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Ariafard A, Longhurst M, Swiegers GF, Stranger R. Mechanistic elucidation of O 2 production from tBuOOH in water using the Mn(II) catalyst [Mn 2(mcbpen) 2(H 2O) 2] 2+: a DFT study. Dalton Trans 2024; 53:14089-14097. [PMID: 39120522 DOI: 10.1039/d4dt01700e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2024]
Abstract
This study employs density functional theory at the SMD/B3LYP-D3/6-311+G(2d,p),def2-TZVPP//SMD/B3LYP-D3/6-31G(d),SDD level of theory to explore the mechanistic details of O2 generation from tBuOOH, using H218O as the solvent, in the presence of the Mn(II) catalyst [Mn2(mcbpen)2(H2O)2]2+. Since this chemistry was reported to occur through the reaction of Mn(III)(μ-O)Mn(IV)-O˙ with water, we first revaluated this proposal and found that it occurs with an activation barrier greater than 36 kcal mol-1, ruling out the functioning of such a dimer as the active catalyst. Experimental evidence has shown that the oxidation of [Mn2(mcbpen)2(H2O)2]2+ by tBuOOH in H218O produces the Mn(IV) species [Mn(18O)(mcbpen)]+. Our investigations revealed a plausible mechanism for this observation in which [Mn (18O)(mcbpen)]+ acts as the active catalyst, generating the tert-butyl peroxyl radical (tBuOO˙) through its reaction with tBuOOH. In this proposed mechanism, the O-O bond is formed through the interaction of tBuOO˙ with another [Mn(18O)(mcbpen)]+, finally leading to the formation of the 16O18O product. Our findings underscore the pivotal role of [Mn(18O)(mcbpen)]+ in both generating the active species tBuOO˙ and consuming it to produce 16O18O. With activation barriers as low as about 9 kcal mol-1, these elementary steps highlight the feasibility of our proposed mechanism. Moreover, this mechanism elucidates why, experimentally, one of the oxygen atoms in the released O2 comes from water, while the other originates from tBuOOH. This research broadens our understanding of high oxidation state manganese chemistry, setting the stage for the development of more efficient Mn-based catalysts, aimed at improving processes in both renewable energy and synthetic chemistry.
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Affiliation(s)
- Alireza Ariafard
- Research School of Chemistry, Australian National University, Canberra, Australia.
| | - Matthew Longhurst
- Intelligent Polymer Research Institute, University of Wollongong, Wollongong, Australia
| | - Gerhard F Swiegers
- Intelligent Polymer Research Institute, University of Wollongong, Wollongong, Australia
| | - Robert Stranger
- Research School of Chemistry, Australian National University, Canberra, Australia.
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Ariafard A, Longhurst M, Swiegers GF, Stranger R. Elucidating the catalytic mechanisms of O 2 generation by [Mn 2(μ-O) 2(terpy) 2(OH 2) 2] 3+ using DFT calculations: a focus on ClO - as oxidant. Dalton Trans 2024; 53:7580-7589. [PMID: 38616680 DOI: 10.1039/d4dt00734d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
The experimentally reported Mn(IV)Mn(III) complex [Mn2(μ-O)2(terpy)2(OH2)2]3+ has been observed catalyzing O2 generation with oxidants like ClO- and HSO5-. Previous mechanistic studies primarily focused on O2 generation with HSO5-, concluding that Mn(IV)Mn(III) acts as a catalyst, generating a Mn(IV)Mn(IV)-oxyl species as a key intermediate responsible for O-O bond formation. This computational study employs DFT calculations to investigate whether the catalytic generation of O2 using ClO- follows the same mechanism previously identified with HSO5- as the oxidant, or if it proceeds through an alternate pathway. To this end, we explored multiple pathways using ClO- as the oxidant. Interestingly, our findings confirm that in the case of ClO- as the oxidant, similar to what was observed with HSO5-, the Mn(IV)Mn(IV)-oxyl species indeed plays a crucial role in driving the catalytic evolution of O2 with the potential formation of the binuclear complexes Mn(IV)Mn(IV)-oxy and Mn(IV)Mn(IV)-OH during the reaction. These complexes are reactive in producing O2, with activation free energies of 15.9 and 14.3 kcal mol-1, respectively. However, our calculations revealed that the Mn(IV)Mn(IV)-oxyl complex is significantly more reactive in producing O2 than Mn(IV)Mn(IV)-oxy and Mn(IV)Mn(IV)-OH, with a lower free energy barrier of 8.1 kcal mol-1. Consequently, even though Mn(IV)Mn(IV)-oxyl is predicted to be present in much lower concentrations than Mn(IV)Mn(IV)-oxy and Mn(IV)Mn(IV)-OH, it emerges as the species acting as the active catalyst for catalytic O2 generation. This study enhances our knowledge of high oxidation state (+3 and +4) manganese chemistry, highlighting its key role in catalysis and paving the way for more efficient Mn-based catalysts with broad applications.
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Affiliation(s)
- Alireza Ariafard
- Research School of Chemistry, Australian National University, Canberra, Australia.
| | - Matthew Longhurst
- Intelligent Polymer Research Institute, University of Wollongong, Wollongong, Australia
| | - Gerhard F Swiegers
- Intelligent Polymer Research Institute, University of Wollongong, Wollongong, Australia
| | - Robert Stranger
- Research School of Chemistry, Australian National University, Canberra, Australia.
