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Nussbaum BC, Cavicchi CR, Smith MD, Pellechia PJ, Peryshkov DV. Redox-Active Carboranyl Diphosphine as an Electron and Proton Transfer Agent. Inorg Chem 2024. [PMID: 39067032 DOI: 10.1021/acs.inorgchem.4c02022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/30/2024]
Abstract
In this work, we report the first example of the PCET reactivity for a boron cluster compound, the zwitterionic nido-carboranyl diphosphonium derivative 7-P(H)tBu2-10-P(H)iPr2-nido-C2B10H10. This main-group reagent efficiently transfers two electrons and two protons to quinones to yield hydroquinones and regenerate a neutral closo-carboranyl diphosphine, 1-PtBu2-2-PiPr2-closo-C2B10H10. As we have previously reported the conversion of this closo-carboranyl diphosphine into the zwitterionic nido- derivative upon reaction with main group hydrides, the transformation reported herein represents a complete synthetic cycle for the metal-free reduction of quinones, with the redox-active carboranyl diphosphine scaffold acting as a mediator. The proposed mechanism of this reduction, based on pKa determination, electrochemical studies, and kinetic isotope effect determination, involves the electron transfer from the nido- cluster to the quinone coupled with the delivery of protons.
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Affiliation(s)
- Bryce C Nussbaum
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter St, Columbia, South Carolina 29208, United States
| | - Cameron R Cavicchi
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter St, Columbia, South Carolina 29208, United States
| | - Mark D Smith
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter St, Columbia, South Carolina 29208, United States
| | - Perry J Pellechia
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter St, Columbia, South Carolina 29208, United States
| | - Dmitry V Peryshkov
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter St, Columbia, South Carolina 29208, United States
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2
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Ready AD, Nelson YA, Torres Pomares DF, Spokoyny AM. Redox-Active Boron Clusters. Acc Chem Res 2024; 57:1310-1324. [PMID: 38619089 DOI: 10.1021/acs.accounts.4c00040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
ConspectusIn this Account, we discuss our group's research over the past decade on a class of functionalized boron clusters with tunable chemical and physical properties, with an emphasis on accessing and controlling their redox behavior. These clusters can be thought of as three-dimensional aromatic systems that have distinct redox behavior and photophysical properties compared to their two-dimensional organic counterparts. Specifically, our lab has studied the highly tunable, multielectron redox behavior of B12(OR)12 clusters and applied these molecules in various settings. We first discuss the spectroscopic and electrochemical characterization of B12(OR)12 clusters in various oxidation states, followed by their use as catholytes and/or anolytes in redox flow batteries and chemical dopants in conjugated polymers. Additionally, the high oxidizing potential and visible light-absorbing nature of fluoroaryl-functionalized B12(OR)12 clusters have been leveraged by our group to generate weakly coordinating, photoexcitable species that can promote photooxidation chemistry.We have further translated these solution-phase studies of B12(OR)12 clusters to the solid state by using the precursor [B12(OH)12]2- cluster as a robust building block for hybrid metal oxide materials. Specifically, we have shown that the boron cluster can act as a thermally stable cross-linking material, which enhances electron transport between metal oxide nanoparticles. We applied this structural motif to create TiO2- and WO3-containing materials that showed promising properties as photocatalysts and electroactive materials for supercapacitors. Building on this concept, we later discovered that B12(OCH3)12, the smallest of the B12(OR)12 family, could retain its redox behavior in the solid state, a previously unseen phenomenon. We successfully harnessed this unique behavior for solid-state energy storage by implementing this boron cluster as a cathode-active material in a Li-ion prototype cell device. Recently, our group has also explored how to tune the redox properties of clusters other than B12(OR)12 species by synthesizing a library of vertex-differentiated clusters containing both B-OR and B-halogen groups. Due to the additive qualities of different functional groups on the cluster, these species allow access to a region of electrochemical potentials previously inaccessible by fully substituted closo-dodecaborate alkoxy-based derivatives.Lastly, we discuss our research into smaller-sized redox-active polyhedral boranes (B6- and B10-based cluster cores). Interestingly, these clusters show significantly less redox stability and reversibility than their dodecaborate-based counterparts. While exploring the functionalization of closo-hexaborate to create fully substituted derivates (i.e., [B6R6Hfac]-), we observed unique oxidative decomposition pathways for this cluster system. Consequently, we leveraged this oxidative instability to generate useful alkyl boronate esters via selective chemical oxidation. We further explored a closo-decaborate cluster as a platform to access electrophilic [B10H13]+ species capable of directly borylating arene compounds with unique regioselectivity. Upon chemical oxidation of the arylated decaborate clusters, we successfully synthesized various aryl boronate esters, establishing the generality of the oxidative cluster deconstruction concept.Overall, our work shows that boron clusters are an appealing class of redox-active molecules, and this fundamental and understudied property can be leveraged for constructing novel materials with tunable physical and electrochemical properties, as well as producing unique chemical reagents for small molecule synthesis.
