé
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p. 166 - 177
(2008/10/08)
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- Reactions of 1,1,3,3-tetramethyldisilazane with dicobalt octacarbonyl and iron pentacarbonyl. Thermal decomposition of the cobalt and iron carbonyl silazane complexes
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The reaction of (HMe2Si)2NH with Co2(CO)8 gives the complex [Co2(CO)7(SiMe2)2NH 2]+[Co(CO)4]-. Its thermal decomposition starts with dissociation into the acid HCo(CO)4 and the base Co2(CO)7(SiMe2)2NH. After that, the base and the initial complex decompose further under the action of HCo(CO)4. The final products of this reaction are CO, NH3, Co, volatile dimethylcyclosilazane, and a solid residue consisting of cobalt particles encapsulated into a polymethylsiloxane matrix and possessing properties of mixed para-and ferromagnetics with an ultimate specific magnetization of 64-74 G g-1. Tetramethyldisilazane reacts with iron pentacarbonyl under UV irradiation to give relatively stable 1,3-bis(tetracarbonylhydrideiron)-1,1,3,3-tetramethyldisilazane. This product contains Fe - H...N hydrogen bonds, which stabilize it against dehydrogenation and cyclization to diironcyclodisilazane. Thermal decomposition of this product was investigated.
- Semenov,Ladilina,Khorshev,Makarenko,Kurskii,Bochkova
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p. 2455 - 2462
(2007/10/03)
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- On the reaction of KPPh2 with Fe(CO)5 and Fe(CO)4CS; molecular structure of [(CO)4FePPh2]-
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Fe(CO)5 reacts with [PPh2]- in THF at -78 °C to give the adduct [(CO)4FeCOPPh2]- (3) which decomposes at elevated temperature to give [(CO)4FePPh2]- (1), [Fe2(CO)8]2- (2) and (Ph2P)2 probably via a radical mechanism. Attempts to transfer 3 with the electrophiles MeSO3CF3 or Me3SnCl into the corresponding carbenes have failed and Fe(CO)5 along with Ph2PMe and Me3SnPPh2, respectively, are formed. 1 adds one equivalent of CS2 to generate [(CO)4FePPh2CS2]- (4). The [K-18-Krone-6] salt of 1 crystallizes in the triclinic space group P 1 with the unit cell parameters a = 929.5(2), b =1112.1 (2), c - 2017.9(4) pm, α = 100.29(3)°; β = 94.07(3)°; γ = 114.58(3)°. The existence of 3 is established by low temperature 31P NMR spectroscopy.
- Petz, Wolfgang,Weller, Frank
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p. 715 - 721
(2007/10/03)
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- 1,3-dipolar cycloaddition to the Fe-N=C fragment. 17.1 diastereoselectivity with C2- and non-C2-symmetric chirally N-substituted α-diimine ligands, R*-N=C(H)-C(R′) =N-R* and C5H4N-2-C(R′)=N-R*, with dimethyl acetylenedicarboxylate (DMAD) and methyl propiolate (MP).
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The 1,3-dipolar cycloaddition reaction of Fe[R*-DAB(H;H)](CO)3 (6k; R*-DAB(H;H) = R*-N=C(H)-C(H)=N-R*) with dimethyl acetylenedicarboxylate (DMAD), in which the R*-DAB(H;H) ligand is C2-symmetric and is chirally N-substituted, gives the two expected diastereomers with low diastereoselectivity, due to a small difference in the rate constants of the two reactive C=N groups in 6k exposing their re and si faces, respectively. The 1,3-dipolar cycloaddition reaction of Fe(α-diimine)(CO)3 (1, 6m) with DMAD and methyl propiolate (MP), in which a non-C2-symmetric α-diimine ligand (R*-DAB(H;Me) and Py-2-C(R′)=N-R* (R*,R′-PyCa) is chirally N-substituted, gives the two expected diastereomers with medium to high diastereoselectivity. The diastereoselectivity with the non-C2-symmetric α-diimine ligands, which have only one reactive imino group, depends on the size of the chiral group R*, the distance of the chiral group to the reacting centers, and the type of dipolarophile. The two starting complexes (1 and 6m) exist in solution in the form of two - rapidly interconverting diastereomeric conformers I and II. In contrast to the C2-symmetric case, the free energies of activation for the two different conformers and their respective concentrations may be quite different here. The diastereoselectivities could not be influenced by variation of temperature, solvent, or the additional ligand. Kinetic resolution by a cycloreversion reaction could be excluded by the use of a chiral additional ligand and an achiral α-diimine ligand (i-Pr, H-PyCa, or i-Pr-DAB(H; H)). X-ray crystal structures have been determined from the respective diastereomeric mixtures of the pyrrolinone complex 5cks and the [2.2.2] bicyclic product 7aks. The structures of the [2.2.2] bicyclic product 4aks and of the free pyrrolinone ligand 8als have been determined using diastereomerically pure products. The 5-(2-pyridyl)pyrrolin-2-one ligands 8 are decomplexed from their precursors 5 by Me3NO, air oxidation, exchange by CO, and oxidative reactions with dihalogens or H2O2.
