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Mato M, Cornella J. Bismuth in Radical Chemistry and Catalysis. Angew Chem Int Ed Engl 2024; 63:e202315046. [PMID: 37988225 DOI: 10.1002/anie.202315046] [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: 10/07/2023] [Revised: 11/20/2023] [Accepted: 11/21/2023] [Indexed: 11/23/2023]
Abstract
Whereas indications of radical reactivity in bismuth compounds can be traced back to the 19th century, the preparation and characterization of both transient and persistent bismuth-radical species has only been established in recent decades. These advancements led to the emergence of the field of bismuth radical chemistry, mirroring the progress seen for other main-group elements. The seminal and fundamental studies in this area have ultimately paved the way for the development of catalytic methodologies involving bismuth-radical intermediates, a promising approach that remains largely untapped in the broad landscape of synthetic organic chemistry. In this review, we delve into the milestones that eventually led to the present state-of-the-art in the field of radical bismuth chemistry. Our focus aims at outlining the intrinsic discoveries in fundamental inorganic/organometallic chemistry and contextualizing their practical applications in organic synthesis and catalysis.
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Affiliation(s)
- Mauro Mato
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Josep Cornella
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
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2
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Sharma MK, Weinert HM, Li B, Wölper C, Henthorn JT, Cutsail GE, Haberhauer G, Schulz S. Syntheses and Structures of 5-Membered Heterocycles Featuring 1,2-Diphospha-1,3-Butadiene and Its Radical Anion. Angew Chem Int Ed Engl 2023; 62:e202309466. [PMID: 37582227 DOI: 10.1002/anie.202309466] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 08/13/2023] [Accepted: 08/15/2023] [Indexed: 08/17/2023]
Abstract
LGa(P2 OC)cAAC 2 features a 1,2-diphospha-1,3-butadiene unit with a delocalized π-type HOMO and a π*-type LUMO according to DFT calculations. [LGa(P2 OC)cAAC][K(DB-18-c-6)] 3[K(DB-18-c-6] containing the 1,2-diphospha-1,3-butadiene radical anion 3⋅- was isolated from the reaction of 2 with KC8 and dibenzo-18-crown-6. 3 reacted with [Fc][B(C6 F5 )4 ] (Fc=ferrocenium) to 2 and with TEMPO to [L-H Ga(P2 OC)cAAC][K(DB-18-c-6)] 4[K(DB-18-c-6] containing the 1,2-diphospha-1,3-butadiene anion 4- . The solid state structures of 2, 3K(DB-18-c-6], and 4[K(DB-18-c-6] were determined by single crystal X-ray diffraction (sc-XRD).
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Affiliation(s)
- Mahendra K Sharma
- Institute of Inorganic Chemistry, University of Duisburg-Essen, Universitätsstraße 5-7, 45141, Essen, Germany
| | - Hanns M Weinert
- Institute of Inorganic Chemistry, University of Duisburg-Essen, Universitätsstraße 5-7, 45141, Essen, Germany
| | - Bin Li
- Institute of Inorganic Chemistry, University of Duisburg-Essen, Universitätsstraße 5-7, 45141, Essen, Germany
| | - Christoph Wölper
- Institute of Inorganic Chemistry, University of Duisburg-Essen, Universitätsstraße 5-7, 45141, Essen, Germany
| | - Justin T Henthorn
- Max Planck Institute for Chemical Energy Conversion (MPI-CEC), Stiftstrasse 34-36, 45470, Mülheim an der Ruhr, Germany
| | - George E Cutsail
- Max Planck Institute for Chemical Energy Conversion (MPI-CEC), Stiftstrasse 34-36, 45470, Mülheim an der Ruhr, Germany
| | - Gebhard Haberhauer
- Institute of Organic Chemistry, University of Duisburg-Essen, Universitätsstraße 5-7, 45141, Essen, Germany
| | - Stephan Schulz
- Institute of Inorganic Chemistry, University of Duisburg-Essen, Universitätsstraße 5-7, 45141, Essen, Germany
- Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Carl-Benz-Straße 199, 47057, Duisburg, Germany
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3
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Abstract
Heteroatom-centered diradical(oid)s have been in the focus of molecular main group chemistry for nearly 30 years. During this time, the diradical concept has evolved and the focus has shifted to the rational design of diradical(oid)s for specific applications. This review article begins with some important theoretical considerations of the diradical and tetraradical concept. Based on these theoretical considerations, the design of diradical(oid)s in terms of ligand choice, steric, symmetry, electronic situation, element choice, and reactivity is highlighted with examples. In particular, heteroatom-centered diradical reactions are discussed and compared with closed-shell reactions such as pericyclic additions. The comparison between closed-shell reactivity, which proceeds in a concerted manner, and open-shell reactivity, which proceeds in a stepwise fashion, along with considerations of diradical(oid) design, provides a rational understanding of this interesting and unusual class of compounds. The application of diradical(oid)s, for example in small molecule activation or as molecular switches, is also highlighted. The final part of this review begins with application-related details of the spectroscopy of diradical(oid)s, followed by an update of the heteroatom-centered diradical(oid)s and tetraradical(oid)s published in the last 10 years since 2013.
