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Krishna Rao MV, Kareem S, Vali SR, Subba Reddy BV. Recent advances in metal directed C-H amidation/amination using sulfonyl azides and phosphoryl azides. Org Biomol Chem 2023; 21:8426-8462. [PMID: 37831479 DOI: 10.1039/d3ob01160g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2023]
Abstract
Transition metal-catalyzed C-N bond formation reactions have gained popularity as a method for selectively transforming common C-H bonds into N-functionalized molecules. This approach is particularly useful for synthesizing aminated molecules, which require aminating reagents and amidated building blocks. Over the past two decades, significant advancements have been achieved in transition-metal-catalyzed C-H functionalization, with organic azides emerging as promising amino sources and internal oxidants. This review focuses on recent developments in utilizing sulfonyl and phosphoryl azides as building blocks for directed intra- and intermolecular C-H functionalization reactions. Specifically, it discusses methods for synthesizing sulfonamidates and phosphoramidates using sulfonyl and phosphoryl azides, respectively. The article highlights the potential of C-H functionalization reactions with organic azides for efficiently and sustainably synthesizing N-functionalized molecules, providing valuable insights into the latest advancements in this field.
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Affiliation(s)
- M V Krishna Rao
- Department of Fluoro & Agrochemicals, CSIR-Indian Institute of Chemical Technology, Hyderabad-500 007, India.
| | - Shaik Kareem
- Department of Fluoro & Agrochemicals, CSIR-Indian Institute of Chemical Technology, Hyderabad-500 007, India.
| | - Shaik Ramjan Vali
- Department of Fluoro & Agrochemicals, CSIR-Indian Institute of Chemical Technology, Hyderabad-500 007, India.
| | - B V Subba Reddy
- Department of Fluoro & Agrochemicals, CSIR-Indian Institute of Chemical Technology, Hyderabad-500 007, India.
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2
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Balduf T, Blakemore JD, Caricato M. Computational Insights into the Influence of Ligands on Hydrogen Generation with [Cp*Rh] Hydrides. J Phys Chem A 2023. [PMID: 37436832 DOI: 10.1021/acs.jpca.3c02550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
This work reports a computational investigation of the effect of ancillary ligands on the activity of an Rh catalyst for hydrogen evolution based on the [Cp*Rh] motif (Cp* = η5-pentamethylcyclopentadienyl). Specifically, we investigate why a bipyridyl (bpy) ligand leads to H2 generation but diphenylphosphino-based (dpp) ligands do not. We compare the full ligands to simplified models and systematically vary structural features to ascertain their effect on the reaction energy of each catalytic step. The calculations based on density functional theory show that the main effect on reactivity is the choice of linker atom, followed by its coordination. In particular, P stabilizes the intermediate Rh-hydride species by donating electron density to the Rh, thus inhibiting the reaction toward H2 generation. Conversely, N, a more electron-withdrawing center, favors H2 generation at the price of destabilizing the hydride intermediate, which cannot be isolated experimentally and makes determining the mechanism of this reaction more difficult. We also find that the steric effects of bulky substituents on the main ligand scaffold can lead to large effects on the reactivity, which may be challenging to fine-tune. On the other hand, structural features like the bite angle of the bidentate ligand have a much smaller impact on reactivity. Therefore, we propose that the choice of linker atom is key for the catalytic activity of this species, which can be further fine-tuned by a proper choice of electron-directing groups on the ligand scaffold.
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Affiliation(s)
- Ty Balduf
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - James D Blakemore
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
| | - Marco Caricato
- Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States
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3
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Emerson-King J, Pan S, Gyton MR, Tonner-Zech R, Chaplin AB. Synthesis of a rhodium(III) dinitrogen complex using a calix[4]arene-based diphosphine ligand. Chem Commun (Camb) 2023; 59:2150-2152. [PMID: 36727440 PMCID: PMC9933454 DOI: 10.1039/d2cc06837k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The synthesis and characterisation of the rhodium(III) dinitrogen complex [Rh(2,2'-biphenyl)(CxP2)(N2)]+ are described, where CxP2 is a trans-spanning calix[4]arene-based diphosphine and the dinitrogen ligand is projected into the cavity of the macrocycle.
