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Cheng Y, Huh DN, Tonks IA. Mechanistic study of pyrazole synthesis via oxidation-induced N-N coupling of diazatitanacycles. Dalton Trans 2024; 53:9510-9515. [PMID: 38767913 DOI: 10.1039/d4dt01412j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Metal-mediated inner-sphere N-N coupling is an uncommon route to N-N bond formation. Herein, we report a mechanistic study of pyrazole formation via oxidation-induced N-N coupling of diazatitanacycles. In TEMPO oxidation reactions, the first of two oxidations is rate limiting and TEMPO coordination to Ti is critical for reactivity. In oxidations with Fc+ salts, coordinating counteranions such (eg. Cl-) aid an "inner-sphere-like" oxidation.
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Affiliation(s)
- Yukun Cheng
- Department of Chemistry and Chemical Biology, Cornell University, 365 Spencer T. Olin Research Wing, Ithaca, New York, USA
| | - Daniel N Huh
- Department of Chemistry, University of Rhode Island, Kingston, Rhode Island, USA
| | - Ian A Tonks
- Department of Chemistry, University of Minnesota, 207 Pleasant St SE, Minneapolis, Minnesota, USA.
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2
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May AM, Dempsey JL. A new era of LMCT: leveraging ligand-to-metal charge transfer excited states for photochemical reactions. Chem Sci 2024; 15:6661-6678. [PMID: 38725519 PMCID: PMC11079626 DOI: 10.1039/d3sc05268k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 04/02/2024] [Indexed: 05/12/2024] Open
Abstract
Ligand-to-metal charge transfer (LMCT) excited states are capable of undergoing a wide array of photochemical reactions, yet receive minimal attention compared to other charge transfer excited states. This work provides general criteria for designing transition metal complexes that exhibit low energy LMCT excited states and routes to drive photochemistry from these excited states. General design principles regarding metal identity, oxidation state, geometry, and ligand sets are summarized. Fundamental photoreactions from these states including visible light-induced homolysis, excited state electron transfer, and other photoinduced chemical transformations are discussed and key design principles for enabling these photochemical reactions are further highlighted. Guided by these fundamentals, this review outlines critical considerations for the future design and application of coordination complexes with LMCT excited states.
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Affiliation(s)
- Ann Marie May
- Department of Chemistry, University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599-3290 USA
| | - Jillian L Dempsey
- Department of Chemistry, University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599-3290 USA
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3
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Gao S, Cui Z, Li F. Doublet-emissive materials for organic light-emitting diodes: exciton formation and emission processes. Chem Soc Rev 2023; 52:2875-2885. [PMID: 37052349 DOI: 10.1039/d2cs00772j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
Doublet-emission is mainly discovered in stable radicals, lanthanide-metal complexes with an f1 electron configuration and transition-metal complexes with a low-spin d5 electron configuration, and has a distinct radiation mechanism from closed-shell luminescent molecules and thus technology opportunities. There exists an unpaired electron in the frontier molecular orbitals which enables efficient nanosecond-scale luminescence in these materials due to the spin-allowed transitions between doublet-spin states. In this review, we summarize recent advances in these materials and their application in organic light emitting diodes (OLEDs). The photoluminescence and electroluminescence mechanisms of different doublet-emissive molecular systems are discussed, in addition to the photophysical phenomena arising from doublet states. We also outline the current challenges faced by each molecular system, and the potential outlook on the future research trends in this field.
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Affiliation(s)
- Shengxiang Gao
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China.
| | - Zhiyuan Cui
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China.
| | - Feng Li
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China.
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Rodriguez TM, Deegbey M, Chen CH, Jakubikova E, Dempsey JL. Isocyanide Ligands Promote Ligand-to-Metal Charge Transfer Excited States in a Rhenium(II) Complex. Inorg Chem 2023; 62:6576-6585. [PMID: 36652699 DOI: 10.1021/acs.inorgchem.2c03193] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A metal-to-ligand charge transfer with mixed intraligand character is observed for the rhenium hexakisarylisocyanide complex [Re(CNAr)6]PF6 (CNAr = 2,6-dimethylphenylisocyanide, λmax = 300 nm). Upon oxidation to [Re(CNAr)6](PF6)2, the dominant low energy optical transition is a ligand-to-metal charge transfer (LMCT) mixed with intraligand transitions (λmax = 650 nm). TD-DFT was used to identify the participating ligand-based orbitals in the LMCT transition, revealing that the majority of the donor orbital is based on the aryl ring (85%) as opposed to the CN bond (14%). For both [Re(CNAr)6]+ and [Re(CNAr)6]2+, structural characterization by X-ray diffraction reveals deviations from Oh geometry at the central Re ion, with larger reduction in symmetry observed for Re(II). For [Re(CNAr)6]+, these structural changes lead to a broadening of the strong ν(C≡N) stretch (2065 cm-1), as the degeneracy of the T1u IR-active mode is broken. Furthermore, a shoulder is observed for this ν(C≡N) stretch, resulting from deviation of the C-N-Ar bond from linearity. By contrast, [Re(CNAr)6]2+ has two weak bands in the ν(C≡N) region (2065 and 2121 cm-1). DFT calculations indicate that reduction of symmetry at the central rhenium ion manifests in the decrease in intensity and the observed split of the ν(C≡N) band. Stability of both complexes are limited by light-induced decomposition where Re(I) dissociates a isocyanide ligand upon irradiation and Re(II) absorbance decays under ambient light. These data provide new insights to the electronic structure of [Re(CNAr)6]2+, enhancing our understanding of LMCT excited states and the versatility of isocyanide ligands.
