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Gu Y, Lin Y, Jiang H, Li B, Wu C, Liu J, Liu J, Wang Y, Cui D, Tang T. Mechanism for Coordination Quasi-Depolymerization of Polydiolefins with Cp 2ZrHCl. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c01000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yang Gu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
- Hisense Ronshen (Guangdong) Refrigerator Co., LTD., Foshan 528303, China
| | - Yichao Lin
- School of Safety Engineering, China University of Mining and Technology, Xuzhou 221116, China
| | - Hanqing Jiang
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Bingwen Li
- Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China
| | - Chunji Wu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Jie Liu
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Jingyao Liu
- Institute of Theoretical Chemistry, Jilin University, Changchun 130023, China
| | - Yanhui Wang
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Dongmei Cui
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Tao Tang
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
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2
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Basta R, Arif AM, Ernst RD. Synthetic and structural studies of coupling products of diimines with open half-open titanocenes and zirconocenes. Polyhedron 2022. [DOI: 10.1016/j.poly.2022.115993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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3
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Mandal U, Ghiviriga I, Abboud KA, Lester DW, Veige AS. Double Tethered Metallacyclobutane Catalyst for Cyclic Polymer Synthesis. J Am Chem Soc 2021; 143:17276-17283. [PMID: 34618432 DOI: 10.1021/jacs.1c08806] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This work outlines an approach to creating a catalyst for cyclic polymer synthesis using readily available materials in only one or two steps. Combining commercially available molybdenum-alkylidene 1 with two equivalents of ene-ol proligand 2 rapidly produces, in quantitative yield (1H NMR spectroscopy), the double tethered metallacyclobutane complex 3. Characterized by variable temperature NMR studies and nuclear Overhauser effect spectroscopy (NOESY) experiments, complex 3 exhibits fluxional behavior in solution. Determined by single crystal X-ray diffraction, the solid-state structure of complex 3 reveals metrical parameters indicating that the metallacyclobutane is not predicted to undergo rapid retro-cycloaddition. However, complex 3 is a precatalyst for the polymerization of norbornene to produce cyclic polynorbornene. An NMR spectrum of a test polymerization indicates that only a small fraction of the precatalyst is activated upon exposure to monomer. Quantifying the active catalyst is possible by measuring vinyl resonances that appear in the 1H NMR spectrum. The vinyl resonances are attributable to the release of one of the tethers upon norbornene addition. Confirmation of the polymer cyclic topology comes from gel permeation chromatography (GPC), dynamic light scattering (DLS), and intrinsic viscosity (η) measurements. The double tethered metallacyclobutane complex is a novel design for catalytic cyclic polymer synthesis. The synthetic approach suggests that catalyst tuning is possible by a choice of the commercial alkylidene and alteration of the ene-ol proligand.
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Affiliation(s)
- Ushnish Mandal
- Department of Chemistry, Center for Catalysis, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States
| | - Ion Ghiviriga
- Department of Chemistry, Center for NMR Spectroscopy, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States
| | - Khalil A Abboud
- Department of Chemistry, Center for Catalysis, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States
| | - Daniel W Lester
- Polymer Characterization Research Technology Platform, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Adam S Veige
- Department of Chemistry, Center for Catalysis, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, United States
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4
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Gordon CP, Raynaud C, Andersen RA, Copéret C, Eisenstein O. Carbon-13 NMR Chemical Shift: A Descriptor for Electronic Structure and Reactivity of Organometallic Compounds. Acc Chem Res 2019; 52:2278-2289. [PMID: 31339693 DOI: 10.1021/acs.accounts.9b00225] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Metal-bonded carbon atoms in metal-alkyl, metal-carbene/alkylidene, and metal-carbyne/alkylidyne species often show significantly more deshielded isotropic chemical shifts than their organic counterparts (alkanes, alkenes, and alkynes). While isotropic chemical shift is universally used to characterize a chemical compound in solution, it is an average value of the three principal components of the chemical shift tensor (δ11 > δ22 > δ33). The tensor components, which are accessible by solid-state NMR spectroscopy, can provide detailed information about the electronic structure (frontier molecular orbitals) at the observed nuclei. This information can be accessed in detail by quantum chemical calculations, most notably by an analysis of the paramagnetic contribution to the NMR shielding tensor. The paramagnetic term mainly results from the coupling of occupied and empty molecular orbitals close in energy-the frontier molecular orbitals-under the effect of the external magnetic field (B0). In organometallic compounds, a large deshielding of the isotropic carbon-13 chemical shift of the metal-bonded carbon atom is commonly related to the coupling between the occupied σM-C orbital and low-lying vacant orbitals of πM═C* character. The deshielding at the α-carbon hence probes the extent of σM-C and πM═C* interactions. This molecular orbital view readily explains the strong deshielding and large anisotropy (evidenced by the span Ω = δ11 - δ33) observed in metal alkylidenes and alkylidynes (200 < δiso < 400 ppm). Fischer carbenes are generally more deshielded than Schrock or Grubbs alkylidenes due to their low-lying πM═C* orbital. Chemical shift hence shows their higher electrophilic character, connecting NMR spectroscopy to reactivity patterns. Similarly, the α-carbon of metal-alkyls display deshielded chemical shifts in specific coordination environments. This deshielding, which is often prominently pronounced for cationic species, indicates the presence of partial π-bond character in the metal-carbon bond, making these bonds topologically equivalent to alkylidene π-bonds. The π-character in metal-alkyl bonds favors (i) α-H abstraction processes in metal bis-alkyl compounds yielding metal alkylidenes, (ii) [2 + 2]-retrocyclization of metallacyclobutanes that participate in olefin metathesis, (iii) olefin insertion in cationic metal alkyls thus explaining polymerization activity trends and the importance of α-H agostic interactions, and (iv) C-H bond activation on metal-alkyls via σ-bond metathesis. The presence of π-character in the metal-carbon bonds involved in these processes rationalizes the parallel reactivity patterns of metal-alkyls toward olefin insertion and σ-bond metathesis and the fact that σ-bond metathesis, olefin insertion, and olefin metathesis are commonly observed with metal atoms in the same ligand field. Because of the similarities in the frontier molecular orbitals involved in these processes, these reactions can be viewed as isolobal. This explains why certain fragments, such as bent metallocenes (d0 Cp2M) or T-shaped L3M, are ubiquitous in these reactions.