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A Review of Recent Developments in Molecular Dynamics Simulations of the Photoelectrochemical Water Splitting Process. Catalysts 2021. [DOI: 10.3390/catal11070807] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
In this review, we provide a short overview of the Molecular Dynamics (MD) method and how it can be used to model the water splitting process in photoelectrochemical hydrogen production. We cover classical non-reactive and reactive MD techniques as well as multiscale extensions combining classical MD with quantum chemical and continuum methods. Selected examples of MD investigations of various aqueous semiconductor interfaces with a special focus on TiO2 are discussed. Finally, we identify gaps in the current state-of-the-art where further developments will be needed for better utilization of MD techniques in the field of water splitting.
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Liao RZ, Siegbahn PEM. Quantum Chemical Modeling of Homogeneous Water Oxidation Catalysis. CHEMSUSCHEM 2017; 10:4236-4263. [PMID: 28875583 DOI: 10.1002/cssc.201701374] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 08/31/2017] [Indexed: 06/07/2023]
Abstract
The design of efficient and robust water oxidation catalysts has proven challenging in the development of artificial photosynthetic systems for solar energy harnessing and storage. Tremendous progress has been made in the development of homogeneous transition-metal complexes capable of mediating water oxidation. To improve the efficiency of the catalyst and to design new catalysts, a detailed mechanistic understanding is necessary. Quantum chemical modeling calculations have been successfully used to complement the experimental techniques to suggest a catalytic mechanism and identify all stationary points, including transition states for both O-O bond formation and O2 release. In this review, recent progress in the applications of quantum chemical methods for the modeling of homogeneous water oxidation catalysis, covering various transition metals, including manganese, iron, cobalt, nickel, copper, ruthenium, and iridium, is discussed.
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Affiliation(s)
- Rong-Zhen Liao
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Materials Chemistry and Service Failure, Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, P. R. China
| | - Per E M Siegbahn
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 10691, Stockholm, Sweden
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Vidossich P, Lledós A, Ujaque G. First-Principles Molecular Dynamics Studies of Organometallic Complexes and Homogeneous Catalytic Processes. Acc Chem Res 2016; 49:1271-8. [PMID: 27268523 DOI: 10.1021/acs.accounts.6b00054] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Computational chemistry is a valuable aid to complement experimental studies of organometallic systems and their reactivity. It allows probing mechanistic hypotheses and investigating molecular structures, shedding light on the behavior and properties of molecular assemblies at the atomic scale. When approaching a chemical problem, the computational chemist has to decide on the theoretical approach needed to describe electron/nuclear interactions and the composition of the model used to approximate the actual system. Both factors determine the reliability of the modeling study. The community dedicated much effort to developing and improving the performance and accuracy of theoretical approaches for electronic structure calculations, on which the description of (inter)atomic interactions rely. Here, the importance of the model system used in computational studies is highlighted through examples from our recent research focused on organometallic systems and homogeneous catalytic processes. We show how the inclusion of explicit solvent allows the characterization of molecular events that would otherwise not be accessible in reduced model systems (clusters). These include the stabilization of nascent charged fragments via microscopic solvation (notably, hydrogen bonding), transfer of charge (protons) between distant fragments mediated by solvent molecules, and solvent coordination to unsaturated metal centers. Furthermore, when weak interactions are involved, we show how conformational and solvation properties of organometallic complexes are also affected by the explicit inclusion of solvent molecules. Such extended model systems may be treated under periodic boundary conditions, thus removing the cluster/continuum (or vacuum) boundary, and require a statistical mechanics simulation technique to sample the accessible configurational space. First-principles molecular dynamics, in which atomic forces are computed from electronic structure calculations (namely, density functional theory), is certainly the technique of choice to investigate chemical events in solution. This methodology is well established and thanks to advances in both algorithms and computational resources simulation times required for the modeling of chemical events are nowadays accessible, though the computational requirements use to be high. Specific applications reviewed here include mechanistic studies of the Shilov and Wacker processes, speciation in Pd chemistry, hydrogen bonding to metal centers, and the dynamics of agostic interactions.
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Affiliation(s)
- Pietro Vidossich
- Departament de Química,
Edifici C.n., Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Catalonia, Spain
| | - Agustí Lledós
- Departament de Química,
Edifici C.n., Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Catalonia, Spain
| | - Gregori Ujaque
- Departament de Química,
Edifici C.n., Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Catalonia, Spain
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Realistic Simulation of Organometallic Reactivity in Solution by Means of First-Principles Molecular Dynamics. STRUCTURE AND BONDING 2015. [DOI: 10.1007/430_2015_183] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Codola Z, Lloret-Fillol J, Costas M. Aminopyridine Iron and Manganese Complexes as Molecular Catalysts for Challenging Oxidative Transformations. PROGRESS IN INORGANIC CHEMISTRY: VOLUME 59 2014. [DOI: 10.1002/9781118869994.ch07] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Zheng S, Pfaendtner J. Enhanced sampling of chemical and biochemical reactions with metadynamics. MOLECULAR SIMULATION 2014. [DOI: 10.1080/08927022.2014.923574] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Jovanović V, Miyazaki Y, Ebata T, Petković M. Vibrational Spectroscopy of Picolinamide and Water: From Dimers to Condensed Phase. J Phys Chem A 2013; 117:6474-82. [DOI: 10.1021/jp402033c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Vladimir Jovanović
- Institute of Theoretical and
Computational Chemistry, Heinrich-Heine-University Düsseldorf, Universitätsstraβe 1, 40225 Düsseldorf, Germany
- Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12, 11 158 Belgrade,
Serbia
| | - Yasunori Miyazaki
- Department of Chemistry, Graduate
School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Takayuki Ebata
- Department of Chemistry, Graduate
School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Milena Petković
- Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12, 11 158 Belgrade,
Serbia
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