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Affiliation(s)
- Tayliz M Rodriguez
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Mawuli Deegbey
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Chun-Hsing Chen
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Elena Jakubikova
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Jillian L Dempsey
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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Rodriguez TM, Deegbey M, Jakubikova E, Dempsey JL. The ligand-to-metal charge transfer excited state of [Re(dmpe) 3] 2. PHOTOSYNTHESIS RESEARCH 2022; 151:155-161. [PMID: 34258679 DOI: 10.1007/s11120-021-00859-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 06/24/2021] [Indexed: 06/13/2023]
Abstract
The ligand-to-metal charge transfer (LMCT) transitions of [Re(dmpe)3]2+ (dmpe = bis-1,2-(dimethylphosphino)ethane) were interrogated using UV/Vis absorbance spectroscopy, photoluminescence spectroscopy, and time-dependent density functional theory. The solvent dependence of the lowest energy charge transfer transition was quantified; no solvatochromism was observed. TD-DFT calculations reveal the dominant LMCT transition is highly symmetric and delocalized involving all phopshine ligand donors in the charge transfer, providing an understanding for the absence of solvatochromism of [Re(dmpe)3]2+.
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Affiliation(s)
- Tayliz M Rodriguez
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3290, USA
| | - Mawuli Deegbey
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina, 27695, USA
| | - Elena Jakubikova
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina, 27695, USA
| | - Jillian L Dempsey
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-3290, USA.
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Bauer EB, Jurkowski K. Ferrocenium Ions as Catalysts: Decomposition Studies and Counteranion Influence on Catalytic Activity. SYNTHESIS-STUTTGART 2021. [DOI: 10.1055/s-0040-1705992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
AbstractCatalyst decomposition has a negative effect on catalytic activity, and knowledge of decomposition pathways can assist with catalyst development. Ferrocenium cations have been employed as catalysts in a number of organic transformations, and we investigated the stability of a number of ferrocenium salts in solution. The observed rate decomposition constants for [Fc]Cl, [Fc]PF6, [Fc]BF4, [Fc]CSA [Fc = ferrocenium, CSA = camphor-10-sulfonate (β)], [AcFc]SbF6, (AcFc = acetylated ferrocene), and [FcB(OH)2]SbF6 [FcB(OH)2 = ferrocenylboronic acid] were determined in CH2Cl2 solution by time-resolved UV-vis spectroscopy. The rate decomposition constants depended on the nature of the counterion, with [Fc]Cl being the most stable complex in solution. The decomposition rate constants dropped by roughly an order of magnitude in most cases when the experiments were performed in nitrogenated solvent, demonstrating that the decomposition is mainly an oxidative process. The cosolvent HFIP (1,1,1,3,3,3-hexafluoropropan-2-ol) slowed the decomposition of the ferrocenium cations as well. Many catalytic or stoichiometric reactions of ferrocenium cations are performed with alcohols; we determined that hexan-1-ol is decomposed over the course of 16 hours, but not oxidized in the presence of a ferrocenium cation. Finally, the different ferrocenium cations were employed in a test reaction to determine catalytic activity. The nucleophilic substitution of hydroxyl groups in a tertiary propargylic alcohol by an alcohol is catalyzed by all complexes, and, again, a counterion dependency of the catalytic activity was observed. Also, HFIP increases the catalytic activity of the ferrocenium cations. The research has importance in the development of ferrocenium-based catalyst systems, because changes in the counterion as well as the architecture of the ferrocenium cation have an influence on stability and catalytic activity.
