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Majumder R, Sokolov AY. Consistent Second-Order Treatment of Spin-Orbit Coupling and Dynamic Correlation in Quasidegenerate N-Electron Valence Perturbation Theory. J Chem Theory Comput 2024; 20:4676-4688. [PMID: 38795071 DOI: 10.1021/acs.jctc.4c00458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2024]
Abstract
We present a formulation and implementation of second-order quasidegenerate N-electron valence perturbation theory (QDNEVPT2) that provides a balanced and accurate description of spin-orbit coupling and dynamic correlation effects in multiconfigurational electronic states. In our approach, the energies and wave functions of electronic states are computed by treating electron repulsion and spin-orbit coupling operators as equal perturbations to the nonrelativistic complete active-space wave functions, and their contributions are incorporated fully up to the second order. The spin-orbit effects are described using the Breit-Pauli (BP) or exact two-component Douglas-Kroll-Hess (DKH) Hamiltonians within spin-orbit mean-field approximation. The resulting second-order methods (BP2- and DKH2-QDNEVPT2) are capable of treating spin-orbit coupling effects in nearly degenerate electronic states by diagonalizing an effective Hamiltonian expanded in a compact non-relativistic basis. For a variety of atoms and small molecules across the entire periodic table, we demonstrate that DKH2-QDNEVPT2 is competitive in accuracy with variational two-component relativistic theories. BP2-QDNEVPT2 shows high accuracy for the second- and third-period elements, but its performance deteriorates for heavier atoms and molecules. We also consider the first-order spin-orbit QDNEVPT2 approximations (BP1- and DKH1-QDNEVPT2), among which DKH1-QDNEVPT2 is reliable but less accurate than DKH2-QDNEVPT2. Both DKH1- and DKH2-QDNEVPT2 hold promise as efficient and accurate electronic structure methods for treating electron correlation and spin-orbit coupling in a variety of applications.
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Affiliation(s)
- Rajat Majumder
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Alexander Yu Sokolov
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
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2
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Mishra S, Vilas-Varela M, Lieske LA, Ortiz R, Fatayer S, Rončević I, Albrecht F, Frederiksen T, Peña D, Gross L. Bistability between π-diradical open-shell and closed-shell states in indeno[1,2-a]fluorene. Nat Chem 2024; 16:755-761. [PMID: 38332330 PMCID: PMC11087267 DOI: 10.1038/s41557-023-01431-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 12/19/2023] [Indexed: 02/10/2024]
Abstract
Indenofluorenes are non-benzenoid conjugated hydrocarbons that have received great interest owing to their unusual electronic structure and potential applications in nonlinear optics and photovoltaics. Here we report the generation of unsubstituted indeno[1,2-a]fluorene on various surfaces by the cleavage of two C-H bonds in 7,12-dihydroindeno[1,2-a]fluorene through voltage pulses applied by the tip of a combined scanning tunnelling microscope and atomic force microscope. On bilayer NaCl on Au(111), indeno[1,2-a]fluorene is in the neutral charge state, but it exhibits charge bistability between neutral and anionic states on the lower-workfunction surfaces of bilayer NaCl on Ag(111) and Cu(111). In the neutral state, indeno[1,2-a]fluorene exhibits one of two ground states: an open-shell π-diradical state, predicted to be a triplet by density functional and multireference many-body perturbation theory calculations, or a closed-shell state with a para-quinodimethane moiety in the as-indacene core. We observe switching between open- and closed-shell states of a single molecule by changing its adsorption site on NaCl.
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Affiliation(s)
| | - Manuel Vilas-Varela
- Center for Research in Biological Chemistry and Molecular Materials (CiQUS) and Department of Organic Chemistry, University of Santiago de Compostela, Santiago de Compostela, Spain
| | | | - Ricardo Ortiz
- Donostia International Physics Center (DIPC), Donostia-San Sebastián, Spain
| | - Shadi Fatayer
- Applied Physics Program, Physical Science and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia
| | - Igor Rončević
- Department of Chemistry, University of Oxford, Oxford, UK
| | | | - Thomas Frederiksen
- Donostia International Physics Center (DIPC), Donostia-San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, Spain
| | - Diego Peña
- Center for Research in Biological Chemistry and Molecular Materials (CiQUS) and Department of Organic Chemistry, University of Santiago de Compostela, Santiago de Compostela, Spain.
| | - Leo Gross
- IBM Research Europe - Zurich, Rüschlikon, Switzerland.
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3
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Harriswangler C, Lucio-Martínez F, Rodríguez-Rodríguez A, Esteban-Gómez D, Platas-Iglesias C. Unravelling the 6sp ← 6s absorption spectra of Bi(III) complexes. Dalton Trans 2024; 53:2275-2285. [PMID: 38197124 DOI: 10.1039/d3dt03744d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2024]
Abstract
We report a spectroscopic and computational study that investigates the absorption spectra of Bi(III) complexes, which often show an absorption band in the UV region (∼270-350 nm) due to 6sp ← 6s transitions. We investigated the spectra of three simple complexes, [BiCl5]2-, [BiCl6]3- and [Bi(DMSO)8]3+, which show absorption maxima at 334, 326 and 279 nm due to 3P1 ← 1S0 transitions. Theoretical calculations based on quasi-degenerate N-electron valence perturbation theory to second order (QD-NEVPT2) provide an accurate description of the absorption spectra when employing CAS(2,9) wave functions. We next investigated the absorption spectra of the [Bi(NOTA)] complex (H3NOTA = 1,4,7-triazacyclononane-1,4,7-triacetic acid), which forms ternary complexes [Bi(NOTA)X]- (X = Cl, Br or I) in the presence of excess halide in aqueous solutions. Halide binding has an important impact on the position of the 3P1 ← 1S0 transition, which shifts progressively to longer wavelengths from 282 nm ([Bi(NOTA)]) to 298 nm (X = Cl), 305 nm (X = Br) and 325 nm (X = I). Subsequent QD-NEVPT2 calculations indicate that this effect is related to the progressive stabilization of the spin-orbit free states associated with the 6s16p1 configuration on increasing the covalent character of the metal-ligand(s) bonds, rather than with significant differences in spin-orbit coupling (SOC). These studies provide valuable insight into the coordination chemistry of Bi(III), an ion with increasing interest in targeted alpha therapy due to the possible application of bismuth isotopes bismuth-212 (212Bi, t1/2 = 60.6 min) and bismuth-213 (213Bi, t1/2 = 45.6 min).
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Affiliation(s)
- Charlene Harriswangler
- Universidade da Coruña, Centro de Interdisciplinar de Química e Bioloxía (CICA) and Departamento de Química, Facultade de Ciencias, 15071, A Coruña, Galicia, Spain.
| | - Fátima Lucio-Martínez
- Universidade da Coruña, Centro de Interdisciplinar de Química e Bioloxía (CICA) and Departamento de Química, Facultade de Ciencias, 15071, A Coruña, Galicia, Spain.
| | - Aurora Rodríguez-Rodríguez
- Universidade da Coruña, Centro de Interdisciplinar de Química e Bioloxía (CICA) and Departamento de Química, Facultade de Ciencias, 15071, A Coruña, Galicia, Spain.
| | - David Esteban-Gómez
- Universidade da Coruña, Centro de Interdisciplinar de Química e Bioloxía (CICA) and Departamento de Química, Facultade de Ciencias, 15071, A Coruña, Galicia, Spain.
| | - Carlos Platas-Iglesias
- Universidade da Coruña, Centro de Interdisciplinar de Química e Bioloxía (CICA) and Departamento de Química, Facultade de Ciencias, 15071, A Coruña, Galicia, Spain.
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4
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Errulat D, Harriman KLM, Gálico DA, Kitos AA, Mansikkamäki A, Murugesu M. A trivalent 4f complex with two bis-silylamide ligands displaying slow magnetic relaxation. Nat Chem 2023:10.1038/s41557-023-01208-y. [PMID: 37231297 DOI: 10.1038/s41557-023-01208-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 04/17/2023] [Indexed: 05/27/2023]
Abstract
The best-performing single-molecule magnets (SMMs) have historically relied on pseudoaxial ligands delocalized across several coordinated atoms. This coordination environment has been found to elicit strong magnetic anisotropy, but lanthanide-based SMMs with low coordination numbers have remained synthetically elusive species. Here we report a cationic 4f complex bearing only two bis-silylamide ligands, Yb(III)[{N(SiMePh2)2}2][Al{OC(CF3)3}4], which exhibits slow relaxation of its magnetization. The combination of the bulky silylamide ligands and weakly coordinating [Al{OC(CF3)3}4]- anion provides a sterically hindered environment that suitably stabilizes the pseudotrigonal geometry necessary to elicit strong ground-state magnetic anisotropy. The resolution of the mJ states by luminescence spectroscopy is supported by ab initio calculations, which show a large ground-state splitting of approximately 1,850 cm-1. These results provide a facile route to access a bis-silylamido Yb(III) complex, and further underline the desirability of axially coordinated ligands with well-localized charges for high-performing SMMs.