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Affiliation(s)
- Austin D Ready
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095, United States
| | - Yessica A Nelson
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095, United States
| | - Daniel F Torres Pomares
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095, United States
| | - Alexander M Spokoyny
- Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California 90095, United States
- California NanoSystems Institute (CNSI), University of California, Los Angeles, 570 Westwood Plaza, Los Angeles, California 90095, United States
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Jeong D, Lee Y, Lee Y, Kim K, Cho J. Synthesis, Characterization, and Reactivity of a Highly Oxidative Mononuclear Manganese(IV)-Bis(Fluoro) Complex. J Am Chem Soc 2024; 146:4172-4177. [PMID: 38311844 DOI: 10.1021/jacs.3c13324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2024]
Abstract
Recently, transition-metal terminal nonoxo complexes have shown a remarkable ability to activate and functionalize C-H bonds via proton-coupled electron transfer (PCET). Here we report the first example of a mononuclear manganese(IV) bis(fluoro) complex bearing a tetradentate pyridinophane ligand, [MnIV(TBDAP)(F)2]2+ (3), with an X-ray single crystal structure and physicochemical characterization. The manganese(IV) bis(fluoro) complex has a very high reduction potential of 1.61 V vs SCE, thereby enabling the four-electron oxidation of mesitylene to 3,5-dimethylbenzaldehyde. Kinetic studies, including the kinetic isotope effect and employment of other toluene derivatives, reveal the electron transfer (ET)-driven PCET in the C-H bond activation of mesitylene by 3. This novel metal halide intermediate would be prominently valuable for expanding transition-metal halide chemistry.
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Affiliation(s)
- Donghyun Jeong
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Yujeong Lee
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Yuri Lee
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Kyungmin Kim
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Jaeheung Cho
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
- Graduate School of Carbon Neutrality, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
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Nussbaum BC, Humphries AL, Gange GB, Peryshkov DV. Redox-active carborane clusters in bond activation chemistry and ligand design. Chem Commun (Camb) 2023; 59:9918-9928. [PMID: 37522167 DOI: 10.1039/d3cc03011c] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/01/2023]
Abstract
Icosahedral closo-dodecaboranes have the ability to accept two electrons, opening into a dianionic nido-cluster. This transformation can be utilized to store electrons, drive bond activation, or alter coordination to metal cations. In this feature article, we present cases for each of these applications, wherein the redox activity of carborane facilitates the generation of unique products. We highlight the effects of exohedral substituents on reactivity and the stability of the products through conjugation between the cluster and exohedral substituents. Futher, the utilization of the redox properties and geometry of carborane clusters in the ligand design is detailed, both in the stabilization of low-valent complexes and in the tuning of ligand geometry.
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Affiliation(s)
- Bryce C Nussbaum
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter St, Columbia, South Carolina 29208, USA.
| | - Amanda L Humphries
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter St, Columbia, South Carolina 29208, USA.
| | - Gayathri B Gange
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter St, Columbia, South Carolina 29208, USA.
| | - Dmitry V Peryshkov
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter St, Columbia, South Carolina 29208, USA.
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Gange GB, Humphries AL, Royzman DE, Smith MD, Peryshkov DV. Metal-Free Bond Activation by Carboranyl Diphosphines. J Am Chem Soc 2021; 143:10842-10846. [PMID: 34254787 DOI: 10.1021/jacs.1c05387] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We report metal-free bond activation by the carboranyl diphosphine 1-PtBu2-2-PiPr2-C2B10H10. This main group element system contains basic binding sites and possesses the ability to cycle through two-electron redox states. The reported reactions with selected main group hydrides and alcohols occur via the formal oxidation of the phosphine groups and concomitant reduction of the boron cage. These transformations, which are driven by the cooperation between the electron-donating exohedral substituents and the electron-accepting cluster, differ from those of "regular" phosphines and are reminiscent of oxidative addition to transition metal centers, thus representing a new approach to metal-free bond activation.
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Affiliation(s)
- Gayathri B Gange
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter Street, Columbia, South Carolina 29208, United States
| | - Amanda L Humphries
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter Street, Columbia, South Carolina 29208, United States
| | - Dmitry E Royzman
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter Street, Columbia, South Carolina 29208, United States
| | - Mark D Smith
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter Street, Columbia, South Carolina 29208, United States
| | - Dmitry V Peryshkov
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter Street, Columbia, South Carolina 29208, United States
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Krebs J, Haehnel M, Krummenacher I, Friedrich A, Braunschweig H, Finze M, Ji L, Marder TB. Synthesis and Structure of an o-Carboranyl-Substituted Three-Coordinate Borane Radical Anion. Chemistry 2021; 27:8159-8167. [PMID: 33769625 PMCID: PMC8252506 DOI: 10.1002/chem.202100938] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Indexed: 12/14/2022]
Abstract
Bis(1-(4-tolyl)-carboran-2-yl)-(4-tolyl)-borane [(1-(4-MeC6 H4 )-closo-1,2-C2 B10 H10 -2-)2 (4-MeC6 H4 )B] (1), a new bis(o-carboranyl)-(R)-borane was synthesised by lithiation of the o-carboranyl precursor and subsequent salt metathesis reaction with (4-tolyl)BBr2 . Cyclic voltammetry experiments on 1 show multiple distinct reduction events with a one-electron first reduction. In a selective reduction experiment the corresponding paramagnetic radical anion 1.- was isolated and characterized. Single-crystal structure analyses allow an in-depth comparison of 1, 1.- , their calculated geometries, and the S1 excited state of 1. Photophysical studies of 1 show a charge transfer (CT) emission with low quantum yield in solution but a strong increase in the solid state. TD-DFT calculations were used to identify transition-relevant orbitals.
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Affiliation(s)
- Johannes Krebs
- Institute for Inorganic ChemistryInstitute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Martin Haehnel
- Institute for Inorganic ChemistryInstitute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Ivo Krummenacher
- Institute for Inorganic ChemistryInstitute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Alexandra Friedrich
- Institute for Inorganic ChemistryInstitute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Holger Braunschweig
- Institute for Inorganic ChemistryInstitute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Maik Finze
- Institute for Inorganic ChemistryInstitute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Lei Ji
- Frontiers Science Center for Flexible Electronics (FSCFE)Shaanxi Institute of Flexible Electronics (SIFE)Northwestern Polytechnical University127 West Youyi Road710072Xi'anP. R. China
| | - Todd B. Marder
- Institute for Inorganic ChemistryInstitute for Sustainable Chemistry & Catalysis with BoronJulius-Maximilians-Universität WürzburgAm Hubland97074WürzburgGermany
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