- Formation of a cluster-substituted cyclopentadienone from PhC2CCo3(CO)9. Crystal structure of Ph2C4C(O)2
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The cluster-substituted alkyne PhCCCCo3(CO)9 (1), obtained by a coupling reaction between BrCCo3(CO)9 and PhCCH, rearranges to give the cyclopentadienone Ph2C4C(O)2 (2).Alkyne 1 with Co2(CO)8 gives PhC2CCo3(CO)9 (3).Compound 2 was characterised by X-ray crystallography at 123 K.The structure is that of a symmetrically substituted cyclopentadienone with tricobaltcarbon cluster moieties substituted α to the carbonyl group and phenyl substituents in the β positions.Various findings suggest that the formation of 2 does not proceed via a meta llacycle.Electrochemical data shows that the clusters and the cyclopentadienone ring act as independent redox centres, indicating that there is no contiguous ?-interaction.
- Worth, Gillian H.,Robinson, Brian H.,Simpson, Jim
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- INSERTION REACTIONS OF 2-(ARYLAZO)ARYLTRICARBONYLCOBALT
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In contrast to o-metallated azobenzene-palladium complexes, 2-(phenylazo)-phenyltricarbonylcobalt is shown to undergo insertion of styrene, methyl acrylate, acrylonitrile and dimethyl fumarate as well as certain alkynes.New tricarbonylcobalt complexes derived from azotoluene, azoanisole and N-t-butylbenzaldimine and a new route to the azobenzene-derived complex are described.
- Janecki, Tomasz,Pauson, Peter L.,Pietrzykowski, Antoni
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- Synthese und Reaktionsverhalten von (η2-BrCCR)Co2(CO)6. Die Festk?rperstruktur von Pentacarbonyl-[μ-(1,2,3,4-η:1,4-η)-1,4-diphenyl-1,3-butadien-1,4- diyl]dicobalt
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The reaction of BrCCR (1a, R=nPr; 1b, R=nBu; 1c, R=SiMe3; 1d, R=Ph) with Co2(CO)8 (2) in a 1:1 molar ratio produces the hexacarbonyldicobalt complexes (η2-BrCCR)Co2(CO)6 (3a, R=nPr; 3b, R=nBu; 3c, R=SiMe3; 3d, R=Ph) in moderate yields. Apart from these complexes, pentametallic cobalt clusters of the general composition Co5(CO)12(CCR) (4a, R=nPr; 4b, R=nBu; 4c, R=SiMe3; 4d, R=Ph) are formed. Treatment of 1d with Na[Co(CO)4] (5) yields the butadi-1,3-yne complex [(η2-CCPh)Co2(CO)6]2 (6). A possible reaction mechanism for the formation of complexes 4 and 6 is described. The reaction of 4d with P(OiPr)3 (7) leads to a cluster degradation and the formation of Co2(CO)6[P(OiPr)3]2 (8). In contrast, on addition of HCCPh (9) to 4d the dicarbonyl(η4-tricarbonylcobaltacyclopentadiene) cobalt complex [η5-(PhC=CH-CH=CPh)Co(CO)3]Co(CO)2 (10) is obtained along with (η2-HCCPh)Co2(CO)6 (11). Complex 10 was characterized by single crystal X-ray crystallography. Homobimetallic 10 features a 5-membered PhC=CH-CH=CPh-Co(CO)3 ring, which is η5-coordinated to a Co(CO)2 fragment.
- Lang,Rheinwald,Lay,Zsolnai,Huttner
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- Synthesis, Coordination Study, and Catalytic Pauson-Khand Reactions of QuinoxP*(CO)4-μ-Alkyne Dicobalt Complexes
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The coordination of the P-stereogenic and sterically demanding bisphosphine QuinoxP* to μ-alkyne dicobalt hexacarbonyl complexes was studied experimentally and computationally. Whereas the coordination occurred exclusively in a chelating fashion, the diastereoselectivity was highly substrate dependent. However, it could be explained from the computed structure and energies of the different coordination modes. The fluxional behavior of these complexes was also studied computationally. Their performance as catalysts for the Pauson-Khand reaction was explored, and outstanding reactivity was observed. Although the asymmetric induction was low to moderate, the stereochemical outcome could be mechanistically rationalized. This report provides promising results in terms of reactivity and mechanistic understanding for further developments of highly active chiral catalysts for intermolecular Pauson-Khand reactions.