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Affiliation(s)
- Jack Emerson-King
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK.
| | - Sudip Pan
- Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität LeipzigLinnéstraße 2LeipzigD-04103Germany
| | - Matthew R. Gyton
- Department of Chemistry, University of WarwickGibbet Hill RoadCoventryCV4 7ALUK
| | - Ralf Tonner-Zech
- Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität LeipzigLinnéstraße 2LeipzigD-04103Germany
| | - Adrian B. Chaplin
- Department of Chemistry, University of WarwickGibbet Hill RoadCoventryCV4 7ALUK
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4
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Poole EW, Bustos I, Hood TM, Smart JE, Chaplin AB. Iridium complexes of an ortho-trifluoromethylphenyl substituted PONOP pincer ligand. Dalton Trans 2023; 52:1096-1104. [PMID: 36602231 PMCID: PMC9872493 DOI: 10.1039/d2dt03608h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The synthesis and iridium coordination chemistry of a new pyridine-based phosphinito pincer ligand 2,6-(ArF2PO)2C5H3N (PONOP-ArF; ArF = 2-(CF3)C6H4) are described, where the P-donors have ortho-trifluoromethylphenyl substituents. The iridium(III) 2,2'-biphenyl (biph) derivative [Ir(PONOP-ArF)(biph)Cl] was obtained by reaction with [Ir(biph)(COD)Cl]2 (COD = 1,5-cyclooctadiene) and subsequent halide ion abstraction enabled isolation of [Ir(PONOP-ArF)(biph)]+ which features an Ir ← F-C bonding interaction in the solid state. Hydrogenolysis of the biphenyl ligand and formation of [Ir(PONOP-ArF)(H)2]+ was achieved by prolonged reaction of [Ir(PONOP-ArF)(biph)]+ with dihydrogen. This transformation paved the way for isolation and crystallographic characterisation of low valent iridium derivatives through treatment of the dihydride with tert-butylethylene (TBE). The iridium(I) π-complex [Ir(PONOP-ArF)(TBE)]+ is thermally stable but substitution of TBE can be achieved by reaction with carbon monoxide. The solid-state structure of the mono-carbonyl product [Ir(PONOP-ArF)(CO)]+ is notable for an intermolecular anagostic interaction between the metal centre and a pentane molecule which co-crystallises within a cleft defined by two aryl phosphine substituents.
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Affiliation(s)
- Ethan W. Poole
- Department of Chemistry, University of WarwickGibbet Hill RoadCoventry CV4 7ALUK
| | - Itxaso Bustos
- Department of Chemistry, University of WarwickGibbet Hill RoadCoventry CV4 7ALUK,Facultad de Química de San Sebastián, Universidad del País Vasco (UPV/EHU)Apdo. 107220080 San SebastiánSpain
| | - Thomas M. Hood
- Department of Chemistry, University of WarwickGibbet Hill RoadCoventry CV4 7ALUK
| | - Jennifer E. Smart
- Department of Chemistry, University of WarwickGibbet Hill RoadCoventry CV4 7ALUK
| | - Adrian B. Chaplin
- Department of Chemistry, University of WarwickGibbet Hill RoadCoventry CV4 7ALUK
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5
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Najera DC, Peñas-Defrutos MN, García-Melchor M, Fout AR. γ-Agostic interactions in ( MesCCC)Fe-Mes(L) complexes. Chem Commun (Camb) 2022; 58:9626-9629. [PMID: 35959650 DOI: 10.1039/d2cc03260k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Agostic interactions were observed in the bound mesityl group in a series of iron compounds bearing a bis(NHC) pincer CCC ligand. The L-type ligand on [(CCC)FeIIMes(L)] complexes influences the strength of the agostic interaction and is manifested in the upfield shift of the 1H NMR resonance for the mesityl methyl resonances. The nature of the interaction was further investigated by density functional theory calculations, allowing rationalization of some unexpected trends and proving to be a powerful predictive tool.
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Affiliation(s)
- Daniel C Najera
- School of Chemical Sciences, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, Illinois 61801, USA.
| | - Marconi N Peñas-Defrutos
- School of Chemistry, CRANN and AMBER Research Centres, Trinity College Dublin, College Green, Dublin 2, Ireland. .,Universidad de Valladolid, Valladolid, Spain
| | - Max García-Melchor
- School of Chemistry, CRANN and AMBER Research Centres, Trinity College Dublin, College Green, Dublin 2, Ireland.
| | - Alison R Fout
- School of Chemical Sciences, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, Illinois 61801, USA.
