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Han R, Luber S, Li Manni G. Magnetic Interactions in a [Co(II) 3Er(III)(OR) 4] Model Cubane through Forefront Multiconfigurational Methods. J Chem Theory Comput 2023; 19:2811-2826. [PMID: 37126736 DOI: 10.1021/acs.jctc.2c01318] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Strong electron correlation effects are one of the major challenges in modern quantum chemistry. Polynuclear transition metal clusters are peculiar examples of systems featuring such forms of electron correlation. Multireference strategies, often based on but not limited to the concept of complete active space, are adopted to accurately account for strong electron correlation and to resolve their complex electronic structures. However, transition metal clusters already containing four magnetic centers with multiple unpaired electrons make conventional active space based strategies prohibitively expensive, due to their unfavorable scaling with the size of the active space. In this work, forefront techniques, such as density matrix renormalization group (DMRG), full configuration interaction quantum Monte Carlo (FCIQMC), and multiconfiguration pair-density functional theory (MCPDFT), are employed to overcome the computational limitation of conventional multireference approaches and to accurately investigate the magnetic interactions taking place in a [Co(II)3Er(III)(OR)4] (chemical formula [Co(II)3Er(III)(hmp)4(μ2-OAc)2(OH)3(H2O)], hmp = 2-(hydroxymethyl)-pyridine) model cubane water oxidation catalyst. Complete active spaces with up to 56 electrons in 56 orbitals have been constructed for the seven energetically lowest different spin states. Relative energies, local spin, and spin-spin correlation values are reported and provide crucial insights on the spin interactions for this model system, pivotal in the rationalization of the catalytic activity of this system in the water-splitting reaction. A ferromagnetic ground state is found with a very small, ∼50 cm-1, highest-to-lowest spin gap. Moreover, for the energetically lowest states, S = 3-6, the three Co(II) sites exhibit parallel aligned spins, and for the lower states, S = 0-2, two Co(II) sites retain strong parallel spin alignment.
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Affiliation(s)
- Ruocheng Han
- Department of Chemistry A, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Sandra Luber
- Department of Chemistry A, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Giovanni Li Manni
- Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
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2
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Larsson HR, Zhai H, Umrigar CJ, Chan GKL. The Chromium Dimer: Closing a Chapter of Quantum Chemistry. J Am Chem Soc 2022; 144:15932-15937. [PMID: 36001866 PMCID: PMC9460780 DOI: 10.1021/jacs.2c06357] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The complex electronic structure and unusual potential energy curve of the chromium dimer have fascinated scientists for decades, with agreement between theory and experiment so far elusive. Here, we present a new ab initio simulation of the potential energy curve and vibrational spectrum that significantly improves on all earlier estimates. Our data support a shift in earlier experimental assignments of a cluster of vibrational frequencies by one quantum number. The new vibrational assignment yields an experimentally derived potential energy curve in quantitative agreement with theory across all bond lengths and across all measured frequencies. By solving this long-standing problem, our results raise the possibility of quantitative quantum chemical modeling of transition metal clusters with spectroscopic accuracy.