- Gar?on, Martí,Cabré, Albert,Verdaguer, Xavier,Riera, Antoni
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- Phosphorus-Sulfur Bond Cleavage at a Mixed-metal Centre; Reaction of 5-C5H5)> with PPh2(SPh)
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The bimetallic cobalt-molybdenum complex 5-C5H5)> reacted with phenylacetylene in benzene to give the bimetallic alkyne-bridged complex 5-C5H5)> 1 as the major product and the trimetallic alkylidyne-capped complex 3-CCH2Ph)(CO)8(η5=C5H5)> 2 as the minor product.Reaction of 1 with PPh2(SPh) resulted in substitution of a carbonyl group on the cobalt atom to give (OC)2Co(μ-PhCCH)Mo(CO)2(η5-C5H5)> 3.Thermolysis of 3 in refluxing toluene afforded, as the major product, the complex 5-C5H5)(OC)Mo(μ-PPh2CH=CPh)(μ-SPh)Co(CO)2> 4, in which the unsymmetrical alkyne in 3 has been incorporated into a four-membered metallacycle, , such that the phenyl substituent is positioned on the carbon atom remote from the phosphide group.The related complex 5-C5H5)(OC)Mo(μ-PPh2CH=CPh)(μ-SPh)Co(CO)(PPh3)> 5, in which one of the carbonyl groups on the cobalt atom in 4 has been substituted by a triphenylphosphine ligand, has also been isolated as a minor product from this reaction.Conversion of 4 into 5 has been achieved separately by reaction of 4 with PPh3.Similarly, reaction of PPh2(SPh) with 4 yields a related compound 5-C5H5)(OC)Mo(μ-PPh2CH=CPh)(μ-SPh)Co(CO)> 6, in which the same carbonyl group on the cobalt atom has been substituted by PPh2(SPh).Single-crystal X-ray diffraction studies have been performed on complexes 2, 4 and 6.
- Ingham, Scott L.,Mays, Martin J.,Raithby, Paul R.,Solan Gregory A.,Sundavadra, Bharat V.,et al.
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- Carbamate as an accelerating group in intermolecular Pauson-Khand reaction
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The Pauson-Khand reaction (PKR) is a powerful means for the construction of cyclopentenones. However, its applications have been limited to the intramolecular version of this reaction because poor yield and regioselectivity are often the major problems in intermolecular PKR. Here we describe that a carbamate moiety in alkene substrate accelerates this intermolecular PKR. The reaction of N-4-dimethylaminophenyl O-allyl carbamate with alkyne-cobalt complex gave cyclopentenones in high yield (up to 90%) and regioselectivity (>9:1).
- Asano, Shota,Itto-Nakama, Kaori,Arimoto, Hirokazu
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supporting information
(2020/05/05)
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- Unraveling factors leading to efficient norbornadiene-quadricyclane molecular solar-thermal energy storage systems
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Developing norbornadiene-quadricyclane (NBD-QC) systems for molecular solar-thermal (MOST) energy storage is often a process of trial and error. By studying a series of norbornadienes (NBD-R2) doubly substituted at the C7-position with R = H, M
- Jorner, Kjell,Dreos, Ambra,Emanuelsson, Rikard,El Bakouri, Ouissam,Galván, Ignacio Fdez.,B?rjesson, Karl,Feixas, Ferran,Lindh, Roland,Zietz, Burkhard,Moth-Poulsen, Kasper,Ottosson, Henrik
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supporting information
p. 12369 - 12378
(2017/07/10)
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- The Pauson-Khand reaction of medium sized trans-cycloalkenes
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Medium sized trans-cycloalkenes are unusually reactive in the intermolecular Pauson-Khand reaction (PKR) with regard to typical monocyclic alkenes. This is due to the ring strain imparted by the E stereochemistry. The PKR of these alkenes offers a modular, regioselective and straightforward entry to trans fused [n.3.0] bicyclic scaffolds (n = 6-8). The Royal Society of Chemistry.
