1
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Kelling L, Eßer J, Knyszek D, Gessner VH. Carbon-Based Weakly Coordinating Anions: Molecular Design, Synthesis and Applications. Angew Chem Int Ed Engl 2024:e202405936. [PMID: 38877830 DOI: 10.1002/anie.202405936] [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: 03/27/2024] [Revised: 06/07/2024] [Accepted: 06/10/2024] [Indexed: 06/16/2024]
Abstract
Although carbanions, which are usually regarded as reactive species and powerful metalation reagents, can be stabilized through choice of the substitution pattern, they have rarely been considered for the design of weakly coordinating anions (WCA). Here, we report on an evaluation of the potential of a series of differently substituted carbanions to serve as WCA by computational methods. This led us to the synthesis of the water- and air-stable allyl anion 1 with triflyl and 3,5-bis(trifluoromethyl)phenyl (ArF) moieties, which can be isolated in high yields even on a gram-scale. Single crystal X-ray crystallography and NMR studies confirmed the weak coordination ability of the anion by showing negligible or only weak interactions with different cations. This property enabled the application of 1 in the stabilization of reactive group 14 and 15 cations. In addition to the crystallization of a phosphenium cation, the first all-carbon salt with a non-aromatic carbanion is reported, which revealed to be a convenient reagent for hydride abstraction such as from silanes. Overall, this work demonstrates the so far untapped potential of carbanions as WCA, that are accessible with a variety of different cations for various applications.
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Affiliation(s)
- Leif Kelling
- Inorganic Chemistry II, Ruhr-University Bochum, Universitätsstraße 150, 44801, Bochum, Germany
| | - Julian Eßer
- Inorganic Chemistry II, Ruhr-University Bochum, Universitätsstraße 150, 44801, Bochum, Germany
| | - Daniel Knyszek
- Inorganic Chemistry II, Ruhr-University Bochum, Universitätsstraße 150, 44801, Bochum, Germany
| | - Viktoria H Gessner
- Inorganic Chemistry II, Ruhr-University Bochum, Universitätsstraße 150, 44801, Bochum, Germany
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2
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Witte JF, Wasternack J, Wei S, Schalley CA, Paulus B. The Interplay of Weakly Coordinating Anions and the Mechanical Bond: A Systematic Study of the Explicit Influence of Counterions on the Properties of (Pseudo)rotaxanes. Molecules 2023; 28:molecules28073077. [PMID: 37049840 PMCID: PMC10096450 DOI: 10.3390/molecules28073077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/17/2023] [Accepted: 03/27/2023] [Indexed: 04/03/2023] Open
Abstract
Weakly coordinating anions (WCAs) have attracted much attention in recent years due to their ability to stabilise highly reactive cations. It may well be argued, however, that a profound understanding of what truly defines a WCA is still lacking, and systematic studies to unravel counterion effects are scarce. In this work, we investigate a supramolecular pseudorotaxane formation reaction, subject to a selection of anions, ranging from strongly to weakly coordinating, which not only aids in fostering our knowledge about anion coordination properties, but also provides valuable theoretical insight into the nature of the mechanical bond. We employ state-of-the-art DFT-based methods and tools, combined with isothermal calorimetry and 1H NMR experiments, to compute anion-dependent Gibbs free association energies ΔGa, as well as to evaluate intermolecular interactions. We find correlations between ΔGa and the anions’ solvation energies, which are exploited to calculate physico-chemical reaction parameters in the context of coordinating anions. Furthermore, we show that the binding situation within the (pseudo)rotaxanes can be mostly understood by straight-forward electrostatic considerations. However, quantum-chemical effects such as dispersion and charge-transfer interactions become more and more relevant when WCAs are employed.