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Affiliation(s)
- Henrik R Larsson
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.,Department of Chemistry and Biochemistry, University of California Merced, Merced, California 95343, United States
| | - Huanchen Zhai
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - C J Umrigar
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, United States
| | - Garnet Kin-Lic Chan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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3
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Csizi KS, Eckert L, Brunken C, Hofstetter TB, Reiher M. The Apparently Unreactive Substrate Facilitates the Electron Transfer for Dioxygen Activation in Rieske Dioxygenases. Chemistry 2022; 28:e202103937. [PMID: 35072969 PMCID: PMC9306888 DOI: 10.1002/chem.202103937] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Indexed: 12/29/2022]
Abstract
Rieske dioxygenases belong to the non‐heme iron family of oxygenases and catalyze important cis‐dihydroxylation as well as O‐/N‐dealkylation and oxidative cyclization reactions for a wide range of substrates. The lack of substrate coordination at the non‐heme ferrous iron center, however, makes it particularly challenging to delineate the role of the substrate for productive O2
activation. Here, we studied the role of the substrate in the key elementary reaction leading to O2
activation from a theoretical perspective by systematically considering (i) the 6‐coordinate to 5‐coordinate conversion of the non‐heme FeII upon abstraction of a water ligand, (ii) binding of O2
, and (iii) transfer of an electron from the Rieske cluster. We systematically evaluated the spin‐state‐dependent reaction energies and structural effects at the active site for all combinations of the three elementary processes in the presence and absence of substrate using naphthalene dioxygenase as a prototypical Rieske dioxygenase. We find that reaction energies for the generation of a coordination vacancy at the non‐heme FeII
center through thermoneutral H2O reorientation and exothermic O2
binding prior to Rieske cluster oxidation are largely insensitive to the presence of naphthalene and do not lead to formation of any of the known reactive Fe‐oxygen species. By contrast, the role of the substrate becomes evident after Rieske cluster oxidation and exclusively for the 6‐coordinate non‐heme FeII
sites in that the additional electron is found at the substrate instead of at the iron and oxygen atoms. Our results imply an allosteric control of the substrate on Rieske dioxygenase reactivity to happen prior to changes at the non‐heme FeII
in agreement with a strategy that avoids unproductive O2
activation.
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Affiliation(s)
- Katja-Sophia Csizi
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600, Dübendorf, Switzerland.,ETH Zürich, Laboratory for Physical Chemistry, Vladimir-Prelog-Weg 2, 8093, Zürich, Switzerland
| | - Lina Eckert
- ETH Zürich, Laboratory for Physical Chemistry, Vladimir-Prelog-Weg 2, 8093, Zürich, Switzerland
| | - Christoph Brunken
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600, Dübendorf, Switzerland.,ETH Zürich, Laboratory for Physical Chemistry, Vladimir-Prelog-Weg 2, 8093, Zürich, Switzerland
| | - Thomas B Hofstetter
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600, Dübendorf, Switzerland
| | - Markus Reiher
- ETH Zürich, Laboratory for Physical Chemistry, Vladimir-Prelog-Weg 2, 8093, Zürich, Switzerland
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4
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Drosou M, Mitsopoulou CA, Pantazis DA. Spin-state energetics of manganese spin crossover complexes: Comparison of single-reference and multi-reference ab initio approaches. Polyhedron 2021. [DOI: 10.1016/j.poly.2021.115399] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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5
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Singh G, Gamboa S, Orio M, Pantazis DA, Roemelt M. Magnetic exchange coupling in Cu dimers studied with modern multireference methods and broken-symmetry coupled cluster theory. Theor Chem Acc 2021. [DOI: 10.1007/s00214-021-02830-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
AbstractSpin-state energetics of exchange-coupled copper complexes pose a persistent challenge for applied quantum chemistry. Here, we provide a comprehensive comparison of all available theoretical approaches to the problem of exchange coupling in two antiferromagnetically coupled bis-μ-hydroxo Cu(II) dimers. The evaluated methods include multireference methods based on the density matrix renormalization group (DMRG), multireference methods that incorporate dynamic electron correlation either perturbatively, such as the N-electron valence state perturbation theory, or variationally, such as the difference-dedicated configuration interaction. In addition, we contrast the multireference results with those obtained using broken-symmetry approaches that utilize either density functional theory or, as demonstrated here for the first time in such systems, a local implementation of coupled cluster theory. The results show that the spin-state energetics of these copper dimers are dominated by dynamic electron correlation and represent an impossible challenge for multireference methods that rely on brute-force expansion of the active space to recover correlation energy. Therefore, DMRG-based methods even at the limit of their applicability cannot describe quantitatively the antiferromagnetic exchange coupling in these dimers, in contrast to dinuclear complexes of earlier transition metal ions. The convergence of the broken-symmetry coupled cluster approach is studied and shown to be a limiting factor for the practical application of the method. The advantages and disadvantages of all approaches are discussed, and recommendations are made for future developments.