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6
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The continuum of carbon-hydrogen (C-H) activation mechanisms and terminology. Commun Chem 2021; 4:173. [PMID: 36697593 PMCID: PMC9814233 DOI: 10.1038/s42004-021-00611-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 11/22/2021] [Indexed: 01/28/2023] Open
Abstract
As a rapidly growing field across all areas of chemistry, C-H activation/functionalisation is being used to access a wide range of important molecular targets. Of particular interest is the development of a sustainable methodology for alkane functionalisation as a means for reducing hydrocarbon emissions. This Perspective aims to give an outline to the community with respect to commonly used terminology in C-H activation, as well as the mechanisms that are currently understood to operate for (cyclo)alkane activation/functionalisation.
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González‐Montiel S, Ignacio Sandoval‐Chávez C, Castillo‐Moreno MÁ, Mendoza‐Espinosa D, Manuel Vásquez‐Pérez J, Cruz‐Borbolla J, Salazar‐Pereda V. Coordination from Heteroscorpionate Ligand Towards Pd(II) via Pd⋅⋅⋅Hδ−C(sp3) Interaction: Structural and Catalytic Studies. Eur J Inorg Chem 2021. [DOI: 10.1002/ejic.202100351] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Simplicio González‐Montiel
- Área Académica de Química, Centro de Investigaciones Químicas Universidad Autónoma del Estado de Hidalgo km. 14.5 Carretera Pachuca-Tulancingo, Ciudad del Conocimiento C.P. 42184, Mineral de la Reforma Hidalgo México
| | - César Ignacio Sandoval‐Chávez
- CONACYT Research-Fellow, Área Académica de Química, Centro de Investigaciones Químicas Universidad Autónoma del Estado de Hidalgo km. 14.5 Carretera Pachuca-Tulancingo, Ciudad del Conocimiento C. P. 42184, Mineral de la Reforma Hidalgo México
| | - Miguel Ángel Castillo‐Moreno
- Área Académica de Química, Centro de Investigaciones Químicas Universidad Autónoma del Estado de Hidalgo km. 14.5 Carretera Pachuca-Tulancingo, Ciudad del Conocimiento C.P. 42184, Mineral de la Reforma Hidalgo México
| | - Daniel Mendoza‐Espinosa
- Área Académica de Química, Centro de Investigaciones Químicas Universidad Autónoma del Estado de Hidalgo km. 14.5 Carretera Pachuca-Tulancingo, Ciudad del Conocimiento C.P. 42184, Mineral de la Reforma Hidalgo México
| | - José Manuel Vásquez‐Pérez
- CONACYT Research-Fellow, Área Académica de Química, Centro de Investigaciones Químicas Universidad Autónoma del Estado de Hidalgo km. 14.5 Carretera Pachuca-Tulancingo, Ciudad del Conocimiento C. P. 42184, Mineral de la Reforma Hidalgo México
| | - Julián Cruz‐Borbolla
- Área Académica de Química, Centro de Investigaciones Químicas Universidad Autónoma del Estado de Hidalgo km. 14.5 Carretera Pachuca-Tulancingo, Ciudad del Conocimiento C.P. 42184, Mineral de la Reforma Hidalgo México
| | - Verónica Salazar‐Pereda
- Área Académica de Química, Centro de Investigaciones Químicas Universidad Autónoma del Estado de Hidalgo km. 14.5 Carretera Pachuca-Tulancingo, Ciudad del Conocimiento C.P. 42184, Mineral de la Reforma Hidalgo México
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8
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Race JJ, Burnage AL, Boyd TM, Heyam A, Martínez-Martínez AJ, Macgregor SA, Weller AS. Ortho-aryl substituted DPEphos ligands: rhodium complexes featuring C-H anagostic interactions and B-H agostic bonds. Chem Sci 2021; 12:8832-8843. [PMID: 34257884 PMCID: PMC8246285 DOI: 10.1039/d1sc01430g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 05/24/2021] [Indexed: 11/29/2022] Open
Abstract