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Affiliation(s)
- Christopher P. Gordon
- ETH Zürich, Department of Chemistry and Applied Biosciences, Vladimir Prelog Weg. 1-5, CH-8093 Zürich, Switzerland
| | | | - Richard A. Andersen
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Christophe Copéret
- ETH Zürich, Department of Chemistry and Applied Biosciences, Vladimir Prelog Weg. 1-5, CH-8093 Zürich, Switzerland
| | - Odile Eisenstein
- ICGM, Université Montpellier, CNRS, ENSCM, 34095 Montpellier, France
- Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, P.O.
Box 1033, Blindern, 0315 Oslo, Norway
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5
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Chen J, Yassin N, Gunasekara T, Norton JR, Rauch M. Insertion of Isonitriles into the M-C Bonds of Group 4 Dialkyl Complexes. J Am Chem Soc 2018; 140:8980-8989. [PMID: 29907010 DOI: 10.1021/jacs.8b05377] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The 2,3-dimethylbutadiene complexes of Group 4 metals with constrained geometry (cg) ligands have been prepared and found to adopt a supine orientation with σ2,π bonding. Treatment of cgTi(2,3-dimethylbutadiene) (1-Ti) with tBuNC leads to the formation of a titana-aziridine (3) with a coordinated cyclopentenimine that arises from the formal [4+1] addition of the diene to the isonitrile. In contrast, the reactions of cgZr(2,3-dimethylbutadiene) (1-Zr) or cgHf(2,3-dimethylbutadiene) (1-Hf) with 2 equiv of tBuNC or XyNC proceeded in a more sophisticated manner to yield unsymmetrical 2,5-diazametallacyclopentane derivatives (4, 6-Zr, and 6-Hf) or symmetrical 2,5-diazametallacyclopentene complexes (7-Zr and 7-Hf). The unsymmetrical products contain coordinated cyclopropanes; the strength of the interaction is measured by the reduction in the 1 JCC of the C-C bond that is coordinated. A detailed mechanistic analysis has been possible with the related cgM(Me)2 (M = Ti and Hf) complexes. The first insertion is too fast to monitor, but allows complete conversion to an alkyl iminoacyl intermediate. The second isonitrile (RNC) may react with that intermediate by either of two different mechanisms, reductive elimination and coordination/insertion. In the first mechanism (Ti), rate-determining C-C coupling gives a titana-aziridine, followed by fast coordination of the isonitrile. In the second mechanism (Hf), coordination is the slow step; insertion to form a bis(iminoacyl) Hf complex is rapid.
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Affiliation(s)
- Jiawei Chen
- Department of Chemistry , Columbia University , 3000 Broadway , New York , New York 10027 , United States
| | - Nadine Yassin
- Department of Chemistry , Barnard College , 3009 Broadway , New York , New York 10027 , United States
| | - Thilina Gunasekara
- Department of Chemistry , Columbia University , 3000 Broadway , New York , New York 10027 , United States
| | - Jack R Norton
- Department of Chemistry , Columbia University , 3000 Broadway , New York , New York 10027 , United States
| | - Michael Rauch
- Department of Chemistry , Columbia University , 3000 Broadway , New York , New York 10027 , United States
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6
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Gordon C, Yamamoto K, Liao WC, Allouche F, Andersen RA, Copéret C, Raynaud C, Eisenstein O. Metathesis Activity Encoded in the Metallacyclobutane Carbon-13 NMR Chemical Shift Tensors. ACS CENTRAL SCIENCE 2017; 3:759-768. [PMID: 28776018 PMCID: PMC5532720 DOI: 10.1021/acscentsci.7b00174] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Indexed: 06/02/2023]
Abstract
Metallacyclobutanes are an important class of organometallic intermediates, due to their role in olefin metathesis. They can have either planar or puckered rings associated with characteristic chemical and physical properties. Metathesis active metallacyclobutanes have short M-Cα/α' and M···Cβ distances, long Cα/α'-Cβ bond length, and isotropic 13C chemical shifts for both early d0 and late d4 transition metal compounds for the α- and β-carbons appearing at ca. 100 and 0 ppm, respectively. Metallacyclobutanes that do not show metathesis activity have 13C chemical shifts of the α- and β-carbons at typically 40 and 30 ppm, respectively, for d0 systems, with upfield shifts to ca. -30 ppm for the α-carbon of metallacycles with higher d n electron counts (n = 2 and 6). Measurements of the chemical shift tensor by solid-state NMR combined with an orbital (natural chemical shift, NCS) analysis of its principal components (δ11 ≥ δ22 ≥ δ33) with two-component calculations show that the specific chemical shift of metathesis active metallacyclobutanes originates from a low-lying empty orbital lying in the plane of the metallacyclobutane with local π*(M-Cα/α') character. Thus, in the metathesis active metallacyclobutanes, the α-carbons retain some residual alkylidene character, while their β-carbon is shielded, especially in the direction perpendicular to the ring. Overall, the chemical shift tensors directly provide information on the predictive value about the ability of metallacyclobutanes to be olefin metathesis intermediates.
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Affiliation(s)
- Christopher
P. Gordon
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, 8093, Zürich, Switzerland
| | - Keishi Yamamoto
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, 8093, Zürich, Switzerland
| | - Wei-Chih Liao
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, 8093, Zürich, Switzerland
| | - Florian Allouche
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, 8093, Zürich, Switzerland
| | - Richard A. Andersen
- Department
of Chemistry, University of California, Berkeley, California 94720, United States
| | - Christophe Copéret
- Department
of Chemistry and Applied Biosciences, ETH
Zürich, Vladimir Prelog Weg 1-5, 8093, Zürich, Switzerland
| | - Christophe Raynaud
- Institut
Charles
Gerhardt, UMR 5253 CNRS-Université de Montpellier, Université de Montpellier, 34095 Montpellier, France
| | - Odile Eisenstein
- Institut
Charles
Gerhardt, UMR 5253 CNRS-Université de Montpellier, Université de Montpellier, 34095 Montpellier, France
- Centre
for Theoretical and Computational Chemistry (CTCC), Department of
Chemistry, University of Oslo, P.O. Box 1033, Blindern, 0315 Oslo, Norway
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7
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Affiliation(s)
- Benjamin G. Harvey
- US Navy Naval Air Warfare Center Weapons Division (NAWCWD) Research Department Chemistry Division 93555 China Lake California USA
| | - Richard D. Ernst
- Inorganic Chemistry Department of Chemistry University of Utah 84112 Salt Lake City Utah USA
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8
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Ramful CD, Konway ZE, Boudreau S, Areephong J, Robertson KN, Ylijoki KE. Confirmation of the pentadienyl/alkyne [5 + 2] cycloaddition reactivity of the Cp*Co(η5-1,2,5-trimethylpentadienyl)+ complex. J Organomet Chem 2016. [DOI: 10.1016/j.jorganchem.2016.10.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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9
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Ylijoki KEO, Kirk AD, Böcklein S, Witherell RD, Stryker JM. Cobalt-Mediated η5-Pentadienyl/Alkyne [5 + 2] Cycloaddition Reactions: Substitution Effects, Bicyclic Synthesis, and Photochemical η4-Cycloheptadiene Demetalation. Organometallics 2015. [DOI: 10.1021/acs.organomet.5b00346] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kai E. O. Ylijoki
- Department of Chemistry, Saint Mary’s University, Halifax, Nova Scotia, Canada B3H 3C3
| | - Andrew D. Kirk
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
| | - Sebastian Böcklein
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
| | - Ross D. Witherell
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
| | - Jeffrey M. Stryker
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
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10
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Remya PR, Suresh CH. Hypercoordinate β-carbon in Grubbs and Schrock olefin metathesis metallacycles. Dalton Trans 2015; 44:17660-72. [DOI: 10.1039/c5dt02801a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
From the analysis of structural, bond order, electron density and 13C NMR data of a large variety of ruthenacyclobutanes and tungstenacyclobutanes, we show that the Cβ of the metallacycle is pentacoordinate.
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Affiliation(s)
- Premaja R. Remya
- Chemical Sciences and Technology Division
- CSIR-National Institute for Interdisciplinary Science and Technology
- Trivandrum 695 019
- India
- Academy of Scientific & Innovative Research
| | - Cherumuttathu H. Suresh
- Chemical Sciences and Technology Division
- CSIR-National Institute for Interdisciplinary Science and Technology
- Trivandrum 695 019
- India
- Academy of Scientific & Innovative Research
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11
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Etienne M, Weller AS. Intramolecular C–C agostic complexes: C–C sigma interactions by another name. Chem Soc Rev 2014; 43:242-59. [DOI: 10.1039/c3cs60295h] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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12
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The influence of phosphine cone angle on the synthesis and structures of [Rh(PR3)(Binor–S)]+ complexes that show C–C sigma interactions. J Organomet Chem 2013. [DOI: 10.1016/j.jorganchem.2012.09.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Ylijoki KEO, Stryker JM. [5 + 2] Cycloaddition Reactions in Organic and Natural Product Synthesis. Chem Rev 2012; 113:2244-66. [PMID: 23153111 DOI: 10.1021/cr300087g] [Citation(s) in RCA: 310] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Kai E. O. Ylijoki
- Department of Chemistry, University
of Alberta, Edmonton,
Alberta T6G 2G2, Canada
| | - Jeffrey M. Stryker
- Department of Chemistry, University
of Alberta, Edmonton,
Alberta T6G 2G2, Canada
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14
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Frazier BA, Wolczanski PT, Keresztes I, DeBeer S, Lobkovsky EB, Pierpont AW, Cundari TR. Synthetic approaches to (smif)2Ti (smif = 1,3-di-(2-pyridyl)-2-azaallyl) reveal redox non-innocence and C-C bond-formation. Inorg Chem 2012; 51:8177-86. [PMID: 22830452 DOI: 10.1021/ic300590t] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Attempted syntheses of (smif)(2)Ti (smif =1,3-di-(2-pyridyl)-2-azaallyl) based on metatheses of TiCl(n)L(m) (n = 2-4) with M(smif) (M = Li, Na), in the presence of a reducing agent (Na/Hg) when necessary, failed, but several apparent Ti(II) species were identified by X-ray crystallography and multidimensional NMR spectroscopy: (smif){Li(smif-smif)}Ti (1, X-ray), [(smif)Ti](2)(μ-κ(3),κ(3)-N,N(py)(2)-smif,smif) (2), (smif)Ti(κ(3)-N,N(py)(2)-smif,(smif)H) (3), and (smif)Ti(dpma) (4, dpma = di-2-pyridylmethyl-amide). NMR spectroscopy and K-edge XAS showed that each compound possesses ligands that are redox noninnnocent, such that d(1) Ti(III) centers AF-couple to ligand radicals: (smif){Li(smif-smif)(2-)}Ti(III) (1), [(smif(2-))Ti(III)](2)(μ-κ(3),κ(3)-N,N(py)(2)-smif,smif) (2), [(smif(2-))Ti(III)](κ(3)-N,N(py)(2)-smif,(smif)H) (3), and (smif(2-))Ti(III)(dpma) (4). The instability of (smif)(2)Ti relative to its C-C coupled dimer, 2, is rationalized via the complementary nature of the amide and smif radical dianion ligands, which are also common to 3 and 4. Calculations support this contention.
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Affiliation(s)
- Brenda A Frazier
- Department of Chemistry & Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, United States
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15
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Ylijoki KEO, Budzelaar PHM, Stryker JM. A Density Functional Theory Investigation of the Cobalt-Mediated η5-Pentadienyl/Alkyne [5+2] Cycloaddition Reaction: Mechanistic Insight and Substituent Effects. Chemistry 2012; 18:9894-900. [DOI: 10.1002/chem.201200319] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 04/27/2012] [Indexed: 11/09/2022]
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16
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Hasanayn F, Achord P, Braunstein P, Magnier HJ, Krogh-Jespersen K, Goldman AS. Theoretical Structure–Reactivity Study of Ethylene Insertion into Nickel–Alkyl Bonds. A Kinetically Significant and Unanticipated Role of trans Influence in Determining Agostic Bond Strengths. Organometallics 2012. [DOI: 10.1021/om300001n] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Faraj Hasanayn
- Department
of Chemistry, The American University of Beirut, Beirut, Lebanon
| | - Patrick Achord
- Department of
Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick,
New Jersey 08903, United States
| | - Pierre Braunstein
- Laboratoire de Chimie de Coordination, Institut de Chimie (UMR 7177 CNRS), Université de Strasbourg, F-67081
Strasbourg Cédex, France
| | | | - Karsten Krogh-Jespersen
- Department of
Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick,
New Jersey 08903, United States
| | - Alan S. Goldman
- Department of
Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, New Brunswick,
New Jersey 08903, United States
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18
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Escudié Y, Dinoi C, Allen O, Vendier L, Etienne M. An Unsymmetrical bis CC Agostic Heterobimetallic Lithium Yttrium Complex. Angew Chem Int Ed Engl 2012; 51:2461-4. [DOI: 10.1002/anie.201107870] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Revised: 12/20/2011] [Indexed: 11/08/2022]
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19
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Escudié Y, Dinoi C, Allen O, Vendier L, Etienne M. An Unsymmetrical bis CC Agostic Heterobimetallic Lithium Yttrium Complex. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201107870] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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20
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Montag M, Efremenko I, Diskin-Posner Y, Ben-David Y, Martin JML, Milstein D. Exclusive C–C Oxidative Addition in a Rhodium Thiophosphoryl Pincer Complex and Computational Evidence for an η3-C–C–H Agostic Intermediate. Organometallics 2011. [DOI: 10.1021/om201205y] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Michael Montag
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76000, Israel
| | - Irena Efremenko
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76000, Israel
| | - Yael Diskin-Posner
- Department of Chemical Research
Support, Weizmann Institute of Science,
Rehovot 76000, Israel
| | - Yehoshoa Ben-David
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76000, Israel
| | - Jan M. L. Martin
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76000, Israel
| | - David Milstein
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76000, Israel
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21
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Chaplin AB, Green JC, Weller AS. C-C activation in the solid state in an organometallic σ-complex. J Am Chem Soc 2011; 133:13162-8. [PMID: 21736363 DOI: 10.1021/ja2047599] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Herein is reported the synthesis, by a solid-state reaction from [Ir(NBD)(2)(P(i)Pr(3))][BAr(F)(4)], of the first example of a C-C σ-complex with iridium, [Ir(BINOR-S)(P(i)Pr(3))][BAr(F)(4)]. This compound is unique in that in the solid state it undergoes reversible activation of the C-C single bond that interacts with the metal center, establishing a temperature-dependent equilibrium between Ir(III) C-C σ/Ir(V) bis-alkyl complexes. This process has been interrogated by variable-temperature X-ray diffraction, NMR spectroscopy, and DFT calculations.
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Affiliation(s)
- Adrian B Chaplin
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, UK
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22
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Wenzel AG, Blake G, VanderVelde DG, Grubbs RH. Characterization and dynamics of substituted ruthenacyclobutanes relevant to the olefin cross-metathesis reaction. J Am Chem Soc 2011; 133:6429-39. [PMID: 21452876 PMCID: PMC3083245 DOI: 10.1021/ja2009746] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The reaction of the phosphonium alkylidene [(H(2)IMes)RuCl(2)=CHP(Cy)(3))](+) BF(4)(-) with propene, 1-butene, and 1-hexene at -45 °C affords various substituted, metathesis-active ruthenacycles. These metallacycles were found to equilibrate over extended reaction times in response to decreases in ethylene concentrations, which favored increased populations of α-monosubstituted and α,α'-disubstituted (both cis and trans) ruthenacycles. On an NMR time scale, rapid chemical exchange was found to preferentially occur between the β-hydrogens of the cis and trans stereoisomers prior to olefin exchange. Exchange on an NMR time scale was also observed between the α- and β-methylene groups of the monosubstituted ruthenacycle (H(2)IMes)Cl(2)Ru(CHRCH(2)CH(2)) (R = CH(3), CH(2)CH(3), (CH(2))(3)CH(3)). EXSY NMR experiments at -87 °C were used to determine the activation energies for both of these exchange processes. In addition, new methods have been developed for the direct preparation of metathesis-active ruthenacyclobutanes via the protonolysis of dichloro(1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene)(benzylidene) bis(pyridine)ruthenium(II) and its 3-bromopyridine analogue. Using either trifluoroacetic acid or silica-bound toluenesulfonic acid as the proton source, the ethylene-derived ruthenacyclobutane (H(2)IMes)Cl(2)Ru(CH(2)CH(2)CH(2)) was observed in up to 98% yield via NMR at -40 °C. On the basis of these studies, mechanisms accounting for the positional and stereochemical exchange within ruthenacyclobutanes are proposed, as well as the implications of these dynamics toward olefin metathesis catalyst and reaction design are described.
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Affiliation(s)
- Anna G Wenzel
- Joint Science Department, Claremont McKenna, Pitzer, and Scripps Colleges, Claremont, California 91711, USA.
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Ylijoki KEO, Witherell RD, Kirk AD, Böcklein S, Lofstrand VA, McDonald R, Ferguson MJ, Stryker JM. Synthesis, Structure, and Reactivity of Alkyl-Substituted Half-Sandwich η5-Pentadienyl Complexes of Cobalt. Organometallics 2009. [DOI: 10.1021/om900754h] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kai E. O. Ylijoki
- Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2 Canada
| | - Ross D. Witherell
- Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2 Canada
| | - Andrew D. Kirk
- Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2 Canada
| | - Sebastian Böcklein
- Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2 Canada
| | - Verner A. Lofstrand
- Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2 Canada
| | - Robert McDonald
- Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2 Canada
| | - Michael J. Ferguson
- Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2 Canada
| | - Jeffrey M. Stryker
- Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2 Canada
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Scheins S, Messerschmidt M, Gembicky M, Pitak M, Volkov A, Coppens P, Harvey BG, Turpin GC, Arif AM, Ernst RD. Charge Density Analysis of the (C−C)→Ti Agostic Interactions in a Titanacyclobutane Complex. J Am Chem Soc 2009; 131:6154-60. [DOI: 10.1021/ja807649k] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Stephan Scheins
- Department of Chemistry, University of New York at Buffalo, Buffalo, New York 14260, Department of Chemistry, Middle Tennessee State University, Mufreesboro, Tennessee 37132, and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
| | - Marc Messerschmidt
- Department of Chemistry, University of New York at Buffalo, Buffalo, New York 14260, Department of Chemistry, Middle Tennessee State University, Mufreesboro, Tennessee 37132, and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
| | - Milan Gembicky
- Department of Chemistry, University of New York at Buffalo, Buffalo, New York 14260, Department of Chemistry, Middle Tennessee State University, Mufreesboro, Tennessee 37132, and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
| | - Mateusz Pitak
- Department of Chemistry, University of New York at Buffalo, Buffalo, New York 14260, Department of Chemistry, Middle Tennessee State University, Mufreesboro, Tennessee 37132, and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
| | - Anatoliy Volkov
- Department of Chemistry, University of New York at Buffalo, Buffalo, New York 14260, Department of Chemistry, Middle Tennessee State University, Mufreesboro, Tennessee 37132, and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
| | - Philip Coppens
- Department of Chemistry, University of New York at Buffalo, Buffalo, New York 14260, Department of Chemistry, Middle Tennessee State University, Mufreesboro, Tennessee 37132, and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
| | - Benjamin G. Harvey