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6
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Li Manni G. Modeling magnetic interactions in high-valent trinuclear [Mn 3(IV)O 4] 4+ complexes through highly compressed multi-configurational wave functions. Phys Chem Chem Phys 2021; 23:19766-19780. [PMID: 34525156 DOI: 10.1039/d1cp03259c] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work we apply a quantum chemical framework, recently designed in our laboratories, to rationalize the low-energy electronic spectrum and the magnetic properties of an homo-valent trinuclear [Mn3(IV)O4]4+ model of the oxygen-evolving center in photosystem II. The method is based on chemically motivated molecular orbital unitary transformations, and the optimization of spin-adapted many-body wave functions, both for ground- and excited-states, in the transformed MO basis. In this basis, the configuration interaction Hamiltonian matrix of exchange-coupled multi-center clusters is extremely sparse and characterized by a unique block diagonal structure. This property leads to highly compressed wave functions (oligo- or single-reference) and crucially enables state-specific optimizations. This work is the first showing that compression and selective targeting of ground- and excited-states wave functions is possible for systems with three magnetic centers that are not exactly half-filled, and that potentially exhibit frustrated spin interactions. The reduced multi-reference character of the wave function greatly simplifies the interpretation of the ground- and excited-state electronic structures, and provides a route for the direct rationalization of magnetic interactions in these compounds, often considered a challenge in polynuclear transition-metal chemistry. In this study, strong electron correlation effects have explicitly been described by conventional and stochastic multiconfigurational methodologies, while dynamic correlation effects have been accounted for by multiconfigurational second order perturbation theory, CASPT2. Ab initio results for the [Mn3(IV)O4]4+ system have been mapped to a three-site Heisenberg model with two magnetic coupling constants. The magnetic coupling constants and the temperature dependence of the effective magnetic moment predicted by the ab initio calculations are in good agreement with the available experimental data, and confirm the antiferromagnetic interaction among the three magnetic centers, while providing a simple and rigorous description of the noncollinearity of the local spins, that characterize most of the low-energy states for this system.
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Affiliation(s)
- Giovanni Li Manni
- Department of Electronic Structure Theory, Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany.
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7
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Khedkar A, Roemelt M. Modern multireference methods and their application in transition metal chemistry. Phys Chem Chem Phys 2021; 23:17097-17112. [PMID: 34355719 DOI: 10.1039/d1cp02640b] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Transition metal chemistry is a challenging playground for quantum chemical methods owing to the simultaneous presence of static and dynamic electron correlation effects in many systems. Wavefunction based multireference (MR) methods constitute a physically sound and systematically improvable Ansatz to deal with this complexity but suffer from some conceptual difficulties and high computational costs. The latter problem partially arises from the unfavorable scaling of the Full Configuration Interaction (Full-CI) problem which in the majority of MR methods is solved for a subset of the molecular orbital space, the so-called active space. In the last years multiple methods such as modern variants of selected CI, Full-CI Quantum Monte Carlo (FCIQMC) and the density matrix renormalization group (DMRG) have been developed that solve the Full-CI problem approximately for a fraction of the computational cost required by conventional techniques thereby significantly extending the range of applicability of modern MR methods. This perspective review outlines recent advancements in the field of MR electronic structure methods together with the resulting chances and challenges for theoretical studies in the field of transition metal chemistry. In light of its emerging importance a special focus is put on the selection of adequate active spaces and the concomitant development of numerous selection aides in recent years.
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Affiliation(s)
- Abhishek Khedkar
- Lehrstuhl für theoretische Chemie, Ruhr-Universität Bochum, D-44780 Bochum, Germany.
