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Srivastava N, Singh AK. Protic- or anionic-NHCs with a classical-NHC in a single [Ru(CNC)(PPh 3) 2Cl]Cl pincer complex: direct comparison of structure & electronic properties and heterolytic H 2 splitting. Dalton Trans 2024; 53:6870-6874. [PMID: 38597195 DOI: 10.1039/d4dt00623b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
Herein, we report the first set of pincer complexes 1 and 2 with the general formula [Ru(CNC)(PPh3)2Cl]Cl having a protic- and classical-NHC in the same molecule and nearly identical environments. Deprotonation of the protic-NHC complex 2 with one equivalent of base leads to the formation of anionic-NHC complex 2'. These complexes allow a direct comparison of protic- and anionic-NHCs with the classical-NHC ligand. A comparison of the molecular structure indicated that the metal carbene bond length trend is anionic-NHC > protic-NHC > classical-NHC. The electrochemical investigation revealed the electron donation tendency is classical-NHC > protic-NHC and anionic-NHC > protic-NHC. Cooperation between the metal and the ligand is indicated by the reaction of 2' with H2 gas at 1 atm pressure and 110 °C to give the Ru-hydride complex 3.
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Affiliation(s)
- Navdeep Srivastava
- Department of Chemistry, Indian Institute of Technology-Indore, Simrol, Khandwa Road, 433552, India.
| | - Amrendra K Singh
- Department of Chemistry, Indian Institute of Technology-Indore, Simrol, Khandwa Road, 433552, India.
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2
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Nath S, Yadav E, Raghuvanshi A, Singh AK. Ru(II) Complexes with Protic- and Anionic-Naked-NHC Ligands for Cooperative Activation of Small Molecules. Chemistry 2023; 29:e202301971. [PMID: 37377294 DOI: 10.1002/chem.202301971] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 06/27/2023] [Accepted: 06/28/2023] [Indexed: 06/29/2023]
Abstract
A set of ruthenium(II)-protic-N-heterocyclic carbene complexes, [Ru(NNCH )(PPh3 )2 (X)]Cl (1, X=Cl and 2, X=H) and their deprotonated forms [Ru(NNC)(PPh3 )2 (X)] (1', X=Cl and 2', X=H), in which NNC is a new unsymmetrical pincer ligand, are reported. The four complexes are interconvertible by simple acid-base chemistry. The combined theoretical and spectroscopic investigations indicate charge segregation in anionic-NHC complexes (1' and 2') and can be described from a Lewis pair perspective. The chemical reactivity of deprotonated complex 1' shows cooperative small molecule activation. Complex 1' activates H-H bond of hydrogen, C(sp3 )-I bond of iodomethane, and C(sp)-H bond of phenylacetylene. The activation of CO2 using anionic NHC complex 1' at moderate temperature and ambient pressure and subsequent conversion to formate is also described. All the new compounds have been characterized using ESI-MS, 1 H, 13 C, and 31 P NMR spectroscopy. Molecular structures of 1, 2, and 2' have also been determined with single-crystal X-ray diffraction. The cooperative small molecule activation perspective broadens the scope of potential applications of anionic-NHC complexes in small molecule activation, including the conversion of carbon dioxide to formate, a much sought after reaction in the renewable energy and sustainable development domains.
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Affiliation(s)
- Shambhu Nath
- Department of Chemistry, Indian Institute of Technology Indore, Simrol, Indore, 453552, India
| | - Ekta Yadav
- Department of Chemistry, Indian Institute of Technology Indore, Simrol, Indore, 453552, India
| | - Abhinav Raghuvanshi
- Department of Chemistry, Indian Institute of Technology Indore, Simrol, Indore, 453552, India
| | - Amrendra K Singh
- Department of Chemistry, Indian Institute of Technology Indore, Simrol, Indore, 453552, India
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3
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Vanston CR, Nicholls TP, Bissember AC, Gardiner MG, Ho CC. Cationic Charge-Appended Abnormal Carbenes: Synthesis and Study of Electronically Modified Abnormal N-Heterocyclic Carbenes. Inorg Chem 2021; 61:622-632. [PMID: 34941242 DOI: 10.1021/acs.inorgchem.1c03336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A range of palladium complexes featuring electronically modified, imidazole-based abnormal N-heterocyclic carbene (aNHC) ligands have been prepared in the hopes of accessing a new class of cationic aNHC ligands electronically distinct from normal NHCs and aNHCs. These palladium complexes represent the first examples of transition metal-ligated aNHC complexes featuring a cationic moiety adjacent to the abnormal carbene center. It was anticipated that these design principles could facilitate electron transfer between the imidazolinylidene and the cationic heterocycle, thus reducing the electron density at the abnormal carbene center. However, this case study suggests that greater conformational restrictions that allow for heterocycle coplanarity are necessary to achieve significant electron transfer and enable access to a new class of cationic charge-appended aNHCs with unique electronic properties.
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Affiliation(s)
- Catriona R Vanston
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Thomas P Nicholls
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Alex C Bissember
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Michael G Gardiner
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Curtis C Ho
- School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania 7001, Australia
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Martinez EE, Jensen CA, Larson AJS, Kenney KC, Clark KJ, Nazari SH, Valdivia‐Berroeta GA, Smith SJ, Ess DH, Michaelis DJ. Monosubstituted, Anionic Imidazolyl Ligands from N−H NHC Precursors and Their Activity in Pd‐Catalyzed Cross‐Coupling Reactions. Adv Synth Catal 2020. [DOI: 10.1002/adsc.202000483] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Erin E. Martinez
- Department of Chemistry and BiochemistryBrigham Young University Provo, Utah 84602 United States
| | - Christopher A. Jensen
- Department of Chemistry and BiochemistryBrigham Young University Provo, Utah 84602 United States
| | - Alexandra J. S. Larson
- Department of Chemistry and BiochemistryBrigham Young University Provo, Utah 84602 United States
| | - Karissa C. Kenney
- Department of Chemistry and BiochemistryBrigham Young University Provo, Utah 84602 United States
| | - Kyle J. Clark
- Department of Chemistry and BiochemistryBrigham Young University Provo, Utah 84602 United States
| | - S. Hadi Nazari
- Department of Chemistry and BiochemistryBrigham Young University Provo, Utah 84602 United States
| | | | - Stacey J. Smith
- Department of Chemistry and BiochemistryBrigham Young University Provo, Utah 84602 United States
| | - Daniel H. Ess
- Department of Chemistry and BiochemistryBrigham Young University Provo, Utah 84602 United States
| | - David J. Michaelis
- Department of Chemistry and BiochemistryBrigham Young University Provo, Utah 84602 United States
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5
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Evans KJ, Mansell SM. Functionalised N-Heterocyclic Carbene Ligands in Bimetallic Architectures. Chemistry 2020; 26:5927-5941. [PMID: 31981386 PMCID: PMC7317719 DOI: 10.1002/chem.201905510] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Indexed: 12/18/2022]
Abstract
N-Heterocyclic carbenes (NHCs) have become immensely successful ligands in coordination chemistry and homogeneous catalysis due to their strong terminal σ-donor properties. However, by targeting NHC ligands with additional functionalisation, a new area of NHC coordination chemistry has developed that has enabled NHCs to be used to build up bimetallic and multimetallic architectures. This minireview covers the development of functionalised NHC ligands that incorporate additional donor sites in order to coordinate two or more metal atoms. This can be through the N-atom of the NHC ring, through a donor group attached to the N-atom or the carbon backbone, coordination of the π-bond or an annulated π-donor on the backbone, or through direct metalation of the backbone.
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Affiliation(s)
- Kieren J. Evans
- Institute of Chemical SciencesHeriot-Watt UniversityEdinburghEH14 4ASUK
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6
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Herndon JW. The chemistry of the carbon-transition metal double and triple bond: Annual survey covering the year 2018. Coord Chem Rev 2019. [DOI: 10.1016/j.ccr.2019.213051] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Tashima N, Sawazaki T, Kayaki Y, Kuwata S. A P–C Chelate, Protic 1,2-Dihydropyridin-2-ylidene Ruthenium Complex: Synthesis, Structure, and Reversible Deprotonation. CHEM LETT 2019. [DOI: 10.1246/cl.190253] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Naoto Tashima
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 E4-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Taka Sawazaki
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 E4-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Yoshihito Kayaki
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 E4-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Shigeki Kuwata
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 E4-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
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Cepa S, Böhmer M, Roelfes F, Tan TTY, Dielmann F, Hahn FE. Homo- and Heterodinuclear Head-to-Head or Head-to-Tail Complexes of Rhodium(I) and Iridium(I) with C 2,N 3 or C 8,N 9 Bridging Azolato Ligands. Organometallics 2019. [DOI: 10.1021/acs.organomet.9b00074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Steffen Cepa
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 30, D-48149 Münster, Germany
| | - Maximilian Böhmer
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 30, D-48149 Münster, Germany
| | - Florian Roelfes
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 30, D-48149 Münster, Germany
| | - Tristan Tsai Yuan Tan
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 30, D-48149 Münster, Germany
| | - Fabian Dielmann
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 30, D-48149 Münster, Germany
| | - F. Ekkehardt Hahn
- Institut für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 30, D-48149 Münster, Germany
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