The synthesis of new Schrock–Osborn Rh(i) pre-catalysts with ortho-substituted DPEphos ligands, [Rh(DPEphos-R)(NBD)][BArF4] [R = Me, OMe, iPr; ArF = 3,5-(CF3)2C6H3], is described. Along with the previously reported R = H variant, variable temperature 1H NMR spectroscopic and single-crystal X-ray diffraction studies show that these all have axial (C–H)⋯Rh anagostic interactions relative to the d8 pseudo square planar metal centres, that also result in corresponding downfield chemical shifts. Analysis by NBO, QTAIM and NCI methods shows these to be only very weak C–H⋯Rh bonding interactions, the magnitudes of which do not correlate with the observed chemical shifts. Instead, as informed by Scherer's approach, it is the topological positioning of the C–H bond with regard to the metal centre that is important. For [Rh(DPEphos–iPr)(NBD)][BArF4] addition of H2 results in a Rh(iii) iPr–C–H activated product, [Rh(κ3,σ-P,O,P-DPEphos-iPr′)(H)][BArF4]. This undergoes H/D exchange with D2 at the iPr groups, reacts with CO or NBD to return Rh(i) products, and reaction with H3B·NMe3/tert-butylethene results in a dehydrogenative borylation to form a complex that shows both a non-classical B–H⋯Rh 3c-2e agostic bond and a C–H⋯Rh anagostic interaction at the same metal centre. Rh(i) complexes of ortho-substituted DPEphos-R (R = H, Me, OMe, iPr) ligands show anagostic interactions; for R =iPr C–H activation/dehydrogenative borylation forms a product exhibiting both B–H/Rh 3c-2e agostic and C–H/Rh anagostic motifs.![]()
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Affiliation(s)
- James J Race
- Department of Chemistry, University of York Heslington York YO10 5DD UK .,Chemistry Research Laboratories, University of Oxford Oxford OX1 3TA UK
| | - Arron L Burnage
- Institute of Chemical Sciences, Heriot Watt University Edinburgh EH14 4AS UK
| | - Timothy M Boyd
- Department of Chemistry, University of York Heslington York YO10 5DD UK .,Chemistry Research Laboratories, University of Oxford Oxford OX1 3TA UK
| | - Alex Heyam
- Chemistry Research Laboratories, University of Oxford Oxford OX1 3TA UK
| | | | - Stuart A Macgregor
- Institute of Chemical Sciences, Heriot Watt University Edinburgh EH14 4AS UK
| | - Andrew S Weller
- Department of Chemistry, University of York Heslington York YO10 5DD UK
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9
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Storey CM, Gyton MR, Andrew RE, Chaplin AB. Terminal Alkyne Coupling Reactions Through a Ring: Effect of Ring Size on Rate and Regioselectivity. Chemistry 2020; 26:14715-14723. [PMID: 32677713 PMCID: PMC7756505 DOI: 10.1002/chem.202002962] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 07/15/2020] [Indexed: 01/11/2023]
Abstract
Terminal alkyne coupling reactions promoted by rhodium(I) complexes of macrocyclic NHC-based pincer ligands-which feature dodecamethylene, tetradecamethylene or hexadecamethylene wingtip linkers viz. [Rh(CNC-n)(C2 H4 )][BArF 4 ] (n=12, 14, 16; ArF =3,5-(CF3 )2 C6 H3 )-have been investigated, using the bulky alkynes HC≡CtBu and HC≡CAr' (Ar'=3,5-tBu2 C6 H3 ) as substrates. These stoichiometric reactions proceed with formation of rhodium(III) alkynyl alkenyl derivatives and produce rhodium(I) complexes of conjugated 1,3-enynes by C-C bond reductive elimination through the annulus of the ancillary ligand. The intermediates are formed with orthogonal regioselectivity, with E-alkenyl complexes derived from HC≡CtBu and gem-alkenyl complexes derived from HC≡CAr', and the reductive elimination step is appreciably affected by the ring size of the macrocycle. For the homocoupling of HC≡CtBu, E-tBuC≡CCH=CHtBu is produced via direct reductive elimination from the corresponding rhodium(III) alkynyl E-alkenyl derivatives with increasing efficacy as the ring is expanded. In contrast, direct reductive elimination of Ar'C≡CC(=CH2 )Ar' is encumbered relative to head-to-head coupling of HC≡CAr' and it is only with the largest macrocyclic ligand studied that the two processes are competitive. These results showcase how macrocyclic ligands can be used to interrogate the mechanism and tune the outcome of terminal alkyne coupling reactions, and are discussed with reference to catalytic reactions mediated by the acyclic homologue [Rh(CNC-Me)(C2 H4 )][BArF 4 ] and solvent effects.
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Affiliation(s)
- Caroline M. Storey
- Department of ChemistryUniversity of WarwickGibbet Hill RoadCoventryCV4 7ALUK
| | - Matthew R. Gyton
- Department of ChemistryUniversity of WarwickGibbet Hill RoadCoventryCV4 7ALUK
| | - Rhiann E. Andrew
- Department of ChemistryUniversity of WarwickGibbet Hill RoadCoventryCV4 7ALUK
| | - Adrian B. Chaplin
- Department of ChemistryUniversity of WarwickGibbet Hill RoadCoventryCV4 7ALUK
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10
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Gyton MR, Kynman AE, Leforestier B, Gallo A, Lewandowski JR, Chaplin AB. Isolation and structural characterisation of rhodium(iii) η 2-fluoroarene complexes: experimental verification of predicted regioselectivity. Dalton Trans 2020; 49:5791-5793. [PMID: 32314773 DOI: 10.1039/d0dt01137a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The isolation and solid-state characterisation of complexes featuring partially coordinated benzene, fluorobenzene and all three isomers of difluorobenzene are described. Supported by a DFT analysis, this well-defined homologous series demonstrates the preference for η2-coordination of fluoroarenes via the HC[double bond, length as m-dash]CH sites adjacent to a fluorine substituent.
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Affiliation(s)
- Matthew R Gyton
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK.
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11
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Boyd TM, Tegner BE, Tizzard GJ, Martínez‐Martínez AJ, Neale SE, Hayward MA, Coles SJ, Macgregor SA, Weller AS. A Structurally Characterized Cobalt(I) σ-Alkane Complex. Angew Chem Int Ed Engl 2020; 59:6177-6181. [PMID: 31943626 PMCID: PMC7187152 DOI: 10.1002/anie.201914940] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Indexed: 11/11/2022]
Abstract
A cobalt σ-alkane complex, [Co(Cy2 P(CH2 )4 PCy2 )(norbornane)][BArF 4 ], was synthesized by a single-crystal to single-crystal solid/gas hydrogenation from a norbornadiene precursor, and its structure was determined by X-ray crystallography. Magnetic data show this complex to be a triplet. Periodic DFT and electronic structure analyses revealed weak C-H→Co σ-interactions, augmented by dispersive stabilization between the alkane ligand and the anion microenvironment. The calculations are most consistent with a η1 :η1 -alkane binding mode.