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Affiliation(s)
- Alexander Hinz
- Institut für Anorganische Chemie (AOC), Karlsruher Institut für Technologie (KIT), Engesserstrasse 15, 76131 Karlsruhe, Germany
| | - Jonas Bresien
- Institut für Chemie, Universität Rostock, Albert-Einstein-Strasse 3a, 18059 Rostock, Germany
| | - Frank Breher
- Institut für Anorganische Chemie (AOC), Karlsruher Institut für Technologie (KIT), Engesserstrasse 15, 76131 Karlsruhe, Germany
| | - Axel Schulz
- Institut für Chemie, Universität Rostock, Albert-Einstein-Strasse 3a, 18059 Rostock, Germany
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4
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Titova YY. Dynamic EPR Studies of the Formation of Catalytically Active Centres in Multicomponent Hydrogenation Systems. Catalysts 2023. [DOI: 10.3390/catal13040653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023] Open
Abstract
The formation of catalytically active nano-sized cobalt-containing structures in multicomponent hydrogenation systems based on Co(acac)2 complex and various cocatalysts, namely, AlEt3, AlEt2(OEt), Li-n-Bu, and (PhCH2)MgCl, has been studied for the first time in detail using dynamic EPR spectroscopy. It is shown that after mixing the initial components, paramagnetic structures are formed, which include a fragment containing Co(0) with the electronic configuration 3d9, as well as a fragment bearing an aluminium, lithium, or magnesium atom, depending on the nature of the used cocatalyst. Such bimetallic paramagnetic sites are stabilized by acetylacetonate ligands. In addition, the paramagnetic complex contains the arene molecule(s), and the cobalt atom is bonded with the atom of the corresponding non-transition through the alkyl group of the co-catalyst, in particular through the carbon atom in the α-position with respect to the atom of the non-transition element. Due to the high reactivity of the described intermediates, they, under the conditions of hydrogenation catalysis, are transformed into nano-sized cobalt-containing structures that act as carriers of the catalytically active sites. Furthermore, because of the high reactivity and paramagnetism, such intermediates can be detected only by the EPR technique. The paper describes the whole experimental way of interpreting the EPR signals corresponding to the intermediates, precursors of catalytically active structures. In addition, a possible mathematical model based on the obtained experimental EPR data is presented.
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5
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Yang X, Reijerse EJ, Nöthling N, SantaLucia DJ, Leutzsch M, Schnegg A, Cornella J. Synthesis, Isolation, and Characterization of Two Cationic Organobismuth(II) Pincer Complexes Relevant in Radical Redox Chemistry. J Am Chem Soc 2023; 145:5618-5623. [PMID: 36854169 PMCID: PMC10021010 DOI: 10.1021/jacs.2c12564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
Herein, we report the synthesis, isolation, and characterization of two cationic organobismuth(II) compounds bearing N,C,N pincer frameworks, which model crucial intermediates in bismuth radical processes. X-ray crystallography uncovered a monomeric Bi(II) structure, while SQUID magnetometry in combination with NMR and EPR spectroscopy provides evidence for a paramagnetic S = 1/2 state. High-resolution multifrequency EPR at the X-, Q-, and W-band enable the precise assignment of the full g- and 209Bi A-tensors. Experimental data and DFT calculations reveal both complexes are metal-centered radicals with little delocalization onto the ligands.
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Affiliation(s)
- Xiuxiu Yang
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Edward J Reijerse
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470, Mülheim an der Ruhr, Germany
| | - Nils Nöthling
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Daniel J SantaLucia
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Markus Leutzsch
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Alexander Schnegg
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470, Mülheim an der Ruhr, Germany
| | - Josep Cornella
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
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6
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Lehr A, Rivic F, Schäfer R. Enhanced Electronic g-Factors in Magic Number Main Group Bimetallic Nanoclusters. J Am Chem Soc 2023; 145:2070-2074. [PMID: 36656622 DOI: 10.1021/jacs.2c12959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
We report the observation of large electronic g-factors in magic number main group bimetallic nanoclusters by performing Stern-Gerlach deflection experiments at 10 K. The clusters AlPb12 and InPb12 exhibit values of g = 3.5-4.0, whereas GaPb12 clusters surprisingly reveal a value of g < 2.0. Multireference ab initio methods are applied to unmask the origin of the g-factors and to gain insight into the electronic structure. The interplay of the pyritohedral molecular symmetry, a particularly strong spin-orbit coupling involved in the ground state, and the presence of low-lying degenerate excited states causes large positive g-factors in AlPb12 and InPb12. Contrarily, the spin-orbit coupling in the GaPb12 ground state is completely quenched. This is due to the d-block contraction lowering the nonbonding Ga 5s orbital and consequently forming an icosahedral ground state. Thus, endohedral p-doped tetrel clusters, composed of purely main group elements, state a novel and unique class of magnetic compounds and their study contributes to a more profound understanding of the metal-metal interaction in polynuclear clusters as well as magnetism at the molecular level.
