1
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Imex Aguirre Cardenas M, Siu TC, Pimentel AE, Hight MO, Shimono MG, Thai S, Carta V, Su TA. Installing Quaternary Germanium Centers in Sila-Diamondoid Cores via Skeletal Isomerization. J Am Chem Soc 2023; 145:20588-20594. [PMID: 37683101 DOI: 10.1021/jacs.3c07290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/10/2023]
Abstract
This manuscript describes skeletal isomerization strategies to install one to four quaternary germanium atