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Andrew S Weller - One of the best experts on this subject based on the ideXlab platform.
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Fluoroarene complexes with small bite angle bisphosphines routes to amine borane and aminoborylene complexes
European Journal of Inorganic Chemistry, 2017Co-Authors: Annie L Colebatch, Stuart Macgregor, Alasdair I Mckay, Nicholas A Beattie, Andrew S WellerAbstract:Fluoroarene complexes of the small bite angle bisphosphine Cy2PCH2PCy2 (dcpm) have been prepared: [Rh(dcpm)(η6-1,2−F2C6H4)][Al{OC(CF3)3}4] and [Rh(dcpm)(η6-1,2,3− F3C6H3)][Al{OC(CF3)3}4]. These complexes act as precursors to a previously inaccessible σ−amine−borane complex [Rh(dcpm)(η2-H3B·NMe3)][Al{OC(CF3)3}4] of a small bite-angle phosphine. This complex is a poor catalyst for the dehydrocoupling of H3B·NMe2H. Instead, formation of the bridging borylene complex [{RhH(µ−dcpm)}2(µ−H)(µ−BNMe2)][Al{OC(CF3)3}4] occurs, which has been studied by NMR, mass spectrometry, crystallographic and DFT techniques. This represents a new route to bridging borylene complexes.
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Fluoroarene Complexes with Small Bite Angle Bisphosphines: Routes to Amine–Borane and Aminoborylene Complexes
European Journal of Inorganic Chemistry, 2017Co-Authors: Annie L Colebatch, Stuart Macgregor, Alasdair I Mckay, Nicholas A Beattie, Andrew S WellerAbstract:Fluoroarene complexes of the small bite angle bisphosphine Cy2PCH2PCy2 (dcpm) have been prepared: [Rh(dcpm)(η6-1,2−F2C6H4)][Al{OC(CF3)3}4] and [Rh(dcpm)(η6-1,2,3− F3C6H3)][Al{OC(CF3)3}4]. These complexes act as precursors to a previously inaccessible σ−amine−borane complex [Rh(dcpm)(η2-H3B·NMe3)][Al{OC(CF3)3}4] of a small bite-angle phosphine. This complex is a poor catalyst for the dehydrocoupling of H3B·NMe2H. Instead, formation of the bridging borylene complex [{RhH(µ−dcpm)}2(µ−H)(µ−BNMe2)][Al{OC(CF3)3}4] occurs, which has been studied by NMR, mass spectrometry, crystallographic and DFT techniques. This represents a new route to bridging borylene complexes.
Igor Larrosa - One of the best experts on this subject based on the ideXlab platform.
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meta-Selective olefination of Fluoroarenes with alkynes using CO2 as a traceless directing group
Chemical Science, 2020Co-Authors: Andrew R. A. Spencer, Marc Font, Rishi Korde, Igor LarrosaAbstract:Over the last few decades C–H olefination has received significant interest, due to the importance and usefulness of aryl olefins both as synthetic targets and intermediates. While a wide range of ortho-olefination protocols have been developed, only a small number of meta-olefinations are currently available. Importantly, the most common approach to meta-olefination, using a large meta-directing template, is not suitable for substrates such as fluorobenzenes, which cannot be derivatised. We report that the meta-selective olefination of Fluoroarenes can be achieved via the use of CO2 as a traceless directing group, which can be easily installed and removed in a one-pot process. Furthermore, this approach avoids the use of stoichiometric Ag(I)-salts, commonly used in C–H olefinations, and affords complete meta- over ortho/para-regioselectivity.
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ag pd cocatalyzed direct arylation of Fluoroarene derivatives with aryl bromides
ACS Catalysis, 2020Co-Authors: Adyasha Panigrahi, Daniel Whitaker, Inigo J Vitoricayrezabal, Igor LarrosaAbstract:Diverse C–H functionalizations catalyzed by Pd employ Ag(I) salts added as halide abstractors or oxidants. Recent reports have shown that Ag can also perform the crucial C–H activation step in seve...
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meta-C–H arylation of Fluoroarenes via traceless directing group relay strategy
Chemical Science, 2018Co-Authors: Marc Font, Andrew R. A. Spencer, Igor LarrosaAbstract:While several methods for the ortho selective arylation of Fluoroarenes, meta-functionalisation has never been achieved. We report a new methodology, based on the traceless directing group relay concept, leading to the first meta-selective (hetero)arylation of Fluoroarenes. In this strategy, CO2 is introduced as a transient directing group, to control a Pd-catalysed arylation meta to the fluoro functionality, prior to its release in a sequential, one-pot fashion. This method has shown compatibility with a number of functional groups and substitution patterns in both the Fluoroarene core and aryl iodide coupling partners, and proceeds with complete meta-selectivity and mono vs. bis-arylation selectivity.
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Ru-Catalyzed C–H Arylation of Fluoroarenes with Aryl Halides
Journal of the American Chemical Society, 2016Co-Authors: Marco Simonetti, Gregory J. P. Perry, Xacobe C. Cambeiro, Francisco Juliá-hernández, Jude N. Arokianathar, Igor LarrosaAbstract:Although the ruthenium-catalyzed C–H arylation of arenes bearing directing groups with haloarenes is well-known, this process has never been achieved in the absence of directing groups. We report the first example of such a process and show that unexpectedly the reaction only takes place in the presence of catalytic amounts of a benzoic acid. Furthermore, contrary to other transition metals, the arylation site selectivity is governed by both electronic and steric factors. Stoichiometric and NMR mechanistic studies support a catalytic cycle that involves a well-defined η6-arene-ligand-free Ru(II) catalyst. Indeed, upon initial pivalate-assisted C–H activation, the aryl-Ru(II) intermediate generated is able to react with an aryl bromide coupling partner only in the presence of a benzoate additive. In contrast, directing-group-containing substrates (such as 2-phenylpyridine) do not require a benzoate additive. Deuterium labeling and kinetic isotope effect experiments indicate that C–H activation is both reve...
Annie L Colebatch - One of the best experts on this subject based on the ideXlab platform.
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Fluoroarene complexes with small bite angle bisphosphines routes to amine borane and aminoborylene complexes
European Journal of Inorganic Chemistry, 2017Co-Authors: Annie L Colebatch, Stuart Macgregor, Alasdair I Mckay, Nicholas A Beattie, Andrew S WellerAbstract:Fluoroarene complexes of the small bite angle bisphosphine Cy2PCH2PCy2 (dcpm) have been prepared: [Rh(dcpm)(η6-1,2−F2C6H4)][Al{OC(CF3)3}4] and [Rh(dcpm)(η6-1,2,3− F3C6H3)][Al{OC(CF3)3}4]. These complexes act as precursors to a previously inaccessible σ−amine−borane complex [Rh(dcpm)(η2-H3B·NMe3)][Al{OC(CF3)3}4] of a small bite-angle phosphine. This complex is a poor catalyst for the dehydrocoupling of H3B·NMe2H. Instead, formation of the bridging borylene complex [{RhH(µ−dcpm)}2(µ−H)(µ−BNMe2)][Al{OC(CF3)3}4] occurs, which has been studied by NMR, mass spectrometry, crystallographic and DFT techniques. This represents a new route to bridging borylene complexes.
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Fluoroarene Complexes with Small Bite Angle Bisphosphines: Routes to Amine–Borane and Aminoborylene Complexes
European Journal of Inorganic Chemistry, 2017Co-Authors: Annie L Colebatch, Stuart Macgregor, Alasdair I Mckay, Nicholas A Beattie, Andrew S WellerAbstract:Fluoroarene complexes of the small bite angle bisphosphine Cy2PCH2PCy2 (dcpm) have been prepared: [Rh(dcpm)(η6-1,2−F2C6H4)][Al{OC(CF3)3}4] and [Rh(dcpm)(η6-1,2,3− F3C6H3)][Al{OC(CF3)3}4]. These complexes act as precursors to a previously inaccessible σ−amine−borane complex [Rh(dcpm)(η2-H3B·NMe3)][Al{OC(CF3)3}4] of a small bite-angle phosphine. This complex is a poor catalyst for the dehydrocoupling of H3B·NMe2H. Instead, formation of the bridging borylene complex [{RhH(µ−dcpm)}2(µ−H)(µ−BNMe2)][Al{OC(CF3)3}4] occurs, which has been studied by NMR, mass spectrometry, crystallographic and DFT techniques. This represents a new route to bridging borylene complexes.
René Wilhelm - One of the best experts on this subject based on the ideXlab platform.
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Palladium catalysed cross-coupling of (Fluoroarene)tricarbonylchromium(0) complexes
Journal of The Chemical Society-perkin Transactions 1, 2020Co-Authors: René Wilhelm, David A WiddowsonAbstract:(Fluoroarene)tricarbonylchromium(0) complexes were found to undergo Suzuki and Stille cross-coupling reactions to form functionalised biaryl and styrene complexes in up to 87 and 52% yields, respectively. The Suzuki reactions were optimal with dipalladium tris(dibenzylideneacetone)–trimethylphosphine–caesium carbonate in DME at reflux. The Stille reactions were optimal with dipalladium tris(dibenzylideneacetone)–trimethylphosphine–caesium fluoride in DME at reflux and neither was adversely affected by a methoxy group on the complexed ring. The Suzuki reaction tolerated a chloro group on the arylboronic acid ring but not a bromo group.
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Palladium catalysed Suzuki reactions of Fluoroarenes
Chemical Communications, 2003Co-Authors: David A Widdowson, René WilhelmAbstract:A novel palladium catalysed cleavage of C–F bonds in a series of Suzuki reactions of aryl fluorides is described together with a discussion of the mechanistic implications.
