1
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Cooney S, Walls MRA, Schreiber E, Brennessel WW, Matson EM. Heterometal Dopant Changes the Mechanism of Proton-Coupled Electron Transfer at the Polyoxovanadate-Alkoxide Surface. J Am Chem Soc 2024; 146:2364-2369. [PMID: 38241170 PMCID: PMC10835708 DOI: 10.1021/jacs.3c14054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 01/21/2024]
Abstract
The transfer of two H-atom equivalents to the titanium-doped polyoxovanadate-alkoxide, [TiV5O6(OCH3)13], results in the formation of a V(III)-OH2 site at the surface of the assembly. Incorporation of the group (IV) metal ion results in a weakening of the O-H bonds of [TiV5O5(OH2)(OCH3)13] in comparison to its homometallic congener, [V6O6(OH2)(OCH3)12], resembling more closely the thermodynamics reported for the one-electron reduced derivative, [V6O6(OH2)(OCH3)12]1-. An analysis of early time points of the reaction of [TiV5O6(OCH3)13] and 5,10-dihydrophenazine reveals the formation of an oxidized substrate, suggesting that proton-coupled electron transfer proceeds via initial electron transfer from substrate to cluster prior to proton transfer. These results demonstrate the profound influence of heterometal dopants on the mechanism of PCET with respect to the surface of the assembly.
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Affiliation(s)
- Shannon
E. Cooney
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - M. Rebecca A. Walls
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - Eric Schreiber
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - William W. Brennessel
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
| | - Ellen M. Matson
- Department of Chemistry, University
of Rochester, Rochester, New York 14627, United States
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2
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Schreiber E, Brennessel WW, Matson EM. Regioselectivity of concerted proton-electron transfer at the surface of a polyoxovanadate cluster. Chem Sci 2023; 14:1386-1396. [PMID: 36794190 PMCID: PMC9906639 DOI: 10.1039/d2sc05928b] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 12/19/2022] [Indexed: 01/19/2023] Open
Abstract
Proton-coupled electron transfer (PCET) is an important process in the activation and reactivity of metal oxide surfaces. In this work, we study the electronic structure of a reduced polyoxovanadate-alkoxide cluster bearing a single bridging oxide moiety. The structural and electronic implications of the incorporation of bridging oxide sites are revealed, most notably resulting in the quenching of cluster-wide electron delocalization in the most reduced state of the molecule. We correlate this attribute to a change in regioselectivity of PCET to the cluster surface (e.g. reactivity at terminal vs. bridging oxide groups). Reactivity localized at the bridging oxide site enables reversible storage of a single H-atom equivalent, changing the stoichiometry of PCET from a 2e-/2H+ process. Kinetic investigations indicate that the change in site of reactivity translates to an accelerated rate of e-/H+ transfer to the cluster surface. Our work summarizes the role which electronic occupancy and ligand density play in the uptake of e-/H+ pairs at metal oxide surfaces, providing design criteria for functional materials for energy storage and conversion processes.
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Affiliation(s)
- Eric Schreiber
- Department of Chemistry, University of Rochester Rochester NY 14611 USA
| | | | - Ellen M Matson
- Department of Chemistry, University of Rochester Rochester NY 14611 USA
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3
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Breibeck J, Gumerova NI, Rompel A. Oxo-Replaced Polyoxometalates: There Is More than Oxygen. ACS ORGANIC & INORGANIC AU 2022; 2:477-495. [PMID: 36510613 PMCID: PMC9732882 DOI: 10.1021/acsorginorgau.2c00014] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 08/10/2022] [Accepted: 08/10/2022] [Indexed: 02/02/2023]
Abstract
The presence of oxo-ligands is one of the main required characteristics for polyoxometalates (POMs), although some oxygen ions in a metallic environment can be replaced by other nonmetals, while maintaining the POM structure. The replacement of oxo-ligands offers a valuable approach to tune the charge distribution and connected properties like reducibility and hydrolytic stability of POMs for the development of tailored compounds. By assessing the reported catalytic and biological applications and connecting them to POM structures, the present review provides a guideline for synthetic approaches and aims to stimulate further applications where the oxo-replaced compounds are superior to their oxo-analogues. Oxo-replacement in POMs deserves more attention as a valuable tool to form chemically activated precursors for the synthesis of novel structures or to upgrade established structures with extraordinary properties for challenging applications.