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Affiliation(s)
- Andreas Lehr
- Eduard-Zintl Institute, Technical University of Darmstadt, Alarich-Weiss-Straße 8, 64287Darmstadt, Germany
| | - Filip Rivic
- Eduard-Zintl Institute, Technical University of Darmstadt, Alarich-Weiss-Straße 8, 64287Darmstadt, Germany
| | - Rolf Schäfer
- Eduard-Zintl Institute, Technical University of Darmstadt, Alarich-Weiss-Straße 8, 64287Darmstadt, Germany
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7
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Liu YH, Li CC, Cheng WK, Li YH, Lin RY, Shieh M. Paramagnetic Semiconducting Se–Mn Clusters: A Mn 3Se 4-Stabilized Selenide Radical Intermediate and Its Aggregated Derivatives. Inorg Chem 2022; 61:20433-20444. [DOI: 10.1021/acs.inorgchem.2c03080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Yu-Hsin Liu
- Department of Chemistry, National Taiwan Normal University, Taipei, Taiwan116325, Republic of China
| | - Cai-Cen Li
- Department of Chemistry, National Taiwan Normal University, Taipei, Taiwan116325, Republic of China
| | - Wen-Kai Cheng
- Department of Chemistry, National Taiwan Normal University, Taipei, Taiwan116325, Republic of China
| | - Yu-Huei Li
- Department of Chemistry, National Taiwan Normal University, Taipei, Taiwan116325, Republic of China
| | - Ru Yan Lin
- Department of Chemistry, National Taiwan Normal University, Taipei, Taiwan116325, Republic of China
| | - Minghuey Shieh
- Department of Chemistry, National Taiwan Normal University, Taipei, Taiwan116325, Republic of China
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8
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Telser J. Linewidth, field, and frequency in electron paramagnetic resonance (EPR) spectroscopy. J Biol Inorg Chem 2022; 27:605-609. [DOI: 10.1007/s00775-022-01961-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 08/31/2022] [Indexed: 10/14/2022]
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9
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Dai Y, Bao M, Wang W, Xie Z, Liu C, Su Y. Crystalline
Germanium‐Dipyrromethene
Radicals: from a Delocalized Neutral to a Localized Cation. CHINESE J CHEM 2022. [DOI: 10.1002/cjoc.202200431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Yuyang Dai
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection Soochow University Suzhou 215123 China
| | - Manling Bao
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection Soochow University Suzhou 215123 China
| | - Wenjuan Wang
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection Soochow University Suzhou 215123 China
| | - Zhuofeng Xie
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection Soochow University Suzhou 215123 China
| | - Chunmeng Liu
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection Soochow University Suzhou 215123 China
| | - Yuanting Su
- College of Chemistry, Chemical Engineering and Materials Science, School of Radiation Medicine and Protection Soochow University Suzhou 215123 China
- State Key Laboratory of Coordination Chemistry Nanjing University Nanjing 210023 China
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10
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Haak J, Krüger J, Abrosimov NV, Helling C, Schulz S, Cutsail Iii GE. X-Band Parallel-Mode and Multifrequency Electron Paramagnetic Resonance Spectroscopy of S = 1/2 Bismuth Centers. Inorg Chem 2022; 61:11173-11181. [PMID: 35834368 PMCID: PMC9326968 DOI: 10.1021/acs.inorgchem.2c01141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The recent successes in the isolation and characterization of several bismuth radicals inspire the development of new spectroscopic approaches for the in-depth analysis of their electronic structure. Electron paramagnetic resonance (EPR) spectroscopy is a powerful tool for the characterization of main group radicals. However, the large electron-nuclear hyperfine interactions of Bi (209Bi, I = 9/2) have presented difficult challenges to fully interpret the spectral properties for some of these radicals. Parallel-mode EPR (B1∥B0) is almost exclusively employed for the study of S > 1/2 systems but becomes feasible for S = 1/2 systems with large hyperfine couplings, offering a distinct EPR spectroscopic approach. Herein, we demonstrate the application of conventional X-band parallel-mode EPR for S = 1/2, I = 9/2 spin systems: Bi-doped crystalline silicon (Si:Bi) and the molecular Bi radicals [L(X)Ga]2Bi• (X = Cl or I) and [L(Cl)GaBi(MecAAC)]•+ (L = HC[MeCN(2,6-iPr2C6H3)]2). In combination with multifrequency perpendicular-mode EPR (X-, Q-, and W-band frequencies), we were able to fully refine both the anisotropic g- and A-tensors of these molecular radicals. The parallel-mode EPR experiments demonstrated and discussed here have the potential to enable the characterization of other S = 1/2 systems with large hyperfine couplings, which is often challenging by conventional perpendicular-mode EPR techniques. Considerations pertaining to the choice of microwave frequency are discussed for relevant spin-systems.
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Affiliation(s)
- Julia Haak
- Max Planck Institute for Chemical Energy Conversion (CEC), Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany.,Institute of Inorganic Chemistry, University of Duisburg-Essen, Universitätsstraße 5-7, 45141 Essen, Germany
| | - Julia Krüger
- Institute of Inorganic Chemistry, University of Duisburg-Essen, Universitätsstraße 5-7, 45141 Essen, Germany.,Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitätsstraße 5-7, 45141 Essen, Germany
| | - Nikolay V Abrosimov
- Leibniz-Institut für Kristallzüchtung, Max-Born Strasse 2, 12489 Berlin, Germany
| | - Christoph Helling
- Institute of Inorganic Chemistry, University of Duisburg-Essen, Universitätsstraße 5-7, 45141 Essen, Germany.,Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitätsstraße 5-7, 45141 Essen, Germany
| | - Stephan Schulz
- Institute of Inorganic Chemistry, University of Duisburg-Essen, Universitätsstraße 5-7, 45141 Essen, Germany.,Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitätsstraße 5-7, 45141 Essen, Germany
| | - George E Cutsail Iii
- Max Planck Institute for Chemical Energy Conversion (CEC), Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany.,Institute of Inorganic Chemistry, University of Duisburg-Essen, Universitätsstraße 5-7, 45141 Essen, Germany
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11
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12
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Krüger J, Haak J, Wölper C, Cutsail GE, Haberhauer G, Schulz S. Single-Electron Oxidation of Carbene-Coordinated Pnictinidenes-Entry into Heteroleptic Radical Cations and Metalloid Clusters. Inorg Chem 2022; 61:5878-5884. [PMID: 35333051 DOI: 10.1021/acs.inorgchem.2c00249] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Stable heavy main group element radicals are challenging synthetic targets. Although several strategies have been developed to stabilize such odd-electron species, the number of heavier pnictogen-centered radicals is limited. We report on a series of two-coordinated pnictogen-centered radical cations [(MecAAC)EGa(Cl)L][B(C6F5)4] (MecAAC = [H2C(CMe2)2NDipp]C; Dipp = 2,6-i-Pr2C6H3; E = As 1, Sb 2, Bi 3; L = HC[C(Me)NDipp]2) synthesized by one-electron oxidation of L(Cl)Ga-substituted pnictinidenes (MecAAC)EGa(Cl)L (E = As I, Sb II, Bi III). 1-3 were characterized by electron paramagnetic resonance (EPR) spectroscopy and single crystal X-ray diffraction (sc-XRD) (1, 2), while quantum chemical calculations support their description as carbene-coordinated pnictogen-centered radical cations. The low thermal stability of 3 enables access to metalloid bismuth clusters as shown by formation of [{LGa(Cl)}3Bi6][B(C6F5)4] (4).
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Affiliation(s)
- Julia Krüger
- Institute of Inorganic Chemistry, University of Duisburg-Essen, Universitätsstraße 5-7, 45141 Essen, Germany
| | - Julia Haak
- Max Planck Institute for Chemical Energy Conversion (CEC), Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Christoph Wölper
- Institute of Inorganic Chemistry, University of Duisburg-Essen, Universitätsstraße 5-7, 45141 Essen, Germany
| | - George E Cutsail
- Institute of Inorganic Chemistry, University of Duisburg-Essen, Universitätsstraße 5-7, 45141 Essen, Germany.,Max Planck Institute for Chemical Energy Conversion (CEC), Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Gebhard Haberhauer
- Institute of Organic Chemistry, University of Duisburg-Essen, Universitätsstraße 5-7, 45141 Essen, Germany
| | - Stephan Schulz
- Institute of Inorganic Chemistry, University of Duisburg-Essen, Universitätsstraße 5-7, 45141 Essen, Germany.,Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Carl-Benz-Straße 199, 47057 Duisburg, Germany
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13
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Helling C, Haak J, Wölper C, Cutsail GE, Schulz S. Sequential Reduction of Borylstibane to an Electronically Nonsymmetric Diboryldistibene Radical Anion. Inorg Chem 2022; 61:5124-5132. [PMID: 35293742 DOI: 10.1021/acs.inorgchem.2c00251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Understanding the formation of metal-metal bonds and their electronic structures is still a scientific task. We herein report on the stepwise synthesis of boryl-substituted antimony compounds in which the antimony atoms adopt four different oxidation states (+III, +II, +I, +I/0). Sb-C bond homolysis of Cp*[(HCNDip)2B]SbCl (1; Cp* = C5Me5; Dip = 2,6-iPr2C6H3) gave diboryldichlorodistibane [(HCNDip)2BSbCl]2 (2), which reacted with KC8 to form diboryldistibene [(HCNDip)2BSb]2 (3) and traces of cyclotetrastibane [(HCNDip)2B]3Sb4Cl (5). One-electron reduction of 3 yielded the potassium salt of the diboryldistibene radical anion [(HCNDip)2BSb]2̇-, [K(18-c-6)(OEt2)][{(HCNDip)2BSb}2] (4), which exhibits an unprecedented inequivalent spin localization on the Sb-Sb bond and hence an unsymmetric electronic structure. Compounds 1-4 were characterized by heteronuclear nuclear magnetic resonance (NMR) (1H, 13C, 11B), infrared (IR), ultraviolet-visible (UV-vis) spectroscopy (3, 4), and single crystal X-ray diffraction (sc-XRD, 1-5), while the bonding nature of 3 and 4 was analyzed by quantum chemical calculations. EPR spectroscopy resolves the dissimilar Sb hyperfine tensors of 4, reflecting the inequivalent spin distribution, setting 4 uniquely apart from all previously characterized dipnictene radical anions.
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Affiliation(s)
- Christoph Helling
- Institute for Inorganic Chemistry, University of Duisburg-Essen, 45117 Essen, Germany
| | - Julia Haak
- Max Planck Institute for Chemical Energy Conversion (CEC), 45470 Mülheim an der Ruhr, Germany
| | - Christoph Wölper
- Institute for Inorganic Chemistry, University of Duisburg-Essen, 45117 Essen, Germany
| | - George E Cutsail
- Institute for Inorganic Chemistry, University of Duisburg-Essen, 45117 Essen, Germany.,Max Planck Institute for Chemical Energy Conversion (CEC), 45470 Mülheim an der Ruhr, Germany
| | - Stephan Schulz
- Institute for Inorganic Chemistry, University of Duisburg-Essen, 45117 Essen, Germany.,Center for Nanointegration Duisburg Essen (CENIDE), University of Duisburg-Essen, 47057 Duisburg, Germany
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14
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Kundu K, White JRK, Moehring SA, Yu JM, Ziller JW, Furche F, Evans WJ, Hill S. A 9.2-GHz clock transition in a Lu(II) molecular spin qubit arising from a 3,467-MHz hyperfine interaction. Nat Chem 2022; 14:392-397. [PMID: 35288686 DOI: 10.1038/s41557-022-00894-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 01/13/2022] [Indexed: 11/09/2022]
Abstract
Spins in molecules are particularly attractive targets for next-generation quantum technologies, enabling chemically programmable qubits and potential for scale-up via self-assembly. Here we report the observation of one of the largest hyperfine interactions for a molecular system, Aiso = 3,467 ± 50 MHz, as well as a very large associated clock transition. This is achieved through chemical control of the degree of s-orbital mixing into the spin-bearing d orbital associated with a series of spin-½ La(II) and Lu(II) complexes. Increased s-orbital character reduces spin-orbit coupling and enhances the electron-nuclear Fermi contact interaction. Both outcomes are advantageous for quantum applications. The former reduces spin-lattice relaxation, and the latter maximizes the hyperfine interaction, which, in turn, generates a 9-GHz clock transition, leading to an increase in phase memory time from 1.0 ± 0.4 to 12 ± 1 μs for one of the Lu(II) complexes. These findings suggest strategies for the development of molecular quantum technologies, akin to trapped ion systems.
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Affiliation(s)
- Krishnendu Kundu
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA
| | | | | | - Jason M Yu
- Department of Chemistry, University of California, Irvine, CA, USA
| | - Joseph W Ziller
- Department of Chemistry, University of California, Irvine, CA, USA
| | - Filipp Furche
- Department of Chemistry, University of California, Irvine, CA, USA.
| | - William J Evans
- Department of Chemistry, University of California, Irvine, CA, USA.
| | - Stephen Hill
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA. .,Department of Physics, Florida State University, Tallahassee, FL, USA.
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15
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Hyperfine Decoupling of ESR Spectra Using Wavelet Transform. MAGNETOCHEMISTRY 2022. [PMID: 37475982 PMCID: PMC10357921 DOI: 10.3390/magnetochemistry8030032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The objective of spectral analysis is to resolve and extract relevant features from experimental data in an optimal fashion. In continuous-wave (cw) electron spin resonance (ESR) spectroscopy, both g values of a paramagnetic center and hyperfine splitting (A) caused by its interaction with neighboring magnetic nuclei in a molecule provide important structural and electronic information. However, in the presence of g- and/or A-anisotropy and/or large number of resonance lines, spectral analysis becomes highly challenging. Either high-resolution experimental techniques are employed to resolve the spectra in those cases or a range of suitable ESR frequencies are used in combination with simulations to identify the corresponding g and A values. In this work, we present a wavelet transform technique in resolving both simulated and experimental cw-ESR spectra by separating the hyperfine and super-hyperfine components. We exploit the multiresolution property of wavelet transforms that allow the separation of distinct features of a spectrum based on simultaneous analysis of spectrum and its varying frequency. We retain the wavelet components that stored the hyperfine and/or super-hyperfine features, while eliminating the wavelet components representing the remaining spectrum. We tested the method on simulated cases of metal–ligand adducts at L-, S-, and X-band frequencies, and showed that extracted g values, hyperfine and super-hyperfine coupling constants from simulated spectra, were in excellent agreement with the values of those parameters used in the simulations. For the experimental case of a copper(II) complex with distorted octahedral geometry, the method was able to extract g and hyperfine coupling constant values, and revealed features that were buried in the overlapped spectra.
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16
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Legendre CM, Stückl AC, Sindlinger CP, Herbst‐Irmer R, Stalke D. Isolation and Properties of the Long Elusive Deep Blue Soluble [K
3
{(N
t
Bu)
3
S}
2
]
.
Cage Radical. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202115026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Christina M. Legendre
- Georg-August Universität Göttingen Institut für Anorganische Chemie Tammannstraße 4 37077 Göttingen Germany
| | - A. Claudia Stückl
- Georg-August Universität Göttingen Institut für Anorganische Chemie Tammannstraße 4 37077 Göttingen Germany
| | - Christian P. Sindlinger
- Georg-August Universität Göttingen Institut für Anorganische Chemie Tammannstraße 4 37077 Göttingen Germany
| | - Regine Herbst‐Irmer
- Georg-August Universität Göttingen Institut für Anorganische Chemie Tammannstraße 4 37077 Göttingen Germany
| | - Dietmar Stalke
- Georg-August Universität Göttingen Institut für Anorganische Chemie Tammannstraße 4 37077 Göttingen Germany
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17
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Li B, Geoghegan B, Weinert HM, Wölper C, Cutsail III G, Schulz S. Synthesis and redox activity of carbene-coordinated group 13 metal radicals. Chem Commun (Camb) 2022; 58:4372-4375. [DOI: 10.1039/d2cc00216g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Carbenes are known to stabilize main group element compounds with unusual electronic properties. Herein, we report the synthesis of carbene-stabilized group 13 metal radicals (cAAC)MX2(IPr) (M = Al, X =...
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18
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Sieg G, Fischer MM, Dankert F, Siewert JE, Hering-Junghans C, Werncke G. A Diarsene Radical Anion. Chem Commun (Camb) 2022; 58:9786-9789. [DOI: 10.1039/d2cc03237f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The isolation of the first diarsene radical anion by reduction of a neutral diarsene is presented. Comprehensive characterisation in conjunction with DFT calculations reveal unpaired spin density residing in the...