- Lledo, Agusti,Fuster, Aida,Reves, Marc,Verdaguer, Xavier,Riera, Antoni
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supporting information
p. 3055 - 3057
(2013/05/09)
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- Pauson-Khand reactions in a photochemical flow microreactor
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Pauson-Khand reactions were achieved at ambient temperature without any additive using a photochemical flow microreactor. The efficiency of the reaction was better than that in a conventional batch reactor, and the reaction could be operated continuously for 1 h.
- Asano, Keisuke,Uesugi, Yuki,Yoshida, Jun-Ichi
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supporting information
p. 2398 - 2401
(2013/06/27)
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- The photochemistry of (μ2-RC2H)Co2(CO)6 species (R=H or C6H5), important intermediates in the Pauson-Khand reaction
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The photochemistry of (μ2-RC2H)Co2(CO)6 (R=H or C6H5) has been investigated by both time-resolved and steady-state techniques. Pulsed excitation in cyclohexane solution with λexc
- Draper, Sylvia M.,Long, Conor,Myers, Bronagh M.
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p. 195 - 199
(2007/10/03)
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- Reaction of cobalt tetracarbonyl hydride with phenylacetylene
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In C6H6 or hexane at room temperature, under an atmosphere of CO, excess HCo(CO)4 reacts with phenylacetylene to give ethylbenzene and 2-phenylpropanal, the same products that result from the similar reaction of styrene. T
- Bockman, T. Michael,Garst, John F.,Ungvary, Ferenc
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- Carbonylative cyclization of alkynes using cobalt carbonyl species prepared via reduction of CoBr2 with Zn under a carbon monoxide atmosphere
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Alkyne-Co2(CO)6 complexes prepared in situ using CoBr2, Zn, and CO give the corresponding cycloentenones or cyclopentadienones on heating in toluene or in CH2Cl2 at 25°C in the presence of DMSO or amines.
- Rajesh, Thotapally,Periasamy, Mariappan
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p. 5709 - 5712
(2008/10/08)
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- Synthesis and structure of Co3C clusters with alkyne functionality
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Tricobalt carbon clusters with alkyne functionality R(C≡C)nCCo3(CO)9 (R = Me3Si, n = 1, 2; R = Ph, (η5-C5H5)Fe(η5-C 5H4) (Fc), and H, n = 1) have
- Worth, Gillian H.,Robinson, Brian H.,Simpson, Jim
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p. 501 - 513
(2008/10/08)
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- Alkinyl-substituierte Chlorsilane als Clusterbausteine
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The reaction of phenylethynyl-substituted chlorosilanes with dicobaltoctacarbonyl is discussed.Co2(CO)8 (II) yields selectively with (R)(PhCC)Si(H)(Cl) (R = Me: I; R = CCPh: V) (R)2-CCPh)Co2(CO)6>Si(H)(Cl) (R = Me: III; R = CCPh: VI), in which the phenylethynyl group is η2 side-on co-ordinated to "Co2(CO)6".III affords with further Co2(CO)8 under oxidative addition (Me)2-CCPh)Co2(CO)6>Si(Cl) (IV); IV may also be obtained directly by the reaction of I with 1.5 equivalents of II.VI contains a non-coordinated CCPh group and yields with one equivalent of II the tetranuclear complex 2-CCPh)Co2(CO)6>2Si(H)(Cl) (VII) in which the two CCPh ligands form sterically-hindered carbon-cobalt tetrahedrane cluster units.Compounds VIII and X show the same reaction behaviour as I and V: (R)(PhCC)Si(Cl)2 (R = Ph:VIII; R = H:X) reacts with one equivalent of II to yield in the first step (R)2-CCPh)Co2(CO)6>Si(Cl)2 (R = Ph:IX; R = H:XI).Addition of 0.5 parts of II to XI affords in high yields complex 2-CCPh)Co2(CO)6>Si(Cl)2 (XII).In a similar manner, compound (Me)(PhCC)Si(H)2 (XIII) yields with one equivalent of II the dinuclear complex (Me)2-CCPh)Co2(CO)6>Si(H)2 (XIV) which slowly decompose to form oligomeric compounds as well as (η2-PhCCH)Co2(CO)6 (XV).All new compounds were characterized by analytical and spectroscopic data (IR, 1H, 13C NMR, MS), and (Me)2-CCPh)Co2(CO)6>Si(Cl) (IV) by X-ray analysis.