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Affiliation(s)
- Dylan Errulat
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - Katie L M Harriman
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - Diogo A Gálico
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - Alexandros A Kitos
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | | | - Muralee Murugesu
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, Canada.
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5
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Cagan DA, Bím D, Silva B, Kazmierczak NP, McNicholas BJ, Hadt RG. Elucidating the Mechanism of Excited-State Bond Homolysis in Nickel-Bipyridine Photoredox Catalysts. J Am Chem Soc 2022; 144:6516-6531. [PMID: 35353530 PMCID: PMC9979631 DOI: 10.1021/jacs.2c01356] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Ni 2,2'-bipyridine (bpy) complexes are commonly employed photoredox catalysts of bond-forming reactions in organic chemistry. However, the mechanisms by which they operate are still under investigation. One potential mode of catalysis is via entry into Ni(I)/Ni(III) cycles, which can be made possible by light-induced, excited-state Ni(II)-C bond homolysis. Here, we report experimental and computational analyses of a library of Ni(II)-bpy aryl halide complexes, Ni(Rbpy)(R'Ph)Cl (R = MeO, t-Bu, H, MeOOC; R' = CH3, H, OMe, F, CF3), to illuminate the mechanism of excited-state bond homolysis. At given excitation wavelengths, photochemical homolysis rate constants span 2 orders of magnitude across these structures and correlate linearly with Hammett parameters of both bpy and aryl ligands, reflecting structural control over key metal-to-ligand charge-transfer (MLCT) and ligand-to-metal charge-transfer (LMCT) excited-state potential energy surfaces (PESs). Temperature- and wavelength-dependent investigations reveal moderate excited-state barriers (ΔH‡ ∼ 4 kcal mol-1) and a minimum energy excitation threshold (∼55 kcal mol-1, 525 nm), respectively. Correlations to electronic structure calculations further support a mechanism in which repulsive triplet excited-state PESs featuring a critical aryl-to-Ni LMCT lead to bond rupture. Structural control over excited-state PESs provides a rational approach to utilize photonic energy and leverage excited-state bond homolysis processes in synthetic chemistry.
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Affiliation(s)
- David A. Cagan
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - Daniel Bím
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - Breno Silva
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States,Department of Chemistry and Biochemistry, Suffolk University, Boston, Massachusetts 02108, United States
| | - Nathanael P. Kazmierczak
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - Brendon J. McNicholas
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States
| | - Ryan G. Hadt
- Division of Chemistry and Chemical Engineering, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, United States,Corresponding Author:
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6
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Neese F. Software update: The
ORCA
program system—Version 5.0. WIRES COMPUTATIONAL MOLECULAR SCIENCE 2022. [DOI: 10.1002/wcms.1606] [Citation(s) in RCA: 49] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Frank Neese
- Max Planck Institut für Kohlenforschung Mülheim an der Ruhr Germany
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Atanasov M, Andreici Eftimie EL, Avram NM, Brik MG, Neese F. First-Principles Study of Optical Absorption Energies, Ligand Field and Spin-Hamiltonian Parameters of Cr 3+ Ions in Emeralds. Inorg Chem 2021; 61:178-192. [PMID: 34930002 DOI: 10.1021/acs.inorgchem.1c02650] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Herein, we study the electronic structure, energies, and vibronic structure of optical d-d transitions of Cr3+ ions doped in beryl (Be3Si6Al2O18:Cr3+, emerald). A computational protocol is developed that combines periodic density functional theory (for modeling of the bulk crystalline lattice of emerald) and the multireference configuration interaction complete active space self-consistent field method supplemented with n-electron valence second-order perturbation theory (for the calculation of the energy levels, wave functions, and spin-Hamiltonian and ligand-field parameters of the trigonal Cr3+ centers in the [CrO6]9- clusters embedded in an extended point charge field). Ligand-field parameters were extracted from mapping the effective ligand-field Hamiltonian onto the full many-particle Hamiltonian from one side and from a direct fit to energies of computed d-d transitions on the other side. These have been analyzed using ab initio ligand-field theory. The quality of the theoretical predictions is critically assessed through a detailed comparison with the available experimental data.