- Department of Chemistry, University of New York at Buffalo, Buffalo, New York 14260, Department of Chemistry, Middle Tennessee State University, Mufreesboro, Tennessee 37132, and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
| | - Gregory C. Turpin
- Department of Chemistry, University of New York at Buffalo, Buffalo, New York 14260, Department of Chemistry, Middle Tennessee State University, Mufreesboro, Tennessee 37132, and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
| | - Atta M. Arif
- Department of Chemistry, University of New York at Buffalo, Buffalo, New York 14260, Department of Chemistry, Middle Tennessee State University, Mufreesboro, Tennessee 37132, and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
| | - Richard D. Ernst
- Department of Chemistry, University of New York at Buffalo, Buffalo, New York 14260, Department of Chemistry, Middle Tennessee State University, Mufreesboro, Tennessee 37132, and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112
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Wilson AM, Rheingold AL, Waldman TE, Klein M, West FG, Ernst RD. Fused ring systems derived from reactions of half-open titanocenes with diynes: Syntheses, characterization, cage rearrangements, and structural studies. J Organomet Chem 2009. [DOI: 10.1016/j.jorganchem.2008.09.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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26
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Boulho C, Keys T, Coppel Y, Vendier L, Etienne M, Locati A, Bessac F, Maseras F, Pantazis DA, McGrady JE. C−C Coupling Constants, JCC, Are Reliable Probes for α-C−C Agostic Structures. Organometallics 2009. [DOI: 10.1021/om800999a] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Cédric Boulho
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205, route de Narbonne, F-31077 Toulouse, France, and Université de Toulouse, UPS, INPT, LCC, F-31077 Toulouse, France, Institute of Chemical Research of Catalonia (ICIQ), Avgda. Països Catalans 16, 43007, Tarragona, Spain, Unitat de Química Física, Edifici Cn, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia, Spain, and WestCHEM, Department of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Tracy Keys
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205, route de Narbonne, F-31077 Toulouse, France, and Université de Toulouse, UPS, INPT, LCC, F-31077 Toulouse, France, Institute of Chemical Research of Catalonia (ICIQ), Avgda. Països Catalans 16, 43007, Tarragona, Spain, Unitat de Química Física, Edifici Cn, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia, Spain, and WestCHEM, Department of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Yannick Coppel
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205, route de Narbonne, F-31077 Toulouse, France, and Université de Toulouse, UPS, INPT, LCC, F-31077 Toulouse, France, Institute of Chemical Research of Catalonia (ICIQ), Avgda. Països Catalans 16, 43007, Tarragona, Spain, Unitat de Química Física, Edifici Cn, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia, Spain, and WestCHEM, Department of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Laure Vendier
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205, route de Narbonne, F-31077 Toulouse, France, and Université de Toulouse, UPS, INPT, LCC, F-31077 Toulouse, France, Institute of Chemical Research of Catalonia (ICIQ), Avgda. Països Catalans 16, 43007, Tarragona, Spain, Unitat de Química Física, Edifici Cn, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia, Spain, and WestCHEM, Department of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Michel Etienne
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205, route de Narbonne, F-31077 Toulouse, France, and Université de Toulouse, UPS, INPT, LCC, F-31077 Toulouse, France, Institute of Chemical Research of Catalonia (ICIQ), Avgda. Països Catalans 16, 43007, Tarragona, Spain, Unitat de Química Física, Edifici Cn, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia, Spain, and WestCHEM, Department of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Abel Locati
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205, route de Narbonne, F-31077 Toulouse, France, and Université de Toulouse, UPS, INPT, LCC, F-31077 Toulouse, France, Institute of Chemical Research of Catalonia (ICIQ), Avgda. Països Catalans 16, 43007, Tarragona, Spain, Unitat de Química Física, Edifici Cn, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia, Spain, and WestCHEM, Department of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Fabienne Bessac
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205, route de Narbonne, F-31077 Toulouse, France, and Université de Toulouse, UPS, INPT, LCC, F-31077 Toulouse, France, Institute of Chemical Research of Catalonia (ICIQ), Avgda. Països Catalans 16, 43007, Tarragona, Spain, Unitat de Química Física, Edifici Cn, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia, Spain, and WestCHEM, Department of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Feliu Maseras
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205, route de Narbonne, F-31077 Toulouse, France, and Université de Toulouse, UPS, INPT, LCC, F-31077 Toulouse, France, Institute of Chemical Research of Catalonia (ICIQ), Avgda. Països Catalans 16, 43007, Tarragona, Spain, Unitat de Química Física, Edifici Cn, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia, Spain, and WestCHEM, Department of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Dimitrios A. Pantazis