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8
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Corry TA, Rummel F, O'Malley PJ. Bonding and Magnetic Exchange Pathways in Nature's Water-Oxidizing Complex. J Phys Chem B 2021; 125:7147-7154. [PMID: 34180671 DOI: 10.1021/acs.jpcb.1c03864] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The nature of the bonding and magnetic exchange pathways of the water-oxidizing complex of photosystem 2 is explored using broken symmetry density functional theory. The electronic structure and superexchange pathways are illustrated and analyzed using corresponding orbitals and intrinsic bond orbitals. These demonstrate a dominating influence on the bonding and magnetic interactions by both the geometrical structure of the Mn4CaO5 core complex and the ionic interactions of the oxo bridges with the neighboring Ca2+ ion. The demonstrated ionic nature of the Ca2+ bonds is proposed to contribute to the stabilization of the oxygen atoms participating in O-O bond formation.
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Affiliation(s)
- Thomas A Corry
- Department of Chemistry, School of Natural Sciences, The University of Manchester, Manchester M13 9PL, U.K
| | - Felix Rummel
- Department of Chemistry, School of Natural Sciences, The University of Manchester, Manchester M13 9PL, U.K
| | - Patrick J O'Malley
- Department of Chemistry, School of Natural Sciences, The University of Manchester, Manchester M13 9PL, U.K
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Li Manni G, Dobrautz W, Bogdanov NA, Guther K, Alavi A. Resolution of Low-Energy States in Spin-Exchange Transition-Metal Clusters: Case Study of Singlet States in [Fe(III) 4S 4] Cubanes. J Phys Chem A 2021; 125:4727-4740. [PMID: 34048648 PMCID: PMC8201447 DOI: 10.1021/acs.jpca.1c00397] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
![]()
Polynuclear transition-metal
(PNTM) clusters owe their catalytic
activity to numerous energetically low-lying spin states and stable
oxidation states. The characterization of their electronic structure
represents one of the greatest challenges of modern chemistry. We
propose a theoretical framework that enables the resolution of targeted
electronic states with ease and apply it to two [Fe(III)4S4] cubanes. Through direct access to their many-body
wave functions, we identify important correlation mechanisms and their
interplay with the geometrical distortions observed in these clusters,
which are core properties in understanding their catalytic activity.
The simulated magnetic coupling constants predicted by our strategy
allow us to make qualitative connections between spin interactions
and geometrical distortions, demonstrating its predictive power. Moreover,
despite its simplicity, the strategy provides magnetic coupling constants
in good agreement with the available experimental ones. The complexes
are intrinsically frustrated anti-ferromagnets, and the obtained spin
structures together with the geometrical distortions represent two
possible ways to release spin frustration (spin-driven Jahn–Teller
distortion). Our paradigm provides a simple, yet rigorous, route to
uncover the electronic structure of PNTM clusters and may be applied
to a wide variety of such clusters.
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Affiliation(s)
- Giovanni Li Manni
- Department of Electronic Structure Theory, Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Werner Dobrautz
- Department of Electronic Structure Theory, Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Nikolay A Bogdanov
- Department of Electronic Structure Theory, Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Kai Guther
- Department of Electronic Structure Theory, Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany
| | - Ali Alavi
- Department of Electronic Structure Theory, Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569 Stuttgart, Germany.,Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
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10
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Chalupský J, Srnec M. Beyond the Classical Contributions to Exchange Coupling in Binuclear Transition Metal Complexes. J Phys Chem A 2021; 125:2276-2283. [PMID: 33724818 DOI: 10.1021/acs.jpca.0c11237] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Complexes with two or more magnetically coupled metal ions have attracted considerable attention as catalysts of many vital processes, single-molecule magnets, or spin-crossover compounds. Elucidation of their electronic structures is essential for understanding their catalytic and magnetic properties. Here, we provide an unprecedented insight into exchange-coupling mechanisms between the magnetic centers in six prototypical bis-μ-oxo bimetallic M2O2 complexes, including two biologically relevant models of non-heme iron enzymes. Employing multiconfigurational/multireference methods and related orbital entanglement analysis, we revealed the essential and counterintuitive role of predominantly unoccupied valence metal d orbitals in their strong antiferromagnetic coupling. We found that the participation of these orbitals is twofold. First, they enhance the superexchange between the singly occupied d orbitals. Second, they become substantially occupied and thus directly magnetically active, which we perceive as a new mechanism of the exchange interaction between the magnetic transition metal centers.