- Feiken, Nantko,Schreuder, Pieter,Siebenlist, Ron,Frühauf, Hans-Werner,Vrieze, Kees,Kooijman, Huub,Veldman, Nora,Spek, Anthony L.,Fraanje, Jan,Goubitz, Kees
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p. 2148 - 2169
(2008/10/08)
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- Chain-ring isomerism vs. carbon-carbon coupling on two (tetracarbonyliron)-γ-ketoesters: Cis-[Fe(COR)(COCOR′)(CO)4] (R = Me, R′ = OMe; R = OMe, R′ = Me)
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Ferra-γ-ketoesters 1 and 2 induce thermally either a carbon-carbon coupling process or a chain-ring isomerization; the orientation of the reaction likely depends on the proximity of the ester group to the metal centre.
- Sellin, Murielle,Luart, Denis,Salauen, Jean-Yves,Laurent, Pascale,Toupet, Loic,Des Abbayes, Herve
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p. 857 - 858
(2007/10/03)
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- Charge-transfer crystals of octacarbonyldiferrate. Solid-state structure and oxidation-reduction of an iron-iron-bonded electron donor
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The dinuclear carbonylmetalate [Fe2(CO)8]2- forms deeply colored crystals A2[Fe2(CO)8] with various phosphonium and pyridinium cations (A+) by metathesis in aqueous solution. Diffuse reflectance absorption spectroscopy and X-ray crystallography establish the colors to derive from anion-to-cation charge-transfer (CT) within the triple ion [A+, Fe2(CO)82-, A+] extant in the solid state. Partial electron transfer in the charge-transfer salts is established by the significant shortening of the iron-iron bond in the [Fe2(CO)8]2- moiety when it is ion paired with the N-methyllutidinium acceptor. In solution, the charge-transfer salts can undergo interionic electron transfer, and they lead to the dimeric A2 and a series of iron carbonyl products that are uniquely dependent on the solvent (water, ether, and acetonitrile).
- Bookman,Cho,Kochi
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p. 5221 - 5231
(2008/10/09)
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- Chemical Behaviour of the Mixed-metal Carbonyl Clustrs (1-) and (2-). Crystal Structures of (1-) and >(1-)
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Addition of triphenylphosphine to the cluster (1-) yielded the derivative (1-), which is stable enough to allow a single-crystal X-ray analysis on the (1+) salt.The cluster contains a triangular metallic framework, the vertices of which are occupied by two Fe(CO)4 groups and one Rh(CO)(PPh3) moiety; the unsaturation of the cluster (46 valence electrons) is brought about by this 16-electron square-planar fragment.The cluster (2-) was obtained by treating with (1-) (molar ratio 1 : 2) in refluxing acetone, and was characterized by infrared spectroscopy and elemental analyses.The adduct >(1-) was prepared by stoichiometric addition of in acetone and the crystal structure of the (1+) salt was elucidated by X-ray analysis.The cluster contains a trigonal-bipyramidal arrangement of metal atoms, with one Au(PPh3) and one Fe(CO)3 group occupying the apical positions.The vertices of the FeRh2 equatorial plane are bound to two terminal carbonyl ligands, and the edges are spanned by three bridging carbonyls.The 31P NMR spectral data for (1-) and >(1-) are consistent with the solid-state structures, but do not exclude the presence of fluxional processes in solution.