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205, route de Narbonne, F-31077 Toulouse, France, and Université de Toulouse, UPS, INPT, LCC, F-31077 Toulouse, France, Institute of Chemical Research of Catalonia (ICIQ), Avgda. Països Catalans 16, 43007, Tarragona, Spain, Unitat de Química Física, Edifici Cn, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia, Spain, and WestCHEM, Department of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - John E. McGrady
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205, route de Narbonne, F-31077 Toulouse, France, and Université de Toulouse, UPS, INPT, LCC, F-31077 Toulouse, France, Institute of Chemical Research of Catalonia (ICIQ), Avgda. Països Catalans 16, 43007, Tarragona, Spain, Unitat de Química Física, Edifici Cn, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia, Spain, and WestCHEM, Department of Chemistry, Joseph Black Building, University of Glasgow, Glasgow G12 8QQ, United Kingdom
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Rowley CN, van der Eide EF, Piers WE, Woo TK. DFT Study of the Isomerization and Spectroscopic/Structural Properties of Ruthenacyclobutane Intermediates Relevant to Olefin Metathesis. Organometallics 2008. [DOI: 10.1021/om8008519] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Christopher N. Rowley
- Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, 10 Marie-Curie, Ottawa, Ontario K1N 6N5, Canada, and Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
| | - Edwin F. van der Eide
- Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, 10 Marie-Curie, Ottawa, Ontario K1N 6N5, Canada, and Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
| | - Warren E. Piers
- Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, 10 Marie-Curie, Ottawa, Ontario K1N 6N5, Canada, and Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
| | - Tom K. Woo
- Centre for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, 10 Marie-Curie, Ottawa, Ontario K1N 6N5, Canada, and Department of Chemistry, University of Calgary, 2500 University Drive N.W., Calgary, Alberta T2N 1N4, Canada
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Harvey BG, Arif AM, Ernst RD. The reaction of the bis(6,6-dimethylcyclohexadienyl)zirconium fragment with PhC2SiMe3 – A 5+2+2 ring construction. J Mol Struct 2008. [DOI: 10.1016/j.molstruc.2008.04.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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29
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Harvey BG, Basta R, Arif AM, Ernst RD. Reactions of the 6,6-dimethylcyclohexadienyl anion with MCl4(PMe3)2 complexes (M=Hf, Nb) – Isolation of complex intramolecular coupling products. J Organomet Chem 2008. [DOI: 10.1016/j.jorganchem.2007.06.051] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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30
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van der Eide EF, Romero PE, Piers WE. Generation and Spectroscopic Characterization of Ruthenacyclobutane and Ruthenium Olefin Carbene Intermediates Relevant to Ring Closing Metathesis Catalysis. J Am Chem Soc 2008; 130:4485-91. [DOI: 10.1021/ja710364e] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Edwin F. van der Eide
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Canada T2N 1N4
| | - Patricio E. Romero
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Canada T2N 1N4
| | - Warren E. Piers
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Canada T2N 1N4
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31
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Harvey BG, Kulsomphob V, Arif AM, Ernst RD. Edge-bridged half-open zirconocenes: Synthesis, characterization, and reaction with diphenylacetylene. J Organomet Chem 2007. [DOI: 10.1016/j.jorganchem.2007.02.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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32
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Perutz RN, Sabo-Etienne S. The sigma-CAM Mechanism: sigma complexes as the basis of sigma-bond metathesis at late-transition-metal centers. Angew Chem Int Ed Engl 2007; 46:2578-92. [PMID: 17380532 DOI: 10.1002/anie.200603224] [Citation(s) in RCA: 482] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Complexes in which a sigma-H--E bond (E=H, B, Si, C) acts as a two-electron donor to the metal center are called sigma complexes. Clues that it is possible to interconvert sigma ligands without a change in oxidation state derive from C--H activation reactions effecting isotope exchange and from dynamic rearrangements of sigma complexes (see Frontispiece). Through these pathways, metathesis of M--E bonds can occur at late transition metals. We call this process sigma-complex-assisted metathesis, or sigma-CAM, which is distinct from the familiar sigma-bond metathesis (typical for d(0) metals and requiring no intermediate) and from oxidative-reductive elimination mechanisms (inherently requiring intermediates with changed oxidation states and sometimes involving sigma complexes). There are examples of sigma-CAM mechanisms in catalysis, especially for alkane borylation and isotope exchange of alkanes. It may also occur in silylation and alkene hydrogenation.
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Affiliation(s)
- Robin N Perutz
- Department of Chemistry, University of York, York, YO10 5DD, UK.
