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Li W, Filatov M, Zou W. Calculation of electric field gradients with the exact two-component (X2C) quasi-relativistic method and its local approximations. Phys Chem Chem Phys 2024; 26:18333-18342. [PMID: 38912554 DOI: 10.1039/d4cp01567c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/25/2024]
Abstract
When calculating electric field gradients (EFGs), relativistic and electron correlation effects are crucial for obtaining accurate results, and the commonly used density functional methods produce unsatisfactory results, especially for heavy elements and/or strongly correlated systems. In this work, a stand-alone program is presented, which enables calculation of EFGs from the molecular orbitals supplied by an external high accuracy quantum chemical calculation and includes relativistic effects through the exact two-component (X2C) formalism and efficient local approximations to it. Application to BiN and BiP molecules shows that a high precision can be achieved in the calculation of nuclear quadrupole coupling constants of 209Bi by combining advanced ab initio methods with the X2C approach. For seventeen iron compounds, the Mössbauer nuclear quadrupole splittings (NQS) of 57Fe calculated using a double-hybrid functional method are in very good agreement with the experimental values. It is shown that, for strongly correlated molecules, the double-hybrid functionals are much more accurate than the commonly used hybrid functionals. The computer program developed in this study furnishes a useful utility for obtaining EFGs and related nuclear properties with high accuracy.
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Affiliation(s)
- Wenxin Li
- Institute of Modern Physics, Northwest University, and Shaanxi Key Laboratory for Theoretical Physics Frontiers, Xi'an, Shaanxi 710127, P. R. China.
| | - Michael Filatov
- Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS), Ulsan, 44919, Republic of Korea.
| | - Wenli Zou
- Institute of Modern Physics, Northwest University, and Shaanxi Key Laboratory for Theoretical Physics Frontiers, Xi'an, Shaanxi 710127, P. R. China.
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2
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Pissas M, Ferentinos E, Kyritsis P, Sanakis Y. Field-Induced Slow Magnetization Relaxation of a Tetrahedral S=2 Fe IIS 4-Containing Complex. Chempluschem 2024:e202400109. [PMID: 38727531 DOI: 10.1002/cplu.202400109] [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: 02/06/2024] [Revised: 05/08/2024] [Indexed: 06/09/2024]
Abstract
In the work described herein, the spin relaxation properties of the mononuclear tetrahedral S=2 [Fe{(SPiPr2)2N}2] complex (1) were studied by employing static and dynamic magnetic measurements at liquid helium temperatures. In the absence of an external direct current (DC) magnetic field, 1 exhibits fast magnetization relaxation. However, in the presence of external magnetic fields of a few kOe, slow relaxation is induced as monitored by alternating current (AC) magnetic susceptibility measurements up to 10 kHz, in the temperature range 2-5 K. Analysis of the temperature dependence of the corresponding relaxation time reveals contributions by Quantum Tunnelling of Magnetization, and the Direct and Orbach processes in the magnetization relaxation mechanism of 1. The energy barrier, Ueff, of the Orbach process, as determined by this analysis, is compared with that related to the zero-field splitting parameters of 1 which were previously determined by high- frequency and -field electron paramagnetic resonance and Mössbauer spectroscopies.
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Affiliation(s)
- Michael Pissas
- Institute of Nanoscience and Nanotechnology, NCSR Demokritos, 15341, Ag. Paraskevi, Attiki, Greece
| | - Eleftherios Ferentinos
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, 15571, Athens, Greece
| | - Panayotis Kyritsis
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, 15571, Athens, Greece
| | - Yiannis Sanakis
- Institute of Nanoscience and Nanotechnology, NCSR Demokritos, 15341, Ag. Paraskevi, Attiki, Greece
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3
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Toubiana LA, Valaydon-Pillay A, Elinburg JK, Bacon JW, Ozarowski A, Doerrer LH, Stoian SA. Spectroscopic and Theoretical Investigation of High-Spin Square-Planar and Trigonal Fe(II) Complexes Supported by Fluorinated Alkoxides. Inorg Chem 2024; 63:2370-2387. [PMID: 38259134 DOI: 10.1021/acs.inorgchem.3c03236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
The electronic structures and spectroscopic behavior of three high-spin FeII complexes of fluorinated alkoxides were studied: square-planar {K(DME)2}2[Fe(pinF)2] (S) and quasi square-planar {K(C222)}2[Fe(pinF)2] (S') and trigonal-planar {K(18C6)}[Fe(OC4F9)3] (T) where pinF = perfluoropinacolate and OC4F9 = tris-perfluoro-t-butoxide. The zero-field splitting (ZFS) and hyperfine structure parameters of the S = 2 ground states were determined using field-dependent 57Fe Mössbauer and high-field and -frequency electron paramagnetic resonance (HFEPR) spectroscopies. The spin Hamiltonian parameters were analyzed with crystal field theory and corroborated by density functional theory (DFT) and ab initio complete active space self-consistent field (CASSCF) calculations. Whereas the ZFS tensor of S has a small rhombicity, E/D = 0.082, and a positive D = 15.17 cm-1, T exhibits a negative D = -9.16 cm-1 and a large rhombicity, E/D = 0.246. Computational investigation of the structural factors suggests that the ground-state electronic configuration and geometry of T's Fe site are determined by the interaction of [Fe(OC4F9)3]- with {K(18C6)}+. In contrast, two distinct countercations of S/S' have a negligible influence on their [Fe(pinF)2]2- moieties. Instead, the distortions in S' are likely induced by the chelate ring conformation change from δλ, observed for S, to the δδ conformation, determined for S'.