- Pergola, Roberto Della,Fracchia, Lucia,Garlaschelli, Luigi,Manassero, Mario,Sansoni, Mirella
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p. 2763 - 2768
(2007/10/03)
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- Radical processes in the reduction of nitrobenzene promoted by iron carbonyl clusters. X-ray crystal structures of [Fe3(CO)9(μ3-NPh)]2-, [HFe3(CO)9(μ3-NPh)]-, and the
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The halides Cl-, Br-, and I- and the pseudo-halide NCO- react with Fe3(CO)12 (1) in aprotic solvents to induce a disproportionation reaction yielding the radical anion [Fe3(CO)s
- Ragaini, Fabio,Song, Jeong-Sup,Ramage, David L.,Geoffroy, Gregory L.,Yap, Glenn A. P.,Rheingold, Arnold L.
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p. 387 - 400
(2008/10/08)
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- Synthesis and reactivity of bis(alkyloxalyl) and alkoxycarbonyl alkyloxalyl iron complexes and (R, R'=Me or Et): evidence for reductive elimination of oxalate
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The new complexes cis- (R=Me or Et) and cis- (R,R'=Me, Et or i-Pr) have been synthesized.The bis-(alkyloxalyl) complexes decarbonylate at +12 deg C to their alkoxycarbonyl alkyloxalyl homologues.The latter decompo
- Laurent, Pascale,Salauen, Jean-Yves,Gall, Gwenaeelle Le,Sellin, Murielle,Abbayes, Herve des
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p. 175 - 184
(2007/10/02)
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- Energetics and mechanism of the thermal decarboxylation of (CO)4FeCOOH- in the gas phase
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The energetics and mechanism of decarboxylation of (CO)4FeCOOH- to form CO2 and (CO)4FeH-, a key step in the Fe(CO)5-catalyzed water-gas shift reaction, is investigated using the flowing afterglow-triple quadrupole technique. Previous studies of collisional activation of (CO)vFeCOOH- in the gas phase showed only loss of CO ligands, suggesting that base catalysis is necessary for decarboxylation. We have now observed gas-phase decarboxylation of this hydroxycarbonyl km using energy-resolved collision-induced dissociation. Decarboxylation competes with decarbonylation at translational energies near the reaction threshold, indicating that unimolecular β-elimination of CO2 can occur. Loss of two carbonyl ligands to form (CO)3FeOH- is the dominant process at somewhat higher energies. The thresholds for loss of CO, 2CO, and CO2 are 21.4 ± 3.9, 30.2 ± 2.8, and 18.9 ± 3.2 kcal/mol, respectively. The latter number corresponds to a barrier for an exothermic reaction. DH[Fe(CO)5-OH-] = 60.8 ± 3.4 kcal/mol is determined by measurement of the equilibrium constant for hydroxide exchange between Fe(CO)5 and SO2. (CO)4FeSOOH- + CO2 is formed as a side product of this reaction, and the structure of this species is investigated. These data are combined with other thermochemistry to derive a model reaction-energy profile for the Fe(CO)5-catalyzed water-gas shift reaction.
- Sunderlin,Squires, Robert R.
