- Cleavage of acylcobalt carbonyl with hydridocobalt tetracarbonyl
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The reaction CH3(CH2)4COCo(CO)4 + HCo(CO)4 → CH3(CH2)4CHO + Co2(CO)8 proceeds with second-order kinetics (first order in each reactant), k2
- Azran, Jacques,Orchin, Milton
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- Synthesis of tetranuclear mixed-metal clusters via the reaction of [Co(CO)4]- with closed metal carbonyl trimers. Crystal and molecular structure of [(Ph3P)2N][CoRu3(CO)13]
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The new clusters HCoRu3(CO)13, HCoRu2Os(CO)13, HCoRuOs2(CO)13, and HCoOs3(CO)13 have been synthesized by allowing K[Co(CO)4] to react with Ru3(CO)12, Ru2Os(CO)12, RuOs2(CO)12, and Os3(CO)12, respectively, followed by protonation. Reaction of K[Co(CO)4] with Fe3(CO)12, Fe2Ru(CO)12, and FeRu2(CO)12 followed by acidification did not lead to the desired hydrido mixed-metal clusters but instead to various other products. Reaction of [PPN][Co(CO)4] (PPN = (Ph3P)2N) with Fe3(CO)12 and Ru3(CO)12 without subsequent acidification gave the salts [PPN][CoFe3(CO)13] and [PPN][CoRu3(CO)13]. The latter was structurally characterized by single-crystal X-ray diffraction. It crystallizes in the space group P1 with Z = 2 and unit cell dimensions a = 9.783 (5) ?, b = 14.768 (5) ?, c = 18.675 (5) ?, α = 110.39 (3)°, β = 99.02 (4)°, γ = 91.44 (4)°, and V = 2489 (4) ?3. Diffraction data (0° w = 0.044 for 6150 independent reflections with I ≥ 3.0σ(I). The molecule contains a tetrahedral CoRu3 core with each Ru atom bonded to three terminal carbonyls, the Co atom bonded to one terminal carbonyl, and a carbonyl ligand bridging each of the three Co-Ru bonds. Analogous reactions of [PPN] [Co(CO)4] with Fe2Ru(CO)12 and FeRu2(CO)12 gave products formulated as [PPN][CoFe2Ru(CO)13] and [PPN][CoFeRu2(CO)13], but these salts were not obtained pure.
- Steinhardt, Paul C.,Gladfelter, Wayne L.,Harley, A. Dale,Fox, Joseph R.,Geoffroy, Gregory L.
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- THE PREPARATION OF ACYLTETRACARBONYLCOBALT COMPOUNDS FROM KETENES AND HYDRIDOTETRACARBONYLCOBALT
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Ketenes (R1R2C=C=O, R1, R2= H or alkyl)react rapidly at -79 deg C with hydridotetracarbonylcobalt in a 1/1 molar ratio to form quantitatively the corresponding acyltetracarbonylcobalts, which can be isolated in good to exellent yields.Electron-withdrawing substituents in the ketene lower the reactivity towards HCo(CO)4.
- Ungvary, Ferenc
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- REACTION OF METHOXY KETALS AND DIMETHYL CARBONATE WITH SYNTHESIS GAS.
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The reaction of dimethoxy ketals and dimethyl carbonate with synthesis gas results in the formation of acetaldehyde. In the case of methoxy ketals, the reaction is carried out with a cobalt catalyst at 130 degree C and 2500 psi. Th rate of acetaldehyde formation is 4. 0 M h** minus **1. The reaction of dimethyl carbonate requires a cobalt-iodide catalyst and operating conditions of 180 degree C and 4000 psi. In this case, the rate of formation of acetaldehyde approaches 30 M h** minus **1. Mechanisms are discussed which are consistent with results obtained from high pressure infrared studies and stoichiometric model reactions.
- Wegman,Letts
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- THE REACTION OF TRIPHENYLCARBINOL WITH HCo(CO)4
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The reaction of Ph3COH with 2 mol of HCo(CO)4 gives Ph3CH in quantitative yield.The reaction is cleanly second order (k2 = 2.50 x 10-4 l mol-1 s-1, in CH2Cl2 at 20 deg C), first order with respect to each reactant.The rate increases markedly with increase in solvent polarity, suggesting Ph3C+ as an intermediate.The rate of the reaction of HCo(CO)4 with Ph3CBF4 is more than 103 as fast as with Ph3COH.No evidence for the functioning of HCo(CO)4 as a hydride donor could be secured.
- Matsui, Yasushi,Orchin, Milton
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- Octacarbonyl dicobalt-catalyzed selective transformation of ethyl diazoacetate into organic products containing the ethoxycarbonyl carbene building block
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In the presence of 1 mol% octacarbonyl dicobalt ethyl diazoacetate can be transformed at room temperature and carbon monoxide pressure selectively into diethyl 2-diazo-3-oxo-pentanedicarboxylate or in the presence of an alcohol (methanol, ethanol, tert-bu
- Tuba, Robert,Ungváry, Ferenc
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- Electrochemical synthesis and structure of Sn[Co(CO)4]4 and its use as a stable precursor of [Co(CO)4]- for the catalysis of hydrolysis of propylene carbonate
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The complex Sn[Co(CO)4]4 (I) has been prepared in high yield by the controlled potential electrolysis of Co2(CO)8 in the presence of a tin anode. The major advantage afforded by this electrochemical synthesis is to produce I quickly and cleanly. Results of an X-ray diffraction study on I are reported. We have established that I and Co2(CO)8 are very active catalysts for the hydrolysis of cyclic organic carbonates. The 100% selectivity in mpnoglycol is in marked contrast to other catalytic systems that require an excess of water to inhibit production of polyglycols. Studies, under various CO pressures, of the catalytic activities of Co2(CO)8 and I during the hydrolysis of propylene carbonate have led us to suggest that (i) [Co(CO)4]- is the active moiety, (ii) I can eliminate Co2(CO)8, and (iii) I is more stable than Co2(CO)8 at low CO pressures. Isotopic analysis of the remaining substrate and products after the hydrolysis of propylene carbonate by H218O show that (iv) the attack of water occurs at the carbonyl site of the carbonate and (v) it is likely that hydration is activated by [Co(CO)4]-.
- Cabrera, Armando,Samain, Henri,Mortreux, André,Petit, Francis,Welch, Alan J.
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p. 959 - 964
(2008/10/08)
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- Benzyltitanium and -zirconium cobalt carbonyls. Preparation and spectroscopic characterization
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Tetrabenzyltitanium (1a) and -zirconium (1b) react with equimolar HCo(CO)4 (2) to give the corresponding tribenzylmetal-cobalt tetracarbonyl (M = Ti, 5a; M = Zr, 5b) derivatives. Compounds 5 also can be obtained from (PhCH2)3/s
- Bartik, Tamás,Happ, Berit,Sorkau, Angela,Thiele, Karl-Heinz,Pályi, Gyula
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p. 558 - 560
(2008/10/08)
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- Reactions of homo- and heterobinuclear cobalt carbonyls with metal carbonyl hydrides
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HMn(CO)5, HMo(CO)3Cp, and HFe(CO)2Cp (Cp = cyclopentadienyl) were found to react with Co2(CO)8 forming HCo(CO)4 and the corresponding mixed-metal carbonyl dimers. It was shown that HMo(CO)3Cp transferred the hydrogen atom to Co2(CO)8 and CoMn(CO)9 in reversible processes. The substituted hydride HMn(CO)4P-n-Bu3 and Co2(CO)8 afforded (CO)4CoMn(CO)4P-n-Bu3 which was characterized by elementary analysis and IR and mass spectroscopy. Its reaction with HMo(CO)3Cp gave HMn(CO)4P-n-Bu3 and CoMo(CO)7Cp. The attack of the hydrides took place in mixed-metal complexes exclusively on the cobalt atom. A mechanism in which the hydrides oxidatively add to a coordinatively unsaturated Co center formed by CO loss is proposed.
- Kovács, István,Sisak, Attila,Ungváry, Ferenc,Markó, László
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p. 1873 - 1877
(2008/10/08)
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- Alkylcobalt carbonyls. 9. Alkoxy-, silyloxy-, and hydroxy-substituted methyl- and acetylcobalt carbonyls. Reduction of formaldehyde to methanol by hydridocobalt tetracarbonyl
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(Alkoxymethyl)-, ((silyloxy)methyl)-, and (hydroxymethyl)cobalt and (alkoxyacetyl)-, ((silyloxy)acetyl)-, and (hydroxyacetyl)cobalt tetracarbonyls and phosphine-substituted derivatives were prepared. The interconversions of these compounds by carbonylatio
- Sisak, Attila,Sámpár-Szerencsés, Ella,Galamb, Vilmos,Németh, László,Ungváry, Ferenc,Pályi, Gyula
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p. 1096 - 1100
(2008/10/08)
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- Steric and Electronic Factors That Control Two-Electron Processes between Metal Carbonyl Cations and Anions
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Reactions of metal carbonyl cations (Mn(CO)6(+), Re(CO)6(+), Mn(CO)5PPh3(+), Mn(CO)4(PPh3)2(+), Mn(CO)5PEt3(+), Mn(CO)5PPh2Me(+), Re(CO)5PPh3(+), and CpFe(CO)3(+)) with metal carbonyl anions (Co(CO)3PPh3(-), Co(CO)4(-), Mn(CO)5(-), Mn(CO)4PPh3(-), Mn(CO)4PEt3(-), Mn(CO)4PPh2Me(-), Mn(CO)3(PPh3)2(-), CpFe(CO)2(-), Re(CO)5(-), and Re(CO)4PPh3(-)) are reported.Peak potentials are reported for all ions, and nucleophilicites (as measured by reaction with MeI) are reported for the anions.Reaction of any metal carbonyl cation with any metal carbonyl anion leads ultimately to binuclear products, which are the thermodynamic products.The binuclear products are formed by single-electron transfer.In over half of the reactions between metal carbonyl cations and anions, a two-electron change results in a new metal carbonyl cation and anion.The two-electron change may be considered mechanistically as a CO(2+) transfer with the more nucleophilic of the two anions retaining the CO(2+).The kinetic and thermodynamic driving forces and the suggested mechanism are examined.
- Zhen, Yueqian,Feighery, William G.,Lai, Chung-Kung,Atwood, Jim D.
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p. 7832 - 7837
(2007/10/02)
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- Photochemical Splitting of a Polar Metal-Metal Bond by Metal to Metal Charge Transfer Excitation of
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The polar metal-metal bond of I-Co-I(CO)4> was cleaved photochemically by metal to metall (Co-IAu+I) charge transfer excitation.Metallic gold, Ph3P and were formed as products. - Keywords: Photolysis, Metal-Metal Bond, Charge Transfer Excitation
- Vogler, Arnd,Kunkely, Horst
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p. 132 - 134
(2007/10/02)
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- DECARBOXYLATION OF ALKOXYCARBONYLCOBALT CARBONYLS
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Alkoxycarbonylcobalt tetracarbonyls undergo thermal decarboxylation between 25 and 90 deg C yielding up to 67percent CO2/Co atom; the decarboxylation is favoured by ligand excess (CO, PR3, NEt3).
- Bartik, Tamas,Kruemmling, Thomas,Marko, Laszlo,Palyi, Gyula
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p. 307 - 308
(2007/10/02)
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- Photochemistry of (M = Zn, Cd, Hg) induced by metal to metal charge transfer excitation
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The electronic absorption spectra of the complexes -1MIICo-1(CO)4> with M = Zn, Cd, and Hg display an intense long-wavelength band which is assignated to the allowed Σu+ -> Σg+ transition from a non-bonding ? to an antibonding ? orbital of the Co-M-Co moiety.This transition is shifted to higher energies and gains an increasing charge transfer (CT) contribution in changing M in the order M = Hg, Cd, and Zn.In a limiting description the ?n -> ?* transition can be regarded as a metal to metal (MM) CT transition from Co-1 to MII.MMCT excitation induced a photoredox reaction: -1-MII-Co-1(CO)4> -> M0 + 02(CO)8>.The quantum yields are Φ = 0.45 (λirr = 333 nm) for M = Hg and Φ = 0.03 (λirr = 313 nm) for Cd.
- Vogler, A.,Kunkely, H.