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Affiliation(s)
- Mihail Atanasov
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr D-45470, Germany.,Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
| | | | - Nicolae M Avram
- Department of Physics, West University of Timisoara, Bd.V. Parvan No. 4, Timisoara 300223, Romania.,Academy of Romanian Scientists, Ilfov 3, Bucharest 050044, Romania
| | - Mikhail G Brik
- Institute of Physics, University of Tartu, W. Ostwald Str. 1, Tartu 50411, Estonia.,CQUPT-BUL Innovation Institute & College of Sciences, Chongqing University of Posts and Telecommunications, Chongqing 400065, People's Republic of China.,Faculty of Science and Technology, Jan Długosz University, Armii Krajowej 13/15, Częstochowa PL-42200, Poland.,Academy of Romanian Scientists, Ilfov 3, Bucharest 050044, Romania
| | - Frank Neese
- Department of Molecular Theory and Spectroscopy, Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr D-45470, Germany
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8
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Neese F, Wennmohs F, Becker U, Riplinger C. The ORCA quantum chemistry program package. J Chem Phys 2020; 152:224108. [DOI: 10.1063/5.0004608] [Citation(s) in RCA: 697] [Impact Index Per Article: 174.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Frank Neese
- Max Planck Institut für Kohlenforschung, Kaiser-Wilhelm Platz 1, D-45470 Mülheim an der Ruhr, Germany
- FAccTs GmbH, Rolandstr. 67, 50677 Köln, Germany
| | - Frank Wennmohs
- Max Planck Institut für Kohlenforschung, Kaiser-Wilhelm Platz 1, D-45470 Mülheim an der Ruhr, Germany
| | - Ute Becker
- Max Planck Institut für Kohlenforschung, Kaiser-Wilhelm Platz 1, D-45470 Mülheim an der Ruhr, Germany
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9
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Lang L, Atanasov M, Neese F. Improvement of Ab Initio Ligand Field Theory by Means of Multistate Perturbation Theory. J Phys Chem A 2020; 124:1025-1037. [PMID: 31977214 PMCID: PMC7307914 DOI: 10.1021/acs.jpca.9b11227] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
![]()
Over
the last few years, ab initio ligand field theory (AILFT)
has evolved into an important tool for the extraction of ligand field
models from ab initio calculations. The inclusion of dynamic correlation
on top of complete active space self-consistent field (CASSCF) reference
functions, which is important for accurate results, was so far realized
at the level of second-order N-electron valence state perturbation
theory (NEVPT2). In this work, we introduce two alternative methods
for the inclusion of dynamic correlation into AILFT calculations,
the second-order dynamic correlation dressed complete active space
method (DCD-CAS(2)) and the Hermitian quasi-degenerate NEVPT2 (HQD-NEVPT2).
These methods belong to the class of multistate perturbation theory
approaches, which allow for the mixing of CASSCF states under the
effect of dynamic correlation (state-mixing). The two new versions
of AILFT were tested for a diverse set of transition-metal complexes.
It was found that the multistate methods have, compared to NEVPT2,
an AILFT fit with smaller root mean square deviations (rmsds) between
ab initio and AILFT energies. A comparison of AILFT excitation energies
with the experiment shows that for some systems, the agreement gets
better at the multistate level because of the smaller rmsds. However,
for some systems, the agreement gets worse, which could be attributed
to a cancellation of errors at the NEVPT2 level that is partly removed
at the multistate level. An investigation of trends in the extracted
ligand field parameters shows that at the multistate level, the ligand
field splitting Δ gets larger, whereas the Racah parameters B and C get smaller and larger, respectively.
An investigation of the reasons for the observed improvement for octahedral
CrIII halide complexes shows that the possibility of state-mixing
relaxes constraints that are present at the NEVPT2 level and that
keep Δ and B from following their individual
preferences.
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Affiliation(s)
- Lucas Lang
- Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1 , 45470 Mülheim an der Ruhr , Germany
| | - Mihail Atanasov
- Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1 , 45470 Mülheim an der Ruhr , Germany.,Institute of General and Inorganic Chemistry , Bulgarian Academy of Sciences , Akad. Georgi Bontchev Street 11 , 1113 Sofia , Bulgaria
| | - Frank Neese
- Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1 , 45470 Mülheim an der Ruhr , Germany
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