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p. 337 - 343
(2007/10/02)
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- C-H bond-making and -breaking processes in heteronuclear monoazadienyl complexes: Reactivity of HFeRu(CO)5{RC=C(H)C(H)=N-iPr} toward CO
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In the photochemically induced reaction of Ru2(CO)6{RC=C(H)CH2N-iPr} (1a, R = Ph; 1b, R = Me) with Fe2(CO)9 the heteronuclear complex HFeRu(CO)5{RC=C(H)C(H)=N-iPr} (5) is formed in 35 % yield. HRu2(CO)6{RC=C(H)C(H)=N-iPr} (4), which is prepared quantitatively by photolysis of H2Ru4(CO)8{RC=C(H)C(H)=N-iPr}2 under a CO atmosphere, can act as an intermediate in this reaction and is proposed to be formed from 1 by a β-H-elimination reaction. Complex 5 is most likely formed via oxidative addition of the Ru-H bond in 4 to a Fe(CO)4 fragment. Complex 5 reacts with CO at 293 K to give reductive elimination of the monoazadiene ligand and formation of Fe(CO)5/Ru3(CO)12, probably via a mechanism involving opening of the hydride bridge. In the reaction of 5 with CO at 373 K the hydride is shifted to the monoazadienyl (MAD-yl) ligand, which is reduced from formally monoanionic to dianionic. In the case of R = Ph selective hydride transfer to Cβ is observed, resulting in the formation of FeRu(CO)6-{PhC(H)C(H)C(H)N-iPr} (6a), which features an unprecedented coordination mode of the MAD-yl ligand. For R = Me, both transfer to Cβ (affording 6b) and to Cim is observed, the latter affording FeRu(CO)6{MeC=C(H)CH2N-iPr} (7). This R-group dependence and also the difference in the reactivity of 5 and its homonuclear Ru2 analogue 2 is rationalized by the strength of the π-C=C coordination in the intermediate HFeRu(CO)6{RC=C(H)C(H)=N-iPr} (9). Complex 9a could not be prepared by the reaction of [FeRu(CO)6(PhC=C(H)C(H)=N-iPr}][BF4] (8a) with NaBH4, which afforded one diastereomer of FeRu(CO)6{PhCC(H)C(H)N-(H)-iPr} (10a), but 9a was formed by the conversion of 8a on silica. The X-ray crystal structures of 6a and 9a have been determined. Crystals of 6a are monoclinic, space group P21/c, with unit-cell dimensions a = 12.106(14) A?, b = 9.490(10) A?, c = 16.780(7) A?, β = 97.61(7)°, V = 1911(3) A?3, Z = 4, final R = 0.055, and Rw = 0.040 for 2215 reflections with I > 3.0σ(7) and 245 parameters. Crystals of 9a are orthorhombic, space group P212121, with a = 9.819(1) A?, b = 11.928(1) A?, c = 17.338(1) A?, V = 2030.7(3) A?3, Z = 4, and final R = 0.044 for 1434 reflections with I > 2.5σ(7) and 254 parameters. The most important conclusion of this work is that isostructural FeRu- and Ru2-MAD-yl complexes show a large difference in reactivity, which can be rationalized by stronger π-coordination of the MAD-yl ligand to Fe as compared to Ru.
- Beers, Olaf C. P.,Elsevier, Cornelis J.,Kooijman, Huub,Smeets, Wilberth J. J.,Spek, Anthony L.
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p. 3187 - 3198
(2008/10/08)
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- Synthesis of the square-bipyramidal cluster 4-SiMe)2(CO)11> by two routes and its reaction with GeMe2H2. The crystal structures of 4-SiMe)2(CO)11> and 4-SiMe)2(CO)10>
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4-SiMe)2(CO)11> (1a) is the major product from the reaction of with (synthesised from SiMeH2Cl and Na2).An alternative, quantitative synthesis of 1a is from SiMeH3 and , 1a reacts with an
- Anema, Skelte G.,Lee, Siew Kim,Mackay, Kenneth M.,Nicholson, Brian K.
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p. 211 - 218
(2007/10/02)
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- Structure and spectra of 4,5-μ-tetracarbonyliron-hexaborane(10), Fe(CO)4B6H10, and its conjugate base, [Fe(CO)4B6H9]-
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The chemistry of B6H10Fe(CO)4 (I) and its conjugate base [B6H9Fe(CO)4]- (II) has been extended. 11B and 1H NMR spectra and the crystal and molecular structure of I are reported. I crystallizes in the orthorhombic space group Pbca, with a = 11.441(3) ?, b = 11.696(4) ?, c = 16.396(3) ?, and Z = 8. The crystal structure determination of this air-sensitive species indicates that the cage geometry is not substantially different from that of the parent borane. The position of the Fe atom is well below the basal B5 plane, the dihedral angle being 55.7°. The angles around the Fe atom suggest trigonal-bipyramidal geometry with the axial Fe-C bond diverging from linearity by ca. 6°. I is readily deprotonated with KH to afford the conjugate base [B6H9Fe(CO)4]- (II). Variable-temperature NMR spectra for II indicate complex dynamic processes, and the data are interpreted in terms of fluxional motion of the bridging H atoms, which is quenched at ca. -130°C, and also of the borane cage relative to the Fe(CO)4 moiety, which is quenched at ca. -10°C. Two processes are identifed for the former: complete scrambling of the three bridging H atoms among the four available sites above -50°C and a process that is partially quenched in which only one H atom moves above -100°C.