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- The mechanism of the formation of silyl enol ethers from hydrosilanes and organic carbonyl compounds in the presence of cobalt carbonyls. Kinetic investigation of some reaction steps
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The cleavage of isobutyrylcobalt tetracarbonyl with triethylsilane gives (triethylsilyl)cobalt tetracarbonyl, isobutyraldehyde, dicobalt octacarbonyl, and the corresponding unsaturated and saturated silyl ethers. Silyl enol ether was also formed, along wi
- Kovács, István,Sisak, Attila,Ungváry, Ferenc,Markó, László
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p. 1025 - 1028
(2008/10/08)
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- Metalloporphyrins with metal-metal bonds. Synthesis, characterization, and electrochemistry of (P)TlMn(CO)5, (P)TlCo(CO)4, and (P)TlM(CO)3Cp where M = Cr, Mo, and W. Crystal structure of [(2,3,7,8,12,13,17,18-octaethylporphinato)thallium(III)]pentacarbonylmanganese
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The synthesis, physicochemical properties, and electrochemistry of a new series of metal-metal σ-bonded thallium porphyrins are reported. The metalate ligands σ-bonded to the thallium octaethyl- or tetraphenylporphyrin complexes were Mn(CO)5, Co(CO)4, W(CO)3Cp, Mo(CO)3Cp, and Cr(CO)3Cp. Each neutral complex was characterized by 1H NMR, IR, and UV-visible spectroscopy, all of which suggested a single metal-metal covalent bond. The crystal structure of (OEP)TlMn(CO)5 was also solved (triclinic, P1, a = 12.467 (2) A?, b = 13.528 (2) A?, c = 15.088 (3) A?, α = 62.04 (2)°, β = 61.62 (2)°, γ = 69.53 (2)°, Z = 2, R(F) = 0.027, Rw(F) = 0.033, w = (σ2(I) + 0.04I)-1). The σ Tl-Mn bond length is 2.649 (1) A?. Electrochemistry and spectroelectrochemistry techniques were used to characterize each oxidized and reduced complex in methylene chloride containing 0.1 M tetrabutylammonium hexafluorophosphate as supporting electrolyte. Each complex underwent two oxidations, which were centered at the porphyrin π ring system. Unlike the case for metal-metal-σ-bonded indium porphyrins, no cleavage of the σ-bond occurs following the first oxidation; i.e., the generated radical cations are stable on the cyclic voltammetry time scale. The metal-metal-bonded compounds could also be reduced by two one-electron additions, but the generated anion radical stability was very low. The ultimate products of electroreduction were the free base porphyrin radical anion and a bis(thallium(I)) compound that was formed from a transient mono(thallium(I)) porphyrin complex.
- Guilard,Zrineh,Ferhat,Tabard,Mitaine,Swistak,Richard,Lecomte,Kadish
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p. 697 - 705
(2008/10/08)
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- Kinetic investigation of the cleavage of n-butyryl- or isobutyrylcobalt tetracarbonyl with hydridocobalt tetracarbonyl or dihydrogen
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The acylcobalt tetracarbonyls n-C3H7C(O)Co(CO)4 (1) and i-C3H7C(O)Co(CO)4 (2) react with H2 or HCo(CO)4 to yield n-butyraldehyde and isobutyraldehyde, respectively. Th
- Kovács, István,Ungváry, Ferenc,Markó, László
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p. 209 - 215
(2008/10/08)
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- Conversions of Germylidyne Tricobalt Clusters by Donor Ligands
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Upon heating with CO under pressure, the clusters Co3(CO)9(μ3-GeR) (1, R=Me, Ph, tBu) open to form the complexes (CO)4Co(RGe)Co2(CO)7 (2).With PPh3 either addition occurs to form Ph3P(CO)3Co(RGe)Co2(CO)6PPh3 (3, R=Me, Ph) or substitution to give Co3(CO)7(PPh3)2(μ3-Ge-tBu) (4).Organometal dimethylarsenides Cp(CO)3M-AsMe2 (5, M=Cr, Mo, W) react analogously for R=Me or Ph to yield the addition products 6 and for R=tBu to form the substitution products 7.Thermolyses of the organometal dimethylarsenide derivatives produce the metal-substituted clusters Co3(CO)9-μ4-Ge-MCp(CO)3 (9, M=Cr, Mo, W), the mixed metal clusters Co2M(CO)8Cp(μ3-GeR) (8, 12, M=Mo, W), and derivatives thereof, according to the conditions.