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19
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Ramler J, Schwarzmann J, Stoy A, Lichtenberg C. Two Faces of the Bi−O Bond: Photochemically
and
Thermally Induced Dehydrocoupling for Si−O Bond Formation. Eur J Inorg Chem 2021; 2022:e202100934. [PMID: 35873275 PMCID: PMC9300068 DOI: 10.1002/ejic.202100934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/23/2021] [Indexed: 11/27/2022]
Abstract
The diorgano(bismuth)alcoholate [Bi((C6H4CH2)2S)OPh] (1‐OPh) has been synthesized and fully characterized. Stoichiometric reactions, UV/Vis spectroscopy, and (TD‐)DFT calculations suggest its susceptibility to homolytic and heterolytic Bi−O bond cleavage under given reaction conditions. Using the dehydrocoupling of silanes with either TEMPO or phenol as model reactions, the catalytic competency of 1‐OPh has been investigated (TEMPO=(tetramethyl‐piperidin‐1‐yl)‐oxyl). Different reaction pathways can deliberately be addressed by applying photochemical or thermal reaction conditions and by choosing radical or closed‐shell substrates (TEMPO vs. phenol). Applied analytical techniques include NMR, UV/Vis, and EPR spectroscopy, mass spectrometry, single‐crystal X‐ray diffraction analysis, and (TD)‐DFT calculations.
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Affiliation(s)
- Jacqueline Ramler
- Institute of Inorganic Chemistry Julius-Maximilians-University Würzburg Am Hubland 97074 Würzburg Germany
| | - Johannes Schwarzmann
- Institute of Inorganic Chemistry Julius-Maximilians-University Würzburg Am Hubland 97074 Würzburg Germany
| | - Andreas Stoy
- Institute of Inorganic Chemistry Julius-Maximilians-University Würzburg Am Hubland 97074 Würzburg Germany
- Philipps-Universität Marburg Fachbereich Chemie Hans-Meerwein-Str. 4 35032 Marburg Germany
| | - Crispin Lichtenberg
- Institute of Inorganic Chemistry Julius-Maximilians-University Würzburg Am Hubland 97074 Würzburg Germany
- Philipps-Universität Marburg Fachbereich Chemie Hans-Meerwein-Str. 4 35032 Marburg Germany
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20
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Stalke D, Legendre CM, Stückl AC, Sindlinger CP, Herbst-Irmer R. Isolation and properties of the long elusive ultramarine-blue soluble [K3{(NtBu)3S}2]··cage radical. Angew Chem Int Ed Engl 2021; 61:e202115026. [PMID: 34905651 PMCID: PMC9306764 DOI: 10.1002/anie.202115026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Indexed: 12/05/2022]
Abstract
The reaction of potassium metal with sulfurtriimide S(NtBu)3 (II) gives the long elusive deep blue cage radical [K3{(NtBu)3S}2]. (1_K) that crystallizes at −35 °C from toluene solution. The subsequent physical characterization via X‐ray structure analysis, UV/Vis‐, and EPR spectroscopy from solution reveals the existence of one unpaired electron delocalized within the whole cage, i.e. coupling with the six nitrogen atoms, as well as the three potassium atoms caped by the two SN3 ligands. The present X‐ray structure analysis further supports previous assumptions made on the parent compound 1_Li obtained from [Li4{(NtBu)3S}2] (I) and finally elucidates the structural arrangement of the SN3 caps and alkali metals in such radical cage species.
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Affiliation(s)
- Dietmar Stalke
- Universität Göttingen, Institut für Anorganische und Analytische Chemie, Tammannstraße 4, 37077, Göttingen, GERMANY
| | - Christina M Legendre
- Georg-August-Universität Göttingen: Georg-August-Universitat Gottingen, Institut für Anorganische Chemie, GERMANY
| | - A Claudia Stückl
- Georg-August-Universität Göttingen: Georg-August-Universitat Gottingen, Institut für Anorganische Chemie, GERMANY
| | - Christian P Sindlinger
- Georg-August-Universität Göttingen: Georg-August-Universitat Gottingen, Institut für Anorganische Chemie, GERMANY
| | - Regine Herbst-Irmer
- Georg-August-Universität Göttingen: Georg-August-Universitat Gottingen, Institur für Anorganische Chemie, GERMANY
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21
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Gericke R, Wagler J. Coordination and Electrochemical Switching on Paddle-Wheel Complexes Containing an As-Ru or a Sb-Ru Axis. Inorg Chem 2021; 60:18122-18132. [PMID: 34813693 DOI: 10.1021/acs.inorgchem.1c02735] [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
Inspired by the known complex [PhP(μ-PyO)4Ru(CO)] (PyO = 2-pyridyloxy), the family of group 15 paddle-wheel complexes has been expanded to [PhPn(μ-PyO)4Ru(L)] (Pn = P, As, Sb; L = NCMe, CO). Solvent-dependent reversible switching between [PhAs(μ-PyO)4Ru(NCMe)] and [PhAs(μ-PyO)3Ru(κ2-PyO)] was detected. Electrochemical investigations of the [PhPn(μ-PyO)4Ru(L)] complexes showed reversible oxidation of the complexes with L = NCMe and back-formation of the complexes with L = NCMe upon oxidation of the complexes with L = CO in NCMe. In the series of [PhPn(μ-PyO)4Ru(L)] complexes, the Pn→Ru bonding mode is shifted from L-type Pn to X-type upon going from Pn = P and As to Pn = Sb, resulting in a pronounced electron-rich Ru site in the latter case. The easily accessible complex [PhSb(μ-PyO)4RuCl] exhibits reversible electrochemical and coordinative exchange with its reduced analogue [PhSb(μ-PyO)4Ru(NCMe)] under retention of the paddle-wheel motif and Sb-Ru bond properties.