- Srivastava, Dileep K.,Rath, Nigam P.,Barton, Lawrence,Ragaini, James D.,Hollander, Orin,Godfroid, Robert,Shore, Sheldon G.
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p. 2017 - 2024
(2008/10/08)
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- Synthesis, reactivity of the dialkoxycarbonyl carbonyl iron complexes (L = CO or PPh3; R = CH3, C2H5), and an easy access to +
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The cis-dialkylcarboxytetracarbonyliron complexes were readily obtained from reaction of oxalyl chloride with the corresponding tetracarbonylcarboxyiron anion - (R = Me, 1a; R = Et, 1b). 1a underwent a clean ligand exchange with triphenylphosphine to give (2).Neither 1a nor 2 yielded dimethyl oxalate after thermolysis; rather, a mixture of methanol and methyl carbonate was obtained.The mobility of the alkoxy groups on 1 was shown by several exchange experiments.A clean reaction of the tetrafluoroboric acid ether with 1a gave + which was isolated and characterized by IR, 1H, and 13C NMR spectroscopy.
- Salauen, Jean-Yves,Gall, Gwenaeelle le,Laurent, Pascale,Abbayes, Herve des
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- Electron transfer between mononuclear metal carbonyl anions (M(CO)5-, M = Mn, Re; CpFe(CO)2-; CpM(CO)3-, M = Cr, Mo) and trinuclear clusters (M3(CO)12, M = Fe, Ru, Os) and between trinuclear dianions (M3(CO)112-, M = Fe, Ru, Os) and metal carbonyl dimers (Mn ...
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Full title: Electron transfer between mononuclear metal carbonyl anions (M(CO)5-, M = Mn, Re; CpFe(CO)2-; CpM(CO)3-, M = Cr, Mo) and trinuclear clusters (M3(CO)12, M = Fe, Ru, Os) and between trinuclear dianions (M3(CO)112-, M = Fe, Ru, Os) and metal carbonyl dimers (Mn2(CO)10 and Cp2M2(CO)6, M = Cr, Mo, W). Reaction of mononuclear metal carbonyl anions with trinuclear clusters of group 8 (M3(CO)12, M = Fe, Ru, Os) at ambient conditions leads to four separate outcomes: (1) formation of the metal carbonyl dimer and the trinuclear dianion which occurs whenever the two-electron reduction potential for the dimer is more negative than for the trinuclear cluster, (2) formation of MFe2(CO)7- by elimination of Fe(CO)5 which occurs for M = Re(CO)5, Mn(CO)5, and CpMo(CO)3, (3) formation of the adduct, MRu3(CO)11-, which occurs for Re(CO)5, and (4) no reaction when the two-electron reduction potential for the trinuclear complex is more negative than for the dimer. For complexes where the two-electron potential for the cluster is more negative than for the dimer, reaction of M3′(CO)112- with M2 to give M3′(CO)12 and 2M- is observed. The observed reactions allow an estimate of the two-electron reduction potentials for the trinuclear clusters. The kinetics of all of these reactions indicate a first-order dependence on the oxidant and on the reductant and are most consistent with outer-sphere electron transfer.
- Shauna Corraine,Atwood, Jim D.
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p. 2647 - 2651
(2008/10/08)
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- Group- and electron-transfer reactions of tetracarbonylferrate(2-)
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Reactions of Fe(CO)42- with metal carbonyl complexes lead to distinct mechanisms. Reaction with metal carbonyl cations gives a two-electron process that we interpret as a CO2+ transfer. Reaction with Mn2(CO)10 occurs by a single-electron transfer producing Fe2(CO)82- and Mn(CO)5-. Reaction with Mn(CO)5Br also occurs by a single-electron transfer. Reaction with Re(CO)5Br could be either SET or direct nucleophilic displacement. Kinetic studies are reported for several reactions.
- Zhen, Yueqian,Atwood, Jim D.
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p. 2778 - 2780
(2008/10/08)
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