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Poater A, Solans-Monfort X, Clot E, Copéret C, Eisenstein O. Understanding d0-Olefin Metathesis Catalysts: Which Metal, Which Ligands? J Am Chem Soc 2007; 129:8207-16. [PMID: 17559212 DOI: 10.1021/ja070625y] [Citation(s) in RCA: 197] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Density functional theory (DFT, B3PW91) calculations have been carried out on the reactivity of ethene with model systems M(NR)(=CHCH3)(X)(Y) for M = Mo or W, R = methyl or phenyl, X = CH2CH3, OCH3, or OSiH3, and Y = CH2CH3, OCH3, or OSiH3, which are representative of experimental olefin metathesis catalysts, and the results are compared to those previously obtained for Re(CCH3)(=CHCH3)(X)(Y). The general pathway comprises four steps: olefin coordination, [2+2] cycloaddition, cycloreversion, and olefin de-coordination. Two key factors have been found to control the detailed shape of the energy profiles: the energy of distortion of the tetrahedral catalyst and the stability of the metallacycle intermediate, which is controlled by the M-C bond strength. The efficiency has been evaluated by calculating the turnover frequency (TOF) based on the steady-state approximation, and the most striking feature is that the unsymmetrical catalysts (X not equal to Y) are systematically more efficient for all systems (Mo, W, and Re). Overall, the Re complexes have been found to be less efficient than the Mo and W catalysts, except when Re is unsymmetrically substituted: it is then calculated to be as efficient as the best Mo and W catalysts.
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Affiliation(s)
- Albert Poater
- Institut Charles Gerhardt, Université Montpellier 2, CNRS, Case Courier 1501, Place E Bataillon, Chimie Théorique, Méthodologies, Modélisations, Montpellier, France
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Scheer M, Himmel D, Johnson B, Kuntz C, Schiffer M. Ringerweiterung einer Cp*-Einheit – Bildung eines 1,2-Diphosphacyclooctatetraen-Liganden. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200605173] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Scheer M, Himmel D, Johnson BP, Kuntz C, Schiffer M. Ring Expansion of a Cp* Moiety: Formation of a 1,2-Diphosphacyclooctatetraene Ligand. Angew Chem Int Ed Engl 2007; 46:3971-5. [PMID: 17427166 DOI: 10.1002/anie.200605173] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Manfred Scheer
- Institut für Anorganische Chemie der Universität Regensburg, 93040 Regensburg, Germany.
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Herndon JW. The chemistry of the carbon–transition metal double and triple bond: Annual survey covering the year 2005. Coord Chem Rev 2007. [DOI: 10.1016/j.ccr.2006.11.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Perutz R, Sabo-Etienne S. Der σ-CAM-Mechanismus: σ-Komplexe als Schlüssel der σ-Bindungsmetathese bei späten Übergangsmetallen. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200603224] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Romero PE, Piers WE. Mechanistic Studies on 14-Electron Ruthenacyclobutanes: Degenerate Exchange with Free Ethylene. J Am Chem Soc 2007; 129:1698-704. [PMID: 17243686 DOI: 10.1021/ja0675245] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The phosphonium alkylidene [(NHC)Cl2Ru=CH(PCy3)]+[B(C6F5)4]-, 1, (NHC = N-heterocyclic carbene, Cy = cyclohexyl, C6H11) reacts with 2.2 equiv of ethylene at -50 degrees C to form the 14-electron ruthenacyclobutane (NHC)Cl2Ru(CH2CH2CH2), 2. NMR spectroscopic data indicates that 2 has a C2v symmetric structure with a flat, kite shaped ruthenacyclobutane ring with significant Calpha-Cbeta agostic interactions with the Ru center. Intramolecular exchange of Calpha and Cbeta is fast (14(2) s-1 at 223 K) as measured by EXSY spectroscopy. Intermolecular exchange of Calpha and Cbeta with the methylene groups of free ethylene is much slower and first order in both [Ru] and [H2C=CH2] (4.8(3) x 10-4 M-1 s-1). Activation parameters for this process are DeltaH++ = 13.2(5) kcal mol-1 and DeltaS++ = -15(2) cal mol-1 K-1, also consistent with a rate limiting associative substitution as the key step in this exchange process. On the basis of this observation, mechanisms for the intermolecular exchange process are proposed and the implications for the mechanism of the propagation steps in catalytic olefin metathesis as mediated by Grubbs catalysts are discussed.
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Affiliation(s)
- Patricio E Romero
- University of Calgary, 2500 University Drive N.W., Calgary, Alberta, Canada T2N 1N4
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39
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Stahl L, Ernst RD. Pentadienyl Complexes of the Group 4 Transition Metals. ADVANCES IN ORGANOMETALLIC CHEMISTRY 2007. [DOI: 10.1016/s0065-3055(07)55003-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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Harvey BG, Arif AM, Ernst RD. Coupling reactions of alkynes with half-open titanocenes: Agostic (C–C)→Ti interactions in a tetra(alkyne) coupling product with the Ti(C5H5)(c-C8H11) fragment. J Organomet Chem 2006. [DOI: 10.1016/j.jorganchem.2006.08.086] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Sun Y, Chan HS, Zhao H, Lin Z, Xie Z. Ruthenium-Mediated Coupling/Cycloaddition of the Cyclopentadienyl Ligand in [{η5:σ-Me2C(C5H4)(C2B10H10)}Ru(NCCH3)2] with Alkynes. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200601650] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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43
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Sun Y, Chan HS, Zhao H, Lin Z, Xie Z. Ruthenium-Mediated Coupling/Cycloaddition of the Cyclopentadienyl Ligand in [{η5:σ-Me2C(C5H4)(C2B10H10)}Ru(NCCH3)2] with Alkynes. Angew Chem Int Ed Engl 2006; 45:5533-6. [PMID: 16847868 DOI: 10.1002/anie.200601650] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Yi Sun
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
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