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Affiliation(s)
- J. Felix Witte
- Institut für Chemie und Biochemie, Physikalische und Theoretische Chemie, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany
- Correspondence: (J.F.W.); (B.P.)
| | - Janos Wasternack
- Institut für Chemie und Biochemie, Organische Chemie, Freie Universität Berlin, Arnimallee 20, 14195 Berlin, Germany
| | - Shenquan Wei
- Institut für Chemie und Biochemie, Physikalische und Theoretische Chemie, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany
| | - Christoph A. Schalley
- Institut für Chemie und Biochemie, Organische Chemie, Freie Universität Berlin, Arnimallee 20, 14195 Berlin, Germany
| | - Beate Paulus
- Institut für Chemie und Biochemie, Physikalische und Theoretische Chemie, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, Germany
- Correspondence: (J.F.W.); (B.P.)
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3
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Zapf L, Riethmann M, Föhrenbacher SA, Finze M, Radius U. An easy-to-perform evaluation of steric properties of Lewis acids. Chem Sci 2023; 14:2275-2288. [PMID: 36873848 PMCID: PMC9977453 DOI: 10.1039/d3sc00037k] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 02/04/2023] [Indexed: 02/08/2023] Open
Abstract
Steric and electronic effects play a very important role in chemistry, as these effects influence the shape and reactivity of molecules. Herein, an easy-to-perform approach to assess and quantify steric properties of Lewis acids with differently substituted Lewis acidic centers is reported. This model applies the concept of the percent buried volume (%V Bur) to fluoride adducts of Lewis acids, as many fluoride adducts are crystallographically characterized and are frequently calculated to judge fluoride ion affinities (FIAs). Thus, data such as cartesian coordinates are often easily available. A list of 240 Lewis acids together with topographic steric maps and cartesian coordinates of an oriented molecule suitable for the SambVca 2.1 web application is provided, together with different FIA values taken from the literature. Diagrams of %V Bur as a scale for steric demand vs. FIA as a scale for Lewis acidity provide valuable information about stereo-electronic properties of Lewis acids and an excellent evaluation of steric and electronic features of the Lewis acid under consideration. Furthermore, a novel LAB-Rep model (Lewis acid/base repulsion model) is introduced, which judges steric repulsion in Lewis acid/base pairs and helps to predict if an arbitrary pair of Lewis acid and Lewis base can form an adduct with respect to their steric properties. The reliability of this model was evaluated in four selected case studies, which demonstrate the versatility of this model. For this purpose, a user-friendly Excel spreadsheet was developed and is provided in the ESI, which works with listed buried volumes of Lewis acids %V Bur_LA and of Lewis bases %V Bur_LB, and no results from experimental crystal structures or quantum chemical calculations are necessary to evaluate steric repulsion in these Lewis acid/base pairs.
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Affiliation(s)
- Ludwig Zapf
- Institute of Inorganic Chemistry, Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany https://www.ak-radius.de https://go.uniwue.de/finze-group.,Institute for Sustainable Chemistry & Catalysis with Boron (ICB), Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Melanie Riethmann
- Institute of Inorganic Chemistry, Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany https://www.ak-radius.de https://go.uniwue.de/finze-group.,Institute for Sustainable Chemistry & Catalysis with Boron (ICB), Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Steffen A Föhrenbacher
- Institute of Inorganic Chemistry, Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany https://www.ak-radius.de https://go.uniwue.de/finze-group
| | - Maik Finze
- Institute of Inorganic Chemistry, Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany https://www.ak-radius.de https://go.uniwue.de/finze-group.,Institute for Sustainable Chemistry & Catalysis with Boron (ICB), Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany
| | - Udo Radius
- Institute of Inorganic Chemistry, Julius-Maximilians-Universität Würzburg Am Hubland 97074 Würzburg Germany https://www.ak-radius.de https://go.uniwue.de/finze-group
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4
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Porath S, Keßler M, Neumann B, Stammler HG, Hoge B. Synthesis and Characterization of Tetrakis(pentafluoroethyl)indate Salts. Chemistry 2023; 29:e202203278. [PMID: 36610041 DOI: 10.1002/chem.202203278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 01/04/2023] [Accepted: 01/05/2023] [Indexed: 01/09/2023]
Abstract
In the rising field of organoindium chemistry little is known about the perfluoroorganyl-substituted indium compounds. The increasing use of indium reagents is explained by their high stability and tolerance towards water and functional groups. Here we report on the synthesis of the novel tetrakis(pentafluoroethyl)indate, [In(C2 F5 )4 ]- , and its characterization in salts with the cations [Li(thf)3 ]+ , Cs+ , [PPh4 ]+ and [H14 O6 ]2+ (thf=tetrahydrofuran). To the best of our knowledge, these salts constitute the first perfluoroalkylindates and, in general, the first isolated perfluoroalkylindium compounds which are fully characterized by NMR spectroscopy, mass spectrometry, elemental analysis and X-ray diffraction analysis.