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Affiliation(s)
- Robert Gericke
- Institut für Anorganische Chemie, Technische Universität Bergakademie Freiberg, Leipziger Straße 29, D-09596 Freiberg, Germany.,Institute of Resource Ecology, Helmholtz-Zentrum Dresden-Rossendorf eV, Bautzner Landstrasse 400, D-01328 Dresden, Germany
| | - Jörg Wagler
- Institut für Anorganische Chemie, Technische Universität Bergakademie Freiberg, Leipziger Straße 29, D-09596 Freiberg, Germany
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22
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Weinert HM, Wölper C, Haak J, Cutsail GE, Schulz S. Synthesis, structure and bonding nature of heavy dipnictene radical anions. Chem Sci 2021; 12:14024-14032. [PMID: 34760185 PMCID: PMC8565390 DOI: 10.1039/d1sc04230k] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 08/28/2021] [Indexed: 12/02/2022] Open
Abstract
Cyclic voltammetry (CV) studies of two L(X)Ga-substituted dipnictenes [L(R2N)GaE]2 (E = Sb, R = Me 1; E = Bi; R = Et 2; L = HC[C(Me)NDipp]2; Dipp = 2,6-i-Pr2C6H3) showed reversible reduction events. Single electron reduction of 1 and 2 with KC8 in DME in the presence of benzo-18-crown-6 (B-18-C-6) gave the corresponding dipnictenyl radical anions (DME)[K(B-18-C-6)][L(R2N)GaE]2 (E = Sb, R = Me 3; E = Bi, R = Et 4). Radical anions 3 and 4 were characterized by EPR, UV-vis and single crystal X-ray diffraction, while quantum chemical calculations gave deeper insight into the nature of the chemical bonding.
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Affiliation(s)
- Hanns M Weinert
- Institute for Inorganic Chemistry, Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen Universitätsstraße 5-7 45117 Essen Germany
| | - Christoph Wölper
- Institute for Inorganic Chemistry, Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen Universitätsstraße 5-7 45117 Essen Germany
| | - Julia Haak
- Institute for Inorganic Chemistry, Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen Universitätsstraße 5-7 45117 Essen Germany
- Max Planck Institute for Chemical Energy Conversion (CEC) Stiftstraße 34-36 45470 Mülheim a. d. Ruhr Germany
| | - George E Cutsail
- Institute for Inorganic Chemistry, Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen Universitätsstraße 5-7 45117 Essen Germany
- Max Planck Institute for Chemical Energy Conversion (CEC) Stiftstraße 34-36 45470 Mülheim a. d. Ruhr Germany
| | - Stephan Schulz
- Institute for Inorganic Chemistry, Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen Universitätsstraße 5-7 45117 Essen Germany
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23
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Witwicki M, Lewińska A, Ozarowski A. o-Semiquinone radical anion isolated as an amorphous porous solid. Phys Chem Chem Phys 2021; 23:17408-17419. [PMID: 34351330 DOI: 10.1039/d1cp01596f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The use of metal cations is a commonly applied strategy to create S > 1/2 stable molecular systems containing semiquinone radicals. Persistent mono-semiquinonato complexes of diamagnetic metal ions (S = 1/2) have been hitherto less common and mostly limited to the complexes of heavy metal ions. In this work, a mono-semiquinonato complex of aluminum, derived from 1,2-dihydroxybenzene, is obtained using a surprisingly short and uncomplicated procedure. The isolated product is an amorphous and porous solid that exhibits very good stability under ambient conditions. To characterise its molecular and electronic structure, 9.7, 34 and 406 GHz EPR spectroscopy was used in concert with computational techniques (DFT and DLPNO-CCSD). It was revealed that the radical complex is composed of two chemically equivalent aluminum cations and two catechol-like ligands with the unpaired electron uniformly distributed between the two organic molecules. The good stability and porous structure make this complex applicable in heterogeneous aerobic reactions.
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Affiliation(s)
- Maciej Witwicki
- Faculty of Chemistry, Wroclaw University, Joliot-Curie 14, 50-383 Wroclaw, Poland.
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24
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Lewińska A, Kulbacka J, Domżał-Kędzia M, Witwicki M. Antiradical Properties of N-Oxide Surfactants-Two in One. Int J Mol Sci 2021; 22:ijms22158040. [PMID: 34360806 PMCID: PMC8346996 DOI: 10.3390/ijms22158040] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/14/2021] [Accepted: 07/22/2021] [Indexed: 12/26/2022] Open
Abstract
Surfactants are molecules that lower surface or interfacial tension, and thus they are broadly used as detergents, wetting agents, emulsifiers, foaming agents, or dispersants. However, for modern applications, substances that can perform more than one function are desired. In this study we evaluated antioxidant properties of two homological series of N-oxide surfactants: monocephalic 3-(alkanoylamino)propyldimethylamine-N-oxides and dicephalic N,N-bis[3,3′-(dimethylamino)propyl]alkylamide di-N-oxides. Their antiradical properties were tested against stable radicals using electron paramagnetic resonance (EPR) and UV-vis spectroscopy. The experimental investigation was supported by theoretical density functional theory (DFT) and ab initio modeling of the X–H bonds dissociation enthalpies, ionization potentials, and Gibbs free energies for radical scavenging reactions. The evaluation was supplemented with a study of biological activity. We found that the mono- and di-N-oxides are capable of scavenging reactive radicals; however, the dicephalic surfactants are more efficient than their linear analogues.