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4
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Cooney SE, Fertig AA, Buisch MR, Brennessel WW, Matson EM. Coordination-induced bond weakening of water at the surface of an oxygen-deficient polyoxovanadate cluster. Chem Sci 2022; 13:12726-12737. [PMID: 36519047 PMCID: PMC9645371 DOI: 10.1039/d2sc04843d] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 10/10/2022] [Indexed: 10/19/2023] Open
Abstract
Hydrogen-atom (H-atom) transfer at the surface of heterogeneous metal oxides has received significant attention owing to its relevance in energy conversion and storage processes. Here, we present the synthesis and characterization of an organofunctionalized polyoxovanadate cluster, (calix)V6O5(OH2)(OMe)8 (calix = 4-tert-butylcalix[4]arene). Through a series of equilibrium studies, we establish the BDFE(O-H)avg of the aquo ligand as 62.4 ± 0.2 kcal mol-1, indicating substantial bond weaking of water upon coordination to the cluster surface. Subsequent kinetic isotope effect studies and Eyring analysis indicate the mechanism by which the hydrogenation of organic substrates occurs proceeds through a concerted proton-electron transfer from the aquo ligand. Atomistic resolution of surface reactivity presents a novel route of hydrogenation reactivity from metal oxide surfaces through H-atom transfer from surface-bound water molecules.
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Affiliation(s)
- Shannon E Cooney
- Department of Chemistry, University of Rochester Rochester NY 14627 USA
| | - Alex A Fertig
- Department of Chemistry, University of Rochester Rochester NY 14627 USA
| | | | | | - Ellen M Matson
- Department of Chemistry, University of Rochester Rochester NY 14627 USA
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5
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Schreiber E, Brennessel WW, Matson EM. Charge-State Dependence of Proton Uptake in Polyoxovanadate-alkoxide Clusters. Inorg Chem 2022; 61:4789-4800. [PMID: 35293218 PMCID: PMC8965876 DOI: 10.1021/acs.inorgchem.1c02937] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Indexed: 11/29/2022]
Abstract
Here, we present an investigation of the thermochemistry of proton uptake in acetonitrile across three charge states of a polyoxovanadate-alkoxide (POV-alkoxide) cluster, [V6O7(OMe)12]n (n = 2-, 1-, and 0). The vanadium oxide assembly studied features bridging sites saturated by methoxide ligands, isolating protonation to terminal vanadyl moieties. Exposure of [V6O7(OMe)12]n to organic acids of appropriate strength results in the protonation of a terminal V═O bond, generating the transient hydroxide-substituted POV-alkoxide cluster [V6O6(OH)(OMe)12]n+1. Evidence for this intermediate proved elusive in our initial report, but here we present the isolation of a divalent anionic cluster that features hydrogen bonding to dimethylammonium at the terminal oxo site. Degradation of the protonated species results in the formation of equimolar quantities of one-electron-oxidized and oxygen-atom-efficient complexes, [V6O7(OMe)12]n+1 and [V6O6(OMe)12]n+1. While analogous reactivity was observed across the three charge states of the cluster, a dependence on the acid strength was observed, suggesting that the oxidation state of the vanadium oxide assembly influences the basicity of the cluster surface. Spectroscopic investigations reveal sigmoidal relationships between the acid strength and cluster conversion across the redox series, allowing for determination of the proton affinity of the surface of the cluster in all three charge states. The fully reduced cluster is found to be the most basic, with higher oxidation states of the assembly possessing substantially reduced proton affinities (∼7 pKa units per electron). These results further our understanding of the site-specific reactivity of terminal M═O bonds with protons in an organic solvent, revealing design criteria for engineering functional surfaces of metal oxide materials of relevance to energy storage and conversion.
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Affiliation(s)
- Eric Schreiber
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - William W. Brennessel
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Ellen M. Matson
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
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6
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Schreiber E, Fertig AA, Brennessel WW, Matson EM. Oxygen-Atom Defect Formation in Polyoxovanadate Clusters via Proton-Coupled Electron Transfer. J Am Chem Soc 2022; 144:5029-5041. [PMID: 35275632 PMCID: PMC8949770 DOI: 10.1021/jacs.1c13432] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Indexed: 11/28/2022]
Abstract
The uptake of hydrogen atoms (H-atoms) into reducible metal oxides has implications in catalysis and energy storage. However, outside of computational modeling, it is difficult to obtain insight into the physicochemical factors that govern H-atom uptake at the atomic level. Here, we describe oxygen-atom vacancy formation in a series of hexavanadate assemblies via proton-coupled electron transfer, presenting a novel pathway for the formation of defect sites at the surface of redox-active metal oxides. Kinetic investigations reveal that H-atom transfer to the metal oxide surface occurs through concerted proton-electron transfer, resulting in the formation of a transient VIII-OH2 moiety that, upon displacement of the water ligand with an acetonitrile molecule, forms the oxygen-deficient polyoxovanadate-alkoxide cluster. Oxidation state distribution of the cluster core dictates the affinity of surface oxido ligands for H-atoms, mirroring the behavior of reducible metal oxide nanocrystals. Ultimately, atomistic insights from this work provide new design criteria for predictive proton-coupled electron-transfer reactivity of terminal M═O moieties at the surface of nanoscopic metal oxides.