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Affiliation(s)
- Sven Porath
- Universität Bielefeld, Fakultät für Chemie, Centrum für Molekulare Materialien, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Mira Keßler
- Universität Bielefeld, Fakultät für Chemie, Centrum für Molekulare Materialien, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Beate Neumann
- Universität Bielefeld, Fakultät für Chemie, Centrum für Molekulare Materialien, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Hans-Georg Stammler
- Universität Bielefeld, Fakultät für Chemie, Centrum für Molekulare Materialien, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Berthold Hoge
- Universität Bielefeld, Fakultät für Chemie, Centrum für Molekulare Materialien, Universitätsstraße 25, 33615, Bielefeld, Germany
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5
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Tiessen N, Schwarze N, Keßler M, Neumann B, Stammler HG, Hoge B. Tris(pentafluoroethyl)silanol Derivatives and the Lewis Amphoteric Tris(pentafluoroethyl)silanolate Anion, [Si(C 2 F 5 ) 3 O] . Chemistry 2021; 27:11041-11044. [PMID: 34061416 PMCID: PMC8453507 DOI: 10.1002/chem.202101845] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Indexed: 02/02/2023]
Abstract
While alkyl‐substituted siloxanes are widely known, virtually nothing is known about perfluoroalkyl siloxanes and their congener species, the silanols and silanolates. We recently reported on the tris(pentafluoroethyl)silanide ion, [Si(C2F5)3]−, which features Lewis amphoteric character deriving from the pentafluoroethyl substituents and their strong electron‐withdrawing properties. Transferring this knowledge, we investigated the Lewis amphoteric behavior of the tris(pentafluoroethyl)silanolate, [Si(C2F5)3O]−. In order to examine such Lewis amphoteric behavior, we first developed a strategy for the synthesis of the corresponding silanol Si(C2F5)3OH, which readily condenses at room temperature to the hexakis(pentafluoroethyl)disiloxane, (C2F5)3SiOSi(C2F5)3. Deprotonation of Si(C2F5)3OH employing a sterically demanding phosphazene base allows the characterization of the first example of a dimeric triorganosilanolate: the dianionic hexakis(pentafluoroethyl)disilanolate, [{Si(C2F5)3O}2]2−, implies Lewis amphoteric character of the monomeric [Si(C2F5)3O]− anion.
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Affiliation(s)
- Natalia Tiessen
- Universität Bielefeld, Fakultät für Chemie, Centrum für Molekulare Materialien, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Nico Schwarze
- Universität Bielefeld, Fakultät für Chemie, Centrum für Molekulare Materialien, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Mira Keßler
- Universität Bielefeld, Fakultät für Chemie, Centrum für Molekulare Materialien, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Beate Neumann
- Universität Bielefeld, Fakultät für Chemie, Centrum für Molekulare Materialien, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Hans-Georg Stammler
- Universität Bielefeld, Fakultät für Chemie, Centrum für Molekulare Materialien, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Berthold Hoge
- Universität Bielefeld, Fakultät für Chemie, Centrum für Molekulare Materialien, Universitätsstraße 25, 33615, Bielefeld, Germany
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6
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Tiessen N, Keßler M, Neumann B, Stammler H, Hoge B. Nachweis des Lewis‐amphoteren Charakters von Tris(pentafluorethyl)silanid, [Si(C
2
F
5
)
3
]
−. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202016455] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Natalia Tiessen
- Universität Bielefeld Fakultät für Chemie Centrum für Molekulare Materialien Universitätsstraße 25 33615 Bielefeld Deutschland
| | - Mira Keßler
- Universität Bielefeld Fakultät für Chemie Centrum für Molekulare Materialien Universitätsstraße 25 33615 Bielefeld Deutschland
| | - Beate Neumann
- Universität Bielefeld Fakultät für Chemie Centrum für Molekulare Materialien Universitätsstraße 25 33615 Bielefeld Deutschland
| | - Hans‐Georg Stammler
- Universität Bielefeld Fakultät für Chemie Centrum für Molekulare Materialien Universitätsstraße 25 33615 Bielefeld Deutschland
| | - Berthold Hoge
- Universität Bielefeld Fakultät für Chemie Centrum für Molekulare Materialien Universitätsstraße 25 33615 Bielefeld Deutschland
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7
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Tiessen N, Keßler M, Neumann B, Stammler H, Hoge B. Evidence of the Lewis-Amphoteric Character of Tris(pentafluoroethyl)silanide, [Si(C 2 F 5 ) 3 ] . Angew Chem Int Ed Engl 2021; 60:12124-12131. [PMID: 33617080 PMCID: PMC8252080 DOI: 10.1002/anie.202016455] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 02/09/2021] [Indexed: 12/16/2022]
Abstract
According to a first view on the geometrical and electronic structure of the tris(pentafluoroethyl)silanide, this anion appears as a Lewis base. Quantum chemical calculations on perfluoroalkylated silanides show significantly lower HOMO and LUMO energy levels in comparison to their non-fluorinated counterparts, which implies reduced Lewis basicity and increased Lewis acidity of the [Si(C2 F5 )3 ]- ion. With these findings and a HOMO-LUMO gap of 4.80 eV similar to N-heterocyclic silylenes (NHSis), perfluoroalkyl silanides are predestined to exhibit Lewis-amphoteric character similar to silylenes. Deprotonation of Si(C2 F5 )3 H with sterically demanding phosphazene bases afforded thermally stable phosphazenium salts of the [Si(C2 F5 )3 ]- anion, which add to benzaldehyde, benzophenone, CS2 , and CO2 in various manners. This behavior also mirrors the reactivity of silylenes towards ketones as well as heterocumulenes and is rationalized by Lewis amphotericity being inherent in these silanides.
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Affiliation(s)
- Natalia Tiessen
- Universität BielefeldFakultät für ChemieCentrum für Molekulare MaterialienUniversitätsstrasse 2533615BielefeldGermany
| | - Mira Keßler
- Universität BielefeldFakultät für ChemieCentrum für Molekulare MaterialienUniversitätsstrasse 2533615BielefeldGermany
| | - Beate Neumann
- Universität BielefeldFakultät für ChemieCentrum für Molekulare MaterialienUniversitätsstrasse 2533615BielefeldGermany
| | - Hans‐Georg Stammler
- Universität BielefeldFakultät für ChemieCentrum für Molekulare MaterialienUniversitätsstrasse 2533615BielefeldGermany
| | - Berthold Hoge
- Universität BielefeldFakultät für ChemieCentrum für Molekulare MaterialienUniversitätsstrasse 2533615BielefeldGermany
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8
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Weitkamp RF, Neumann B, Stammler H, Hoge B. The Influence of Weakly Coordinating Cations on the O-H⋅⋅⋅O - Hydrogen Bond of Silanol-Silanolate Anions. Chemistry 2021; 27:915-920. [PMID: 33180359 PMCID: PMC7839788 DOI: 10.1002/chem.202004236] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 11/06/2020] [Indexed: 11/21/2022]
Abstract
The reaction of a saline phosphazenium hydroxide hydrate with siloxanes led to a novel kind of silanol-silanolate anions. The weakly coordinating behavior of the cation renders the formation of silanol-silanolate hydrogen bonds possible, which otherwise suffer from detrimental silanolate-oxygen cation interactions. We investigated the influence of various weakly coordinating cations on silanol-silanolate motifs, particularly with regard to different cation sizes. While large cations favor the formation of intramolecular hydrogen bonds resulting in cyclic structures, the less bulky tetramethyl ammonium cation encourages the formation of polyanionic silanol-silanolate chains in the solid state.