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Affiliation(s)
- Agnieszka Lewińska
- Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, 50-383 Wroclaw, Poland
- Correspondence: (A.L.); (M.W.)
| | - Julita Kulbacka
- Department of Molecular and Cellular Biology, Faculty of Pharmacy, Wroclaw Medical University, Borowska 211A, 50-367 Wroclaw, Poland;
| | - Marta Domżał-Kędzia
- Department of Biotransformation, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383 Wroclaw, Poland;
| | - Maciej Witwicki
- Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, 50-383 Wroclaw, Poland
- Correspondence: (A.L.); (M.W.)
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25
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Oberdorf K, Hanft A, Ramler J, Krummenacher I, Bickelhaupt FM, Poater J, Lichtenberg C. Bismutamide als einfache Vermittler hochselektiver Pn−Pn‐Radikal‐Kupplungsreaktionen (Pn=N, P, As). Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202015514] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Kai Oberdorf
- Institut für Anorganische Chemie Julius-Maximilians-Universität, Würzburg Am Hubland 97074 Würzburg Deutschland
| | - Anna Hanft
- Institut für Anorganische Chemie Julius-Maximilians-Universität, Würzburg Am Hubland 97074 Würzburg Deutschland
| | - Jacqueline Ramler
- Institut für Anorganische Chemie Julius-Maximilians-Universität, Würzburg Am Hubland 97074 Würzburg Deutschland
| | - Ivo Krummenacher
- Institut für Anorganische Chemie Julius-Maximilians-Universität, Würzburg Am Hubland 97074 Würzburg Deutschland
| | - F. Matthias Bickelhaupt
- Institut für Theoretische Chemie, ACMM Vrije Universiteit Amsterdam Niederlande
- Institut für Moleküle und Materialien Radboud University Heyendaalseweg 135 6525 AJ Nijmegen Niederlande
| | - Jordi Poater
- Departament de Química Inorgànica i Orgànica & IQTCUB Universitat de Barcelona & ICREA Pg. Lluís Companys 23 08010 Barcelona Spanien
| | - Crispin Lichtenberg
- Institut für Anorganische Chemie Julius-Maximilians-Universität, Würzburg Am Hubland 97074 Würzburg Deutschland
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26
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Oberdorf K, Hanft A, Ramler J, Krummenacher I, Bickelhaupt FM, Poater J, Lichtenberg C. Bismuth Amides Mediate Facile and Highly Selective Pn-Pn Radical-Coupling Reactions (Pn=N, P, As). Angew Chem Int Ed Engl 2021; 60:6441-6445. [PMID: 33315293 PMCID: PMC7986226 DOI: 10.1002/anie.202015514] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Indexed: 12/14/2022]
Abstract
The controlled release of well-defined radical species under mild conditions for subsequent use in selective reactions is an important and challenging task in synthetic chemistry. We show here that simple bismuth amide species [Bi(NAr2 )3 ] readily release aminyl radicals [NAr2 ]. at ambient temperature in solution. These reactions yield the corresponding hydrazines, Ar2 N-NAr2 , as a result of highly selective N-N coupling. The exploitation of facile homolytic Bi-Pn bond cleavage for Pn-Pn bond formation was extended to higher homologues of the pnictogens (Pn=N-As): homoleptic bismuth amides mediate the highly selective dehydrocoupling of HPnR2 to give R2 Pn-PnR2 . Analyses by NMR and EPR spectroscopy, single-crystal X-ray diffraction, and DFT calculations reveal low Bi-N homolytic bond-dissociation energies, suggest radical coupling in the coordination sphere of bismuth, and reveal electronic and steric parameters as effective tools to control these reactions.
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Affiliation(s)
- Kai Oberdorf
- Department of Inorganic ChemistryJulius-Maximilians-Universität, WürzburgAm Hubland97074WürzburgGermany
| | - Anna Hanft
- Department of Inorganic ChemistryJulius-Maximilians-Universität, WürzburgAm Hubland97074WürzburgGermany
| | - Jacqueline Ramler
- Department of Inorganic ChemistryJulius-Maximilians-Universität, WürzburgAm Hubland97074WürzburgGermany
| | - Ivo Krummenacher
- Department of Inorganic ChemistryJulius-Maximilians-Universität, WürzburgAm Hubland97074WürzburgGermany
| | - F. Matthias Bickelhaupt
- Department of Theoretical Chemistry, ACMMVrije UniversiteitAmsterdamThe Netherlands
- Institute for Molecules and MaterialsRadboud UniversityHeyendaalseweg 1356525 AJNijmegenThe Netherlands
| | - Jordi Poater
- Departament de Química Inorgànica i Orgànica & IQTCUBUniversitat de Barcelona & ICREAPg. Lluís Companys 2308010BarcelonaSpain
| | - Crispin Lichtenberg
- Department of Inorganic ChemistryJulius-Maximilians-Universität, WürzburgAm Hubland97074WürzburgGermany
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