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Affiliation(s)
- Jakub Chalupský
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo náměstí 2, Prague 6 16610, Czech Republic
| | - Martin Srnec
- J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, Prague 8 18223, Czech Republic
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Chalupský J, Srnec M, Yanai T. Interpretation of Exchange Interaction through Orbital Entanglement. J Phys Chem Lett 2021; 12:1268-1274. [PMID: 33497240 DOI: 10.1021/acs.jpclett.0c03652] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Recently, the analysis of single-orbital entropy and mutual information has been introduced as a tool for the investigation of contributions to the exchange (J) coupling between open-shell metal ions [Stein et al. J. Phys. Chem. Lett. 2019, 10, 6762-6770]. Here, we show that this analysis may lead to an incorrect interpretation of the J-coupling mechanism. Instead, we propose an orbital-entanglement analysis that is based on the two-electron density and that provides a coherent picture of the contributing exchange pathways, which seems fully consistent with the available J values. For this purpose, we used a prototypical bis-μ-oxo binuclear manganese complex ([Mn2O2(NH3)8]4+) and demonstrated that its antiferromagnetism (J < 0), calculated by using the active space composed of all valence pO and dMn orbitals, correlates well with the largest elements in the differential low-spin vs high-spin entanglement map. These elements correspond to interactions between the pairs of dMn orbitals mediated by the oxo-bridging out-of-plane p orbitals, representing the π superexchange pathway. We also show that the reduction of active space to manifold of the singly occupied magnetic orbitals does not lead to discrepancy between the calculated J values and entanglement maps. This contrasts to analysis of mutual information, which suggests the "direct" dMn-dMn interactions to play a dominant role for the J coupling, irrespective of the size of active space as well as of the antiferromagnetism expected. The failure is attributed to the large contribution of spin entanglement contained in the mutual information of the low-spin state, which may be regarded as the origin of the different complexity of its wave function and electron density.
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Affiliation(s)
- Jakub Chalupský
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo náměstí 2, 166 10 Prague 6, Czech Republic
| | - Martin Srnec
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejškova 3, 182 23 Prague 8, Czech Republic
| | - Takeshi Yanai
- Department of Chemistry, Graduate School of Science, Nagoya University, Furocho, Chikusa Ward, Nagoya, Aichi 464-8601, Japan
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furocho, Chikusa Ward, Nagoya, Aichi 464-8601, Japan
- Japan Science and Technology Agency, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
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Orio M, Pantazis DA. Successes, challenges, and opportunities for quantum chemistry in understanding metalloenzymes for solar fuels research. Chem Commun (Camb) 2021; 57:3952-3974. [DOI: 10.1039/d1cc00705j] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Overview of the rich and diverse contributions of quantum chemistry to understanding the structure and function of the biological archetypes for solar fuel research, photosystem II and hydrogenases.
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Affiliation(s)
- Maylis Orio
- Aix-Marseille Université
- CNRS
- iSm2
- Marseille
- France
| | - Dimitrios A. Pantazis
- Max-Planck-Institut für Kohlenforschung
- Kaiser-Wilhelm-Platz 1
- 45470 Mülheim an der Ruhr
- Germany
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13
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Baiardi A, Reiher M. The density matrix renormalization group in chemistry and molecular physics: Recent developments and new challenges. J Chem Phys 2020; 152:040903. [DOI: 10.1063/1.5129672] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Affiliation(s)
- Alberto Baiardi
- ETH Zürich, Laboratorium für Physikalische Chemie, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
| | - Markus Reiher
- ETH Zürich, Laboratorium für Physikalische Chemie, Vladimir-Prelog-Weg 2, 8093 Zürich, Switzerland
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