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Affiliation(s)
- Timothy M. Boyd
- Chemistry Research LaboratoriesDepartment of ChemistryUniversity of OxfordOxfordOX1 3TAUK
- Department of ChemistryUniversity of YorkYorkYO10 5DDUK
| | - Bengt E. Tegner
- Institute of Chemical SciencesHeriot-Watt UniversityEdinburghEH14 4ASUK
| | - Graham J. Tizzard
- UK National Crystallography ServiceChemistryFaculty of Engineering and Physical SciencesUniversity of SouthamptonSouthamptonSO17 1BJUK
| | | | - Samuel E. Neale
- Institute of Chemical SciencesHeriot-Watt UniversityEdinburghEH14 4ASUK
| | - Michael A. Hayward
- Chemistry Research LaboratoriesDepartment of ChemistryUniversity of OxfordOxfordOX1 3TAUK
| | - Simon J. Coles
- UK National Crystallography ServiceChemistryFaculty of Engineering and Physical SciencesUniversity of SouthamptonSouthamptonSO17 1BJUK
| | | | - Andrew S. Weller
- Chemistry Research LaboratoriesDepartment of ChemistryUniversity of OxfordOxfordOX1 3TAUK
- Department of ChemistryUniversity of YorkYorkYO10 5DDUK
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12
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Boyd TM, Tegner BE, Tizzard GJ, Martínez‐Martínez AJ, Neale SE, Hayward MA, Coles SJ, Macgregor SA, Weller AS. A Structurally Characterized Cobalt(I) σ‐Alkane Complex. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201914940] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Timothy M. Boyd
- Chemistry Research LaboratoriesDepartment of ChemistryUniversity of Oxford Oxford OX1 3TA UK
- Department of ChemistryUniversity of York York YO10 5DD UK
| | - Bengt E. Tegner
- Institute of Chemical SciencesHeriot-Watt University Edinburgh EH14 4AS UK
| | - Graham J. Tizzard
- UK National Crystallography ServiceChemistryFaculty of Engineering and Physical SciencesUniversity of Southampton Southampton SO17 1BJ UK
| | | | - Samuel E. Neale
- Institute of Chemical SciencesHeriot-Watt University Edinburgh EH14 4AS UK
| | - Michael A. Hayward
- Chemistry Research LaboratoriesDepartment of ChemistryUniversity of Oxford Oxford OX1 3TA UK
| | - Simon J. Coles
- UK National Crystallography ServiceChemistryFaculty of Engineering and Physical SciencesUniversity of Southampton Southampton SO17 1BJ UK
| | | | - Andrew S. Weller
- Chemistry Research LaboratoriesDepartment of ChemistryUniversity of Oxford Oxford OX1 3TA UK
- Department of ChemistryUniversity of York York YO10 5DD UK
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13
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Hood TM, Gyton MR, Chaplin AB. Synthesis and rhodium complexes of macrocyclic PNP and PONOP pincer ligands. Dalton Trans 2020; 49:2077-2086. [PMID: 31912067 DOI: 10.1039/c9dt04474d] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthesis of macrocyclic variants of commonly employed phosphine-based pincer ligands derived from lutidine (PNP-14) and 2,6-dihydroxypyridine (PONOP-14) is described, where the P-donors are trans-substituted with a tetradecamethylene linker. This was accomplished using an eight-step procedure involving borane protection, ring-closing olefin metathesis, chromatographic separation from the cis-substituted diastereomers, and borane deprotection. The rhodium coordination chemistry of these ligands has been explored, aided by the facile synthesis of 2,2'-biphenyl (biph) adducts [Rh(PNP-14)(biph)][BArF4] and [Rh(PONOP-14)(biph)][BArF4] (ArF = 3,5-(CF3)2C6H3). Subsequent hydrogenolysis enabled generation of dihydrogen, ethylene and carbonyl derivatives; notably the ν(CO) bands of the carbonyl complexes provide a means to compare the donor properties of the new pincer ligands with established acyclic congeners.
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Affiliation(s)
- Thomas M Hood
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK.
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14
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Hood TM, Leforestier B, Gyton MR, Chaplin AB. Synthesis and Structural Dynamics of Five-Coordinate Rh(III) and Ir(III) PNP and PONOP Pincer Complexes. Inorg Chem 2019; 58:7593-7601. [PMID: 31117634 PMCID: PMC6549213 DOI: 10.1021/acs.inorgchem.9b00957] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The synthesis and characterization of a homologous series of five-coordinate rhodium(III) and iridium(III) complexes of PNP (2,6-( tBu2PCH2)2C5H3N) and PONOP (2,6-( tBu2PO)2C5H3N) pincer ligands are described: [M(PNP)(biph)][BArF4] (M = Rh, 1a; Ir, 1b; biph = 2,2'-biphenyl; ArF = 3,5-(CF3)2C6H3) and [M(PONOP)(biph)][BArF4] (M = Rh, 2a; Ir, 2b). These complexes are structurally dynamic in solution, exhibiting pseudorotation of the biph ligand on the 1H NMR time scale (Δ G⧧ ca. 60 kJ mol-1) and, in the case of the flexible PNP complexes, undergoing interconversion between helical and puckered pincer ligand conformations (Δ G⧧ ca. 10 kJ mol-1). Remarkably, the latter is sufficiently facile that it persists in the solid state, leading to temperature-dependent disorder in the associated X-ray crystal structures. Reaction of 1 and 2 with CO occurs for the iridium congeners 1b and 2b, leading to the formation of sterically congested carbonyl derivatives.