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Affiliation(s)
- Léa A Toubiana
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Adam Valaydon-Pillay
- Department of Chemistry, University of Idaho, Moscow, Idaho 83844, United States
| | - Jessica K Elinburg
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Jeffrey W Bacon
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Andrew Ozarowski
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Linda H Doerrer
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Sebastian A Stoian
- Department of Chemistry, University of Idaho, Moscow, Idaho 83844, United States
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Genoux A, Pauly M, Rooney CL, Choi C, Shang B, McGuigan S, Fataftah MS, Kayser Y, Suhr SCB, DeBeer S, Wang H, Maggard PA, Holland PL. Well-Defined Iron Sites in Crystalline Carbon Nitride. J Am Chem Soc 2023; 145:20739-20744. [PMID: 37703184 DOI: 10.1021/jacs.3c05417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/15/2023]
Abstract
Carbon nitride materials can be hosts for transition metal sites, but Mössbauer studies on iron complexes in carbon nitrides have always shown a mixture of environments and oxidation states. Here we describe the synthesis and characterization of a crystalline carbon nitride with stoichiometric iron sites that all have the same environment. The material (formula C6N9H2Fe0.4Li1.2Cl, abbreviated PTI/FeCl2) is derived from reacting poly(triazine imide)·LiCl (PTI/LiCl) with a low-melting FeCl2/KCl flux, followed by anaerobic rinsing with methanol. X-ray diffraction, X-ray absorption and Mössbauer spectroscopies, and SQUID magnetometry indicate that there are tetrahedral high-spin iron(II) sites throughout the material, all having the same geometry. The material is active for electrocatalytic nitrate reduction to ammonia, with a production rate of ca. 0.1 mmol cm-2 h-1 and Faradaic efficiency of ca. 80% at -0.80 V vs RHE.
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Affiliation(s)
- Alexandre Genoux
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Magnus Pauly
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Conor L Rooney
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Chungseok Choi
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Bo Shang
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Scott McGuigan
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Majed S Fataftah
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Yves Kayser
- Max Planck Institute for Chemical Energy Conversion, D-45470 Mülheim an der Ruhr, Germany
| | - Simon C B Suhr
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion, D-45470 Mülheim an der Ruhr, Germany
| | - Hailiang Wang
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Paul A Maggard
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Patrick L Holland
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
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Ferentinos E, Tzeli D, Sottini S, Groenen EJJ, Ozerov M, Poneti G, Kaniewska-Laskowska K, Krzystek J, Kyritsis P. Magnetic anisotropy and structural flexibility in the field-induced single ion magnets [Co{(OPPh 2)(EPPh 2)N} 2], E = S, Se, explored by experimental and computational methods. Dalton Trans 2023; 52:2036-2050. [PMID: 36692040 PMCID: PMC9926333 DOI: 10.1039/d2dt03335f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 01/14/2023] [Indexed: 01/25/2023]
Abstract
During the last few years, a large number of mononuclear Co(II) complexes of various coordination geometries have been explored as potential single ion magnets (SIMs). In the work presented herein, the Co(II) S = 3/2 tetrahedral [Co{(OPPh2)(EPPh2)N}2], E = S, Se, complexes (abbreviated as CoO2E2), bearing chalcogenated mixed donor-atom imidodiphosphinato ligands, were studied by both experimental and computational techniques. Specifically, direct current (DC) magnetometry provided estimations of their zero-field splitting (zfs) axial (D) and rhombic (E) parameter values, which were more accurately determined by a combination of far-infrared magnetic spectroscopy and high-frequency and -field EPR spectroscopy studies. The latter combination of techniques was also implemented for the S = 3/2 tetrahedral [Co{(EPiPr2)2N}2], E = S, Se, complexes, confirming the previously determined magnitude of their zfs parameters. For both pairs of complexes (E = S, Se), it is concluded that the identity of the E donor atom does not significantly affect their zfs parameters. High-resolution multifrequency EPR studies of CoO2E2 provided evidence of multiple conformations, which are more clearly observed for CoO2Se2, in agreement with the structural disorder previously established for this complex by X-ray crystallography. The CoO2E2 complexes were shown to be field-induced SIMs, i.e., they exhibit slow relaxation of magnetization in the presence of an external DC magnetic field. Advanced quantum-chemical calculations on CoO2E2 provided additional insight into their electronic and structural properties.
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Affiliation(s)
- Eleftherios Ferentinos
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, GR-15771 Athens, Greece.
| | - Demeter Tzeli
- Physical Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, GR-15771 Athens, Greece
- Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vassileos Constantinou Ave., GR-11635 Athens, Greece
| | - Silvia Sottini
- Huygens-Kamerlingh Onnes Laboratory, Department of Physics, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
| | - Edgar J J Groenen
- Huygens-Kamerlingh Onnes Laboratory, Department of Physics, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
| | - Mykhaylo Ozerov
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.
| | - Giordano Poneti
- Instituto de Química, Universidade Federal do Rio de Janeiro, 21941-909 Rio de Janeiro, Brazil.
| | - Kinga Kaniewska-Laskowska
- Department of Inorganic Chemistry, Faculty of Chemistry, Gdańsk University of Technology, G. Narutowicza St. 11/12, Gdańsk PL-80-233, Poland
| | - J Krzystek
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.
| | - Panayotis Kyritsis
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, GR-15771 Athens, Greece.
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