- Lang, Heinrich,Lay, Uwe,Zsolnai, Laszlo
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p. 377 - 387
(2007/10/02)
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- Zur Umsetzung von Chlor-Methyl-Phenylethinyl-Silan mit Octacarbonyldicobalt; Reaktivitaetsstudien an 2-CCPh)Co2(CO)6>(Me)Si(H)(Cl)
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(Me)(PhCC)Si(H)(Cl) (I) reacts selectively with Co2(CO)8 (II) to yield the η2-side-on coordinated compound (Me)(H)(Cl)Si2-CCPh)Co2(CO)6> (III).Treatment of III with 0.5 mol of Co2(CO)8 yields the complex (Me)(Cl)Si(ηsup
- Lang, Heinrich,Lay, Uwe
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- METHYLENECYCLOPROPANE IN THE CYCLOADDITION REACTION WITH DICOBALT-HEXACARBONYL COMPLEXES OF ACETYLENES
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The ability of methylencyclopropane to undergo -cycloaddition reactions with dicobalt-hexacarbonyl complexes of alkynes with formation of spiro-heptenone derivatives has been revealed for the first time.The conditions for carrying out this rea
- Kireev, S. L.,Smit, V. A.,Nefedov, O. M.
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p. 1896 - 1903
(2007/10/02)
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- The effect of ultrasound and of phosphine and phosphine-oxides on the Khand reaction
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Ultrasonic irradation allows the Khand reaction to be conducted rapidly at low temperatures.Addition of phosphine oxides to the reaction mixture significantly increases yields in most cases.
- Billington, David C.,Helps, I. Malcolm,Pauson, Peter L.,Thomson, William,Willison, Debra
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p. 233 - 242
(2007/10/02)
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- THE REACTIVITY OF ACETYLENES COORDINATED TO COBALT III. REACTION OF THE BUTENE-2-OLIDE-4 COMPLEXES, (C4O2R1, R2)Co2(CO)7 WITH ACETYLENES; FORMATION OF NEW TYPES OF ORGANIC LIGANDS
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The "lactone" complexes, (C4O2R1,R2)Co2(CO)7, (μ2-carbonyl)2-spiro-(2,3-substituted-2-butene-4-olide-4-ylidene)>bis(tricarbonyl-cobalt)(Co-Co) derivatives, were found to reacti with acetylenes (R3C2
- Varadi, Gyula,Horvath, Istvan T.,Palyi, Gyula,Marko, Laszlo,Slovokhotov, Yurii L.,Struchkov, Yurii T.
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p. 119 - 130
(2007/10/02)
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- The preparation of some cobalt carbonyl complexes containing ligand-bridged metal atoms
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The complexes LCo2(CO)6, LCo2(CO)4HCCC6H5, ffarsCo2(CO)5, CH3CCo3(CO)7ffars, and Co4(CO)8(ffars)2 are
- Crow,Cullen
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p. 2165 - 2170
(2008/10/08)
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