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Affiliation(s)
| | | | - William W. Brennessel
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Ellen M. Matson
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
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7
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Chakraborty S, Schreiber E, Sanchez-Lievanos KR, Tariq M, Brennessel WW, Knowles KE, Matson EM. Modelling local structural and electronic consequences of proton and hydrogen-atom uptake in VO 2 with polyoxovanadate clusters. Chem Sci 2021; 12:12744-12753. [PMID: 34703561 PMCID: PMC8494032 DOI: 10.1039/d1sc02809j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Accepted: 08/24/2021] [Indexed: 11/21/2022] Open
Abstract
We report the synthesis and characterisation of a series of siloxide-functionalised polyoxovanadate-alkoxide (POV-alkoxide) clusters, [V6O6(OSiMe3)(OMe)12] n (n = 1-, 2-), that serve as molecular models for proton and hydrogen-atom uptake in vanadium dioxide, respectively. Installation of a siloxide moiety on the surface of the Lindqvist core was accomplished via addition of trimethylsilyl trifluoromethylsulfonate to the fully-oxygenated cluster [V6O7(OMe)12]2-. Characterisation of [V6O6(OSiMe3)(OMe)12]1- by X-ray photoelectron spectroscopy reveals that the incorporation of the siloxide group does not result in charge separation within the hexavanadate assembly, an observation that contrasts directly with the behavior of clusters bearing substitutional dopants. The reduced assembly, [V6O6(OSiMe3)(OMe)12]2-, provides an isoelectronic model for H-doped VO2, with a vanadium(iii) ion embedded within the cluster core. Notably, structural analysis of [V6O6(OSiMe3)(OMe)12]2- reveals bond perturbations at the siloxide-functionalised vanadium centre that resemble those invoked upon H-atom uptake in VO2 through ab initio calculations. Our results offer atomically precise insight into the local structural and electronic consequences of the installation of hydrogen-atom-like dopants in VO2, and challenge current perspectives of the operative mechanism of electron-proton co-doping in these materials.
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Affiliation(s)
| | - Eric Schreiber
- Department of Chemistry, University of Rochester Rochester NY 14627 USA
| | | | - Mehrin Tariq
- Department of Chemistry, University of Rochester Rochester NY 14627 USA
| | | | - Kathryn E Knowles
- Department of Chemistry, University of Rochester Rochester NY 14627 USA
| | - Ellen M Matson
- Department of Chemistry, University of Rochester Rochester NY 14627 USA
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8
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Meyer RL, Miró P, Brennessel WW, Matson EM. O 2 Activation with a Sterically Encumbered, Oxygen-Deficient Polyoxovanadate-Alkoxide Cluster. Inorg Chem 2021; 60:13833-13843. [PMID: 34161731 DOI: 10.1021/acs.inorgchem.1c00887] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The isolation of the oxygen-deficient, polyoxovanadate-alkoxide (POV-alkoxide) cluster, [nBu4N][V6O6(OMe)12(MeCN)], and its subsequent reactivity with oxygen (O2), has demonstrated the utility of these assemblies as molecular models for heterogeneous metal oxide catalysts. However, the mechanism through which this cluster activates and reduces O2 to generate the oxygenated species is poorly understood. Currently it is speculated that this POV-alkoxide mediates the four-electron O-O bond cleavage through an O2 bridged dimeric intermediate, a mechanism which is not viable for O2 reduction at solid-state metal oxide surfaces. Here, we report the successful activation and reduction of O2 by the calix-functionalized POV-alkoxide cluster, [nBu4N][(calix)V6O6(OMe)8](MeCN)] (calix = 4-tert-butylcalix[4]arene). The steric hindrance imparted to the open vanadium site by the calix motif eliminates the possibility of cooperative, bimolecular O2 activation, allowing for a comparison of the reactivity of this system with that of the nonfunctionalized POV-alkoxide described previously. Rigorous characterization of the calix-substituted assembly, enabled by its newfound solubility in organic solvent, reveals that the incorporation of the tetradentate aryloxide ligand into the POV-alkoxide scaffold perturbs the electronic communication between the site-differentiated vanadium(III) ion and the cluster core. Collectively, our results provide insight into the physiochemical factors that are important during the O2 reduction reaction at oxygen-deficient sites in reduced POV-alkoxide clusters.