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Chábera P, Lindh L, Rosemann NW, Prakash O, Uhlig J, Yartsev A, Wärnmark K, Sundström V, Persson P. Photofunctionality of iron(III) N-heterocyclic carbenes and related d transition metal complexes. Coord Chem Rev 2021. [DOI: 10.1016/j.ccr.2020.213517] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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9
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Photophysics and Photochemistry of Iron Carbene Complexes for Solar Energy Conversion and Photocatalysis. Catalysts 2020. [DOI: 10.3390/catal10030315] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Earth-abundant first row transition metal complexes are important for the development of large-scale photocatalytic and solar energy conversion applications. Coordination compounds based on iron are especially interesting, as iron is the most common transition metal element in the Earth’s crust. Unfortunately, iron-polypyridyl and related traditional iron-based complexes generally suffer from poor excited state properties, including short excited-state lifetimes, that make them unsuitable for most light-driven applications. Iron carbene complexes have emerged in the last decade as a new class of coordination compounds with significantly improved photophysical and photochemical properties, that make them attractive candidates for a range of light-driven applications. Specific aspects of the photophysics and photochemistry of these iron carbenes discussed here include long-lived excited state lifetimes of charge transfer excited states, capabilities to act as photosensitizers in solar energy conversion applications like dye-sensitized solar cells, as well as recent demonstrations of promising progress towards driving photoredox and photocatalytic processes. Complementary advances towards photofunctional systems with both Fe(II) complexes featuring metal-to-ligand charge transfer excited states, and Fe(III) complexes displaying ligand-to-metal charge transfer excited states are discussed. Finally, we outline emerging opportunities to utilize the improved photochemical properties of iron carbenes and related complexes for photovoltaic, photoelectrochemical and photocatalytic applications.
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Kimata H, Mochida T. Phase transitions and crystal structures of organometallic ionic plastic crystals comprised of ferrocenium cations and CH2BrBF3 anions. J Organomet Chem 2019. [DOI: 10.1016/j.jorganchem.2019.05.021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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11
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Aldrich KE, Billow BS, Staples RJ, Odom AL. Phosphine interactions with high oxidation state metals. Polyhedron 2019. [DOI: 10.1016/j.poly.2018.11.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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12
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Adams RE, Grusenmeyer TA, Griffith AL, Schmehl RH. Transition metal hydride complexes as mechanistic models for proton reduction catalysis. Coord Chem Rev 2018. [DOI: 10.1016/j.ccr.2018.02.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Tseng TW, Mendiratta S, Luo TT, Chen TW, Lee YP. A new route to constructing rhenium(I)-based 8-hydroxyquinolate complexes: Synthesis, structures and luminescent properties. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2018.02.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Neary MC, Quinlivan PJ, Parkin G. Zerovalent Nickel Compounds Supported by 1,2-Bis(diphenylphosphino)benzene: Synthesis, Structures, and Catalytic Properties. Inorg Chem 2017; 57:374-391. [DOI: 10.1021/acs.inorgchem.7b02636] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Michelle C. Neary
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Patrick J. Quinlivan
- Department of Chemistry, Columbia University, New York, New York 10027, United States
| | - Gerard Parkin
- Department of Chemistry, Columbia University, New York, New York 10027, United States
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16
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MacInnis MC, DeMott JC, Zolnhofer EM, Zhou J, Meyer K, Hughes RP, Ozerov OV. Cationic Two-Coordinate Complexes of Pd(I) and Pt(I) Have Longer Metal-Ligand Bonds Than Their Neutral Counterparts. Chem 2016. [DOI: 10.1016/j.chempr.2016.11.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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17
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Chan KW, Bai W, Lee KF, Lee KH, Sung HHY, Williams ID, Lin Z, Jia G. Synthesis of Rhenium Vinylidene and Carbyne Complexes from Reactions of [Re(dppm)3]I with Terminal Alkynes and Alkynols. Organometallics 2016. [DOI: 10.1021/acs.organomet.6b00568] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ka Wing Chan
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People’s Republic of China
| | - Wei Bai
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People’s Republic of China
| | - Kui Fun Lee
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People’s Republic of China
| | - Ka-Ho Lee
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People’s Republic of China
| | - Herman H. Y. Sung
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People’s Republic of China
| | - Ian D. Williams
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People’s Republic of China
| | - Zhenyang Lin
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People’s Republic of China
| | - Guochen Jia
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People’s Republic of China
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Zhang Y, Petersen JL, Milsmann C. A Luminescent Zirconium(IV) Complex as a Molecular Photosensitizer for Visible Light Photoredox Catalysis. J Am Chem Soc 2016; 138:13115-13118. [PMID: 27643820 DOI: 10.1021/jacs.6b05934] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yu Zhang
- C. Eugene
Bennett Department
of Chemistry, West Virginia University, 100 Prospect Street, Morgantown, West Virginia 26506, United States
| | - Jeffrey L. Petersen
- C. Eugene
Bennett Department
of Chemistry, West Virginia University, 100 Prospect Street, Morgantown, West Virginia 26506, United States
| | - Carsten Milsmann
- C. Eugene
Bennett Department
of Chemistry, West Virginia University, 100 Prospect Street, Morgantown, West Virginia 26506, United States
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