- Gusbeth, Petra,Vahrenkamp, Heinrich
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p. 1758 - 1769
(2007/10/02)
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- Kinetic investigation of the mixed-metal bimolecular reductive eliminations in the reactions of EtOC(O)CH2M(CO)n or EtOC(O)M(CO)n (M = Co, n = 4; M = Mn, n = 5) with HCo(CO)4 or HMn(CO)5
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The alkyl- and acylmetal carbonyls EtOC(O)CH2M(CO)n and EtOC(O)M(CO)n (M = Co, n = 4; M = Mn, n = 5) react with HCo(CO)4 or HMn(CO)5 to yield ethyl acetate or ethyl formate and the corresponding binuclear metal carbonyl. Kinetic experiments support a mechanism according to which the reaction between a coordinatively unsaturated alkyl- or acylmetal carbonyl (formed by CO loss) and the metal carbonyl hydride is rate determining. The rate of this bimolecular reductive elimination step varies strongly and unexpectedly in the mixed-metal systems.
- Kovács, István,Hoff, Carl D.,Ungváry, Ferenc,Markó, László
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p. 1347 - 1350
(2008/10/08)
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- Kinetics of the Reactions of (Ethoxycarbonyl)methylcobalt Tetracarbonyl with 13CO, Ph3P, HCo(CO)4, and H2. A Comparison of the Reactivities of RCo(CO)4 (R=CH2COOEt, COOEt, and H) Complexes
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The kinetics of the reactions of (ethoxycarbonyl)methylcobalt tetracarbonyl (1) with 13CO, Ph3P, HCo(CO)4, and H2 are consistent with initial reversible dissociation of EtOOCH2Co(CO)4 (1) to EtOOCCH2Co(CO)3 and CO.The alkylcobalt tricarbonyl then reacts competitively with the other reaction partner.The relative reactivities of 2 toward Ph3P, CO, HCo(CO)4, and H2 are 1.82, 1.0, 0.078, and 0.0006 at 25 deg C in n-heptane.The rate of 13CO substitution has also been measured for HCo(CO)4, Co2(CO)8, and (ethoxycarbonyl)cobalt tetracarbonyl (2).The half-life for HCo(CO)4 at -30 deg C is 45 s, t1/2 for EtOOCCH2Co(CO)4 at 15 deg C is 18.8 min, and t1/2 for EtOOCCo(CO)4 (2) at 15 deg C is 24.2 min.The complex 2 shows a slow 13CO incorporation into the acyl carbonyl group, t1/2 ca. 50 h at 28 deg C, presumably through an ethoxycobalt tetracarbonyl intermediate.The rate of 13CO exchange with Co2(CO)8 is not influenced by the presence of HCo(CO)4 at 0 deg C in n-octane, indicating that exchange of cobalt centers between HCo(CO)4 and Co2(CO)8 is slow compared to carbonyl exchange.
- Hoff, C. D.,Ungvary, F.,King, R. B.,Marko, L.
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p. 666 - 671
(2007/10/02)
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- Redox Reactions of Metal Carbonyls of Group 5A
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Redox reactions of V(CO)6 with -, -, 2-, or 5-C5H5)(CO)3>- (M = Cr, Mo, W), or Co(η5-C5H5)2 occur rapidly at 25 degC and lower in hydrocarbons; on the other hand, V(CO)6 is oxidized to V(η5-C5H5)(CO)4 by Mn(η5-C5H5)2 or Ni(η5-C5H5)2 and the two-electron oxidation of - to the - anion (X = Cl, Br, I, acetylacetonato), can be carried out using a number of oxidizing agents (HgII, CuII, CuI, AgI, or FeIII).
- Calderazzo, Fausto,Pampaloni, Guido
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p. 1249 - 1250
(2007/10/02)
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- Reaction of HCo(CO)4 and CO with styrene. Mechanism of (α-Phenylpropionyl)- and (β-Phenylpropionyl)cobalt tetracarbonyl formation
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Cobalt tetracarbonyl hydride and styrene react in the presence of carbon monoxide to form ethylbenzene and (α-phenylpropionyl)cobalt tetracarbonyl; both reactions are first order in HCo(CO)4 and PhCH=CH2 and independent of CO and Co2(CO)8 concentration. The kinetic data suggest a common radical pair intermediate for both reactions. (α-Phenylpropionyl)cobalt tetracarbonyl is not the final product of the reaction: it slowly decomposes into ethylbenzene, CO, and Co2(CO)8 and partly isomerizes into (β-phenylpropionyl) cobalt tetracarbonyl. Accordingly, among these acyl complexes the branched-chain isomer is the kineticly controlled product and the straight-chain isomer the thermodynamicly controlled product.
- Ungváry, Ferenc,Markó, László
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p. 1120 - 1125
(2008/10/08)
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