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Affiliation(s)
- Thomas M Hood
- Department of Chemistry , University of Warwick , Gibbet Hill Road , Coventry CV4 7AL , U.K
| | - Baptiste Leforestier
- Department of Chemistry , University of Warwick , Gibbet Hill Road , Coventry CV4 7AL , U.K
| | - Matthew R Gyton
- Department of Chemistry , University of Warwick , Gibbet Hill Road , Coventry CV4 7AL , U.K
| | - Adrian B Chaplin
- Department of Chemistry , University of Warwick , Gibbet Hill Road , Coventry CV4 7AL , U.K
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15
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Emerson‐King J, Prokes I, Chaplin AB. Rhodium(III) Complexes Featuring Coordinated CF 3 Appendages. Chemistry 2019; 25:6317-6319. [PMID: 30875135 PMCID: PMC6519252 DOI: 10.1002/chem.201901184] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Indexed: 11/07/2022]
Abstract
The synthesis and characterisation of a homologous series of rhodium 2,2'-biphenyl complexes featuring intramolecular dative bonding of the nominally inert and weakly coordinating trifluoromethyl group are described. Presence of these interactions is evidenced in the solid state using X-ray diffraction, with Rh-F contacts of 2.36-2.45 Å, and in solution using NMR spectroscopy, through hindered C-CF3 bond rotation and the presence of time-averaged 1 JRhF and 2 JPF coupling.
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Affiliation(s)
- Jack Emerson‐King
- Department of ChemistryUniversity of WarwickGibbet Hill RoadCoventryCV4 7ALUK
| | - Ivan Prokes
- Department of ChemistryUniversity of WarwickGibbet Hill RoadCoventryCV4 7ALUK
| | - Adrian B. Chaplin
- Department of ChemistryUniversity of WarwickGibbet Hill RoadCoventryCV4 7ALUK
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16
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Gyton MR, Leforestier B, Chaplin AB. Rhodium(III) and Iridium(III) Complexes of a NHC-Based Macrocycle: Persistent Weak Agostic Interactions and Reactions with Dihydrogen. Organometallics 2018; 37:3963-3971. [PMID: 30449914 PMCID: PMC6234485 DOI: 10.1021/acs.organomet.8b00595] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Indexed: 11/29/2022]
Abstract
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The
synthesis and characterization of five-coordinate rhodium(III)
and iridium(III) 2,2′-biphenyl complexes [M(CNC-12)(biph)][BArF4] (M = Rh (1a), Ir (1b)), featuring the macrocyclic lutidine- and NHC-based pincer ligand
CNC-12 are reported. In the solid state these complexes are notable
for the adoption of weak ε-agostic interactions that are characterized
by M···H–C contacts of ca. 3.0 Å by X-ray crystallography and ν(CH)
bands of reduced wavenumber by ATR IR spectroscopy. Remarkably, these
interactions persist on dissolution and were observed at room temperature
using NMR spectroscopy (CD2Cl2) and solution-phase
IR spectroscopy (CCl4). The associated metrics point toward
a stronger M···H–C interaction in the iridium
congener, and this conclusion is borne out on interrogation of 1 in silico using DFT-based NBO and QTAIM analyses. Reaction
of 1 with dihydrogen resulted in hydrogenolysis of the
biaryl and formation of fluxional hydride complexes, whose ground
state formulations as [Rh(CNC-12)H2][BArF4] (2a″) and [Ir(CNC-12)H2(H2)][BArF4] (2b‴)
are proposed on the basis of inversion recovery and variable-temperature
NMR experiments, alongside a computational analysis. Reactions of 1 and 2 with carbon monoxide help support their
respective structural properties.