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Affiliation(s)
- Rachel L Meyer
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Pere Miró
- Department of Chemistry, University of South Dakota, Vermillion, South Dakota 57069, United States
| | - William W Brennessel
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Ellen M Matson
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
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9
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Chakraborty S, Petel BE, Schreiber E, Matson EM. Atomically precise vanadium-oxide clusters. NANOSCALE ADVANCES 2021; 3:1293-1318. [PMID: 36132875 PMCID: PMC9419539 DOI: 10.1039/d0na00877j] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 01/19/2021] [Indexed: 05/08/2023]
Abstract
Polyoxovanadate (POV) clusters are an important subclass of polyoxometalates with a broad range of molecular compositions and physicochemical properties. One relatively underdeveloped application of these polynuclear assemblies involves their use as atomically precise, homogenous molecular models for bulk metal oxides. Given the structural and electronic similarities of POVs and extended vanadium oxide materials, as well as the relative ease of modifying the homogenous congeners, investigation of the chemical and physical properties of pristine and modified cluster complexes presents a method toward understanding the influence of structural modifications (e.g. crystal structure/phase, chemical makeup of surface ligands, elemental dopants) on the properties of extended solids. This review summarises recent advances in the use of POV clusters as atomically precise models for bulk metal oxides, with particular focus on the assembly of vanadium oxide clusters and the consequences of altering the molecular composition of the assembly via organofunctionalization and the incorporation of elemental "dopants".
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Affiliation(s)
| | - Brittney E Petel
- University of Rochester, Department of Chemistry Rochester NY 14627 USA
| | - Eric Schreiber
- University of Rochester, Department of Chemistry Rochester NY 14627 USA
| | - Ellen M Matson
- University of Rochester, Department of Chemistry Rochester NY 14627 USA
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10
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Chakraborty S, Matson EM. Reductive silylation of polyoxovanadate surfaces using Mashima's reagent. Inorg Chem Front 2021. [DOI: 10.1039/d1qi00920f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mechanistic insights into the reductive silylation of metal oxide surfaces.
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Affiliation(s)
- Sourav Chakraborty
- Department of Chemistry, University of Rochester, Rochester, NY 14627, USA
| | - Ellen M. Matson
- Department of Chemistry, University of Rochester, Rochester, NY 14627, USA
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11
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Fa Bamba I, Falaise C, Gbassi GK, Atheba P, Haouas M, Cadot E. N-tert-butoxycarbonyl (BOC) protected [V6O13{(OCH2)3CNH2}2]2−: synthesis, structural characterization, and solution behavior. J COORD CHEM 2020. [DOI: 10.1080/00958972.2020.1830074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Ibrahima Fa Bamba
- Institut Lavoisier de Versailles, CNRS, UVSQ, Université Paris-Saclay, Versailles, France
| | - Clément Falaise
- Institut Lavoisier de Versailles, CNRS, UVSQ, Université Paris-Saclay, Versailles, France
| | - Gildas K. Gbassi
- UFR Sciences Pharmaceutiques et Biologiques (UFR SPB), Université Félix Houphouet Boigny (UFHB), Abidjan, Côte d'Ivoire
| | - Patrick Atheba
- UFR Sciences Pharmaceutiques et Biologiques (UFR SPB), Université Félix Houphouet Boigny (UFHB), Abidjan, Côte d'Ivoire
| | - Mohamed Haouas
- Institut Lavoisier de Versailles, CNRS, UVSQ, Université Paris-Saclay, Versailles, France
| | - Emmanuel Cadot
- Institut Lavoisier de Versailles, CNRS, UVSQ, Université Paris-Saclay, Versailles, France
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12
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Petel BE, Matson EM. Physicochemical Factors That Influence the Deoxygenation of Oxyanions in Atomically Precise, Oxygen-Deficient Vanadium Oxide Assemblies. Inorg Chem 2020; 60:6855-6864. [DOI: 10.1021/acs.inorgchem.0c02052] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Brittney E. Petel
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Ellen M. Matson
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
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13
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Schreiber E, Petel BE, Matson EM. Acid-Induced, Oxygen-Atom Defect Formation in Reduced Polyoxovanadate-Alkoxide Clusters. J Am Chem Soc 2020; 142:9915-9919. [PMID: 32433883 DOI: 10.1021/jacs.0c03864] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Here, we present the first example of acid-induced, oxygen-atom abstraction from the surface of a polyoxometalate cluster. Generation of the oxygen-deficient vanadium oxide, [V6O6(OC2H5)12]1-, was confirmed via independent synthesis. Spectroscopic analysis using infrared and electronic absorption spectroscopies affords resolution of the electronic structure of the oxygen-deficient cluster (oxidation state distribution = [VIIIVIV5]). This work has direct implications toward the elucidation of possible mechanisms of acid-assisted vacancy formation in bulk transition metal oxides, in particular electron-proton codoping that has recently been described for vanadium oxide (VO2). Ultimately, these molecular models deepen our understanding of proton-dependent redox chemistry of transition metal oxide surfaces.
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Affiliation(s)
- Eric Schreiber
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Brittney E Petel
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Ellen M Matson
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
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14
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Maiola ML, Petel BE, Brennessel WW, Matson EM. Site-selective halogenation of mixed-valent vanadium oxide clusters. Dalton Trans 2020; 49:16184-16192. [PMID: 32307494 DOI: 10.1039/d0dt01077d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Here, we expand on the synthesis and characterization of chloride-functionalized polyoxovanadate-alkoxide (POV-alkoxide) clusters, to include the halogenation of mixed-valent vanadium oxide assemblies.
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15
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Petel BE, Matson EM. Oxygen-atom vacancy formation and reactivity in polyoxovanadate clusters. Chem Commun (Camb) 2020; 56:13477-13490. [DOI: 10.1039/d0cc05920j] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Overview of recent work detailing oxygen-deficient polyoxovanadate clusters as models for reducible metal oxides: toward gaining a fundamental understanding the consequences of vacancy formation on metal oxide surfaces during catalysis.
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16
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Petel BE, Meyer RL, Maiola ML, Brennessel WW, Müller AM, Matson EM. Site-Selective Halogenation of Polyoxovanadate Clusters: Atomically Precise Models for Electronic Effects of Anion Doping in VO2. J Am Chem Soc 2019; 142:1049-1056. [DOI: 10.1021/jacs.9b11874] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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17
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Petel BE, Meyer RL, Brennessel WW, Matson EM. Oxygen atom transfer with organofunctionalized polyoxovanadium clusters: O-atom vacancy formation with tertiary phosphanes and deoxygenation of styrene oxide. Chem Sci 2019; 10:8035-8045. [PMID: 31853359 PMCID: PMC6837047 DOI: 10.1039/c9sc02882j] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 07/13/2019] [Indexed: 12/22/2022] Open
Abstract
We report a rare example of oxygen atom transfer (OAT) from a polyoxometalate cluster to a series of tertiary phosphanes followed by OAT from styrene oxide to the reduced scaffold, resulting in the formation of styrene.
We report a rare example of oxygen atom transfer (OAT) from a polyoxometalate cluster to a series of tertiary phosphanes. Addition of PR3 (PR3 = PMe3, PMe2Ph, PMePh2, PPh3) to a neutral methoxide-bridged polyoxovanadate-alkoxide (POV-alkoxide) cluster, [V6O7(OMe)12]0, results in isolation of a reduced structure with phosphine oxide datively coordinated to a site-differentiated VIII ion. A positive correlation between the steric and electronic properties of the phosphane and the reaction rate was observed. Further investigation of the steric influence of the alkoxy-bridged clusters on OAT was probed through the use of POV clusters with bridging alkoxide ligands of varying chain length ([V6O7(OR′)12]; R′ = Et, nPr). These investigations expose that steric hinderance of the vanadyl moieties has significant influence on the rate of OAT. Finally, we report the reactivity of the reduced POV-alkoxide clusters with styrene oxide, resulting in the deoxygenation of the substrate to generate styrene. This result is the first example of epoxide deoxygenation using homometallic polyoxometalate clusters, demonstrating the potential for mono-vacant Lindqvist clusters to catalyze the removal of oxygen atoms from organic substrates.
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Affiliation(s)
- Brittney E Petel
- Department of Chemistry , University of Rochester , Rochester , New York 14627 , USA .
| | - Rachel L Meyer
- Department of Chemistry , University of Rochester , Rochester , New York 14627 , USA .
| | - William W Brennessel
- Department of Chemistry , University of Rochester , Rochester , New York 14627 , USA .
| | - Ellen M Matson
- Department of Chemistry , University of Rochester , Rochester , New York 14627 , USA .
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