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Affiliation(s)
- Robin F. Weitkamp
- Centrum für Molekulare MaterialienFakultät für ChemieUniversität BielefeldUniversitätsstraße 2533615BielefeldGermany
| | - Beate Neumann
- Centrum für Molekulare MaterialienFakultät für ChemieUniversität BielefeldUniversitätsstraße 2533615BielefeldGermany
| | - Hans‐Georg Stammler
- Centrum für Molekulare MaterialienFakultät für ChemieUniversität BielefeldUniversitätsstraße 2533615BielefeldGermany
| | - Berthold Hoge
- Centrum für Molekulare MaterialienFakultät für ChemieUniversität BielefeldUniversitätsstraße 2533615BielefeldGermany
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9
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Bischoff LA, Riefer J, Wirthensohn R, Bischof T, Bertermann R, Ignat'ev NV, Finze M. Pentafluoroethylaluminates: A Combined Synthetic, Spectroscopic, and Structural Study. Chemistry 2020; 26:13615-13620. [PMID: 32167200 PMCID: PMC7689865 DOI: 10.1002/chem.202000667] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Indexed: 01/24/2023]
Abstract
Salts of the tetrakis(pentafluoroethyl)aluminate anion [Al(C2 F5 )4 ]- were obtained from AlCl3 and LiC2 F5 . They were isolated with different counter-cations and characterized by NMR and vibrational spectroscopy and mass spectrometry. Degradation of the [Al(C2 F5 )4 ]- ion was found to proceed via 1,2-fluorine shifts and stepwise loss of CF(CF3 ) under formation of [(C2 F5 )4-n AlFn ]- (n=1-4) as assessed by NMR spectroscopy and mass spectrometry and supported by results of DFT calculations. In addition, the [(C2 F5 )AlF3 ]- ion was structurally characterized.
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Affiliation(s)
- Lisa A. Bischoff
- Institut für nachhaltige Chemie & Katalyse mit Bor (ICB)Institut für Anorganische ChemieJulius- Maximimilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Jarno Riefer
- Institut für nachhaltige Chemie & Katalyse mit Bor (ICB)Institut für Anorganische ChemieJulius- Maximimilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Raphael Wirthensohn
- Institut für nachhaltige Chemie & Katalyse mit Bor (ICB)Institut für Anorganische ChemieJulius- Maximimilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Tobias Bischof
- Institut für nachhaltige Chemie & Katalyse mit Bor (ICB)Institut für Anorganische ChemieJulius- Maximimilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Rüdiger Bertermann
- Institut für nachhaltige Chemie & Katalyse mit Bor (ICB)Institut für Anorganische ChemieJulius- Maximimilians-Universität WürzburgAm Hubland97074WürzburgGermany
| | - Nikolai V. Ignat'ev
- Institut für nachhaltige Chemie & Katalyse mit Bor (ICB)Institut für Anorganische ChemieJulius- Maximimilians-Universität WürzburgAm Hubland97074WürzburgGermany
- ConsultantMerck KGaA64293DarmstadtGermany
| | - Maik Finze
- Institut für nachhaltige Chemie & Katalyse mit Bor (ICB)Institut für Anorganische ChemieJulius- Maximimilians-Universität WürzburgAm Hubland97074WürzburgGermany
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