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Affiliation(s)
- Matthew R Gyton
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, U.K
| | - Baptiste Leforestier
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, U.K
| | - Adrian B Chaplin
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, U.K
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17
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Martínez-Martínez AJ, Tegner BE, McKay AI, Bukvic AJ, Rees NH, Tizzard GJ, Coles SJ, Warren MR, Macgregor SA, Weller AS. Modulation of σ-Alkane Interactions in [Rh(L 2)(alkane)] + Solid-State Molecular Organometallic (SMOM) Systems by Variation of the Chelating Phosphine and Alkane: Access to η 2,η 2-σ-Alkane Rh(I), η 1-σ-Alkane Rh(III) Complexes, and Alkane Encapsulation. J Am Chem Soc 2018; 140:14958-14970. [PMID: 30351014 DOI: 10.1021/jacs.8b09364] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Solid/gas single-crystal to single-crystal (SC-SC) hydrogenation of appropriate diene precursors forms the corresponding σ-alkane complexes [Rh(Cy2P(CH2) nPCy2)(L)][BArF4] ( n = 3, 4) and [ RhH(Cy2P(CH2)2( CH)(CH2)2PCy2)(L)][BArF4] ( n = 5, L = norbornane, NBA; cyclooctane, COA). Their structures, as determined by single-crystal X-ray diffraction, have cations exhibiting Rh···H-C σ-interactions which are modulated by both the chelating ligand and the identity of the alkane, while all sit in an octahedral anion microenvironment. These range from chelating η2,η2 Rh···H-C (e.g., [Rh(Cy2P(CH2) nPCy2)(η2η2-NBA)][BArF4], n = 3 and 4), through to more weakly bound η1 Rh···H-C in which C-H activation of the chelate backbone has also occurred (e.g., [ RhH(Cy2P(CH2)2( CH)(CH2)2PCy2)(η1-COA)][BArF4]) and ultimately to systems where the alkane is not ligated with the metal center, but sits encapsulated in the supporting anion microenvironment, [Rh(Cy2P(CH2)3PCy2)][COA⊂BArF4], in which the metal center instead forms two intramolecular agostic η1 Rh···H-C interactions with the phosphine cyclohexyl groups. CH2Cl2 adducts formed by displacement of the η1-alkanes in solution ( n = 5; L = NBA, COA), [ RhH(Cy2P(CH2)2( CH)(CH2)2PCy2)(κ1-ClCH2Cl)][BArF4], are characterized crystallographically. Analyses via periodic DFT, QTAIM, NBO, and NCI calculations, alongside variable temperature solid-state NMR spectroscopy, provide snapshots marking the onset of Rh···alkane interactions along a C-H activation trajectory. These are negligible in [Rh(Cy2P(CH2)3PCy2)][COA⊂BArF4]; in [ RhH(Cy2P(CH2)2( CH)(CH2)2PCy2)(η1-COA)][BArF4], σC-H → Rh σ-donation is supported by Rh → σ*C-H "pregostic" donation, and in [Rh(Cy2P(CH2) nPCy2)(η2η2-NBA)][BArF4] ( n = 2-4), σ-donation dominates, supported by classical Rh(dπ) → σ*C-H π-back-donation. Dispersive interactions with the [BArF4]- anions and Cy substituents further stabilize the alkanes within the binding pocket.
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Affiliation(s)
| | - Bengt E Tegner
- Institute of Chemical Sciences , Heriot-Watt University , Edinburgh EH14 4AS , United Kingdom
| | - Alasdair I McKay
- Chemistry Research Laboratories , University of Oxford , Oxford OX1 3TA , United Kingdom
| | - Alexander J Bukvic
- Chemistry Research Laboratories , University of Oxford , Oxford OX1 3TA , United Kingdom
| | - Nicholas H Rees
- Chemistry Research Laboratories , University of Oxford , Oxford OX1 3TA , United Kingdom
| | - Graham J Tizzard
- UK National Crystallography Service, Chemistry, Faculty of Natural and Environmental Sciences , University of Southampton , Southampton SO17 1BJ , United Kingdom
| | - Simon J Coles
- UK National Crystallography Service, Chemistry, Faculty of Natural and Environmental Sciences , University of Southampton , Southampton SO17 1BJ , United Kingdom
| | - Mark R Warren
- Harwell Science and Innovation Campus, Diamond Light Source Ltd. , Didcot OX11 0DE , United Kingdom
| | - Stuart A Macgregor
- Institute of Chemical Sciences , Heriot-Watt University , Edinburgh EH14 4AS , United Kingdom
| | - Andrew S Weller
- Chemistry Research Laboratories , University of Oxford , Oxford OX1 3TA , United Kingdom
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