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palladium catalysed cross coupling of Fluoroarene tricarbonylchromium 0 complexes
Chemical Communications, 1999Co-Authors: David A Widdowson, René WilhelmAbstract:Fluoroarenetricarbonylchromium(0) complexes were found to undergo Suzuki reactions with arylboronic acids to form biaryltricarbonylchromium(0) complexes in the presence of trimethylphosphine/palladium dibenzylideneacetone and caesium carbonate or caesium fluoride.
Jikang Feng - One of the best experts on this subject based on the ideXlab platform.
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Theoretical studies on the electronic and optical properties of arene‐ versus Fluoroarene‐thiophene co‐oligomer
Journal of Physical Organic Chemistry, 2009Co-Authors: Jikang Feng, Wei Quan TianAbstract:A series of regiochemically varied and core size extension-modulated arene- and Fluoroarene-thiophene co-oligomers and the unsubstituted sexithiophene α6T were investigated theoretically to explore their electronic and optical properties. These phenylene-thiophene oligomers show great potential for application in organic light-emitting diodes (OLEDs), organic diode lasers, and organic thin-film transistors (OTFTs) because of their feasible tuning of optical and electronic properties by the various structural tunings. Density functional theory (DFT) and the ab initio HF were employed to investigate the geometric and electronic structures of the oligomers in the ground state, and the singles configuration interaction (CIS) methods were used to study the lowest singlet excited state. The lowest excitation energies (Egs), the radiative lifetime τ, and the maximal absorption/emission wavelength of the oligomers were studied within time-dependent DFT (TDDFT). All calculations were performed using the 6-31G(d) basis set. The results show that the HOMOs, LUMOs, energy gaps, ionization potentials (IPs), electron affinities (EAs), and reorganization energies are significantly affected by the various structural tunings in these co-oligomers, which is important for the improvement of the hole and electron injection into OLEDs. Interestingly, the LUMO energy of 1b, 2b, and 3b is lower than that of α6T and 1a, 2a, 3a by about 0.12 ∼ 0.47 eV, indicating that the fluorophenyl-substitution has significantly improved the electron injection properties of the oligomers. Copyright © 2008 John Wiley & Sons, Ltd.
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theoretical studies on the electronic and optical properties of arene versus Fluoroarene thiophene co oligomer
Journal of Physical Organic Chemistry, 2009Co-Authors: Jikang Feng, Wei Quan TianAbstract:A series of regiochemically varied and core size extension-modulated arene- and Fluoroarene-thiophene co-oligomers and the unsubstituted sexithiophene α6T were investigated theoretically to explore their electronic and optical properties. These phenylene-thiophene oligomers show great potential for application in organic light-emitting diodes (OLEDs), organic diode lasers, and organic thin-film transistors (OTFTs) because of their feasible tuning of optical and electronic properties by the various structural tunings. Density functional theory (DFT) and the ab initio HF were employed to investigate the geometric and electronic structures of the oligomers in the ground state, and the singles configuration interaction (CIS) methods were used to study the lowest singlet excited state. The lowest excitation energies (Egs), the radiative lifetime τ, and the maximal absorption/emission wavelength of the oligomers were studied within time-dependent DFT (TDDFT). All calculations were performed using the 6-31G(d) basis set. The results show that the HOMOs, LUMOs, energy gaps, ionization potentials (IPs), electron affinities (EAs), and reorganization energies are significantly affected by the various structural tunings in these co-oligomers, which is important for the improvement of the hole and electron injection into OLEDs. Interestingly, the LUMO energy of 1b, 2b, and 3b is lower than that of α6T and 1a, 2a, 3a by about 0.12 ∼ 0.47 eV, indicating that the fluorophenyl-substitution has significantly improved the electron injection properties of the oligomers. Copyright © 2008 John Wiley & Sons, Ltd.
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theoretical study on structural electronic and optical properties of ambipolar diphenylamino end capped oligofluorenylthiophenes and Fluoroarene thiophene as light emitting materials
Journal of Physical Chemistry A, 2008Co-Authors: Jikang FengAbstract:Ambipolar diphenylamino end-capped oligofluorenylthiophenes and Fluoroarene-thiophene show great potential for application in organic light-emitting diodes (OLEDs). Here, we provide an in-depth investigation on the optical and electronic properties of OF(2)TP-NPh (1a), OF(2)DTP-NPh (2a), OF(2)TTP-NPh (3a), OF(2)QTP-NPh (4a), and 2,5-bis-(2,3,5,6-tetrafluoro-4-trifluoromethyl-phenyl)-2,2′:5′,2′′:5′′,2′′′-quaterthiophene (5a). The geometric and electronic structures of the oligomers in the ground-state are studied with density functional theory (DFT) and ab initio Hartree-Fock, whereas the lowest singlet excited states are optimized by ab initio CIS. The energies of the lowest singlet excited states are calculated by employing time-dependent density functional theory (TDDFT). The results show that the highest occupied molecular orbitals, lowest unoccupied molecular orbitals, energy gaps, ionization potentials, and electron affinities for the oligomers are affected by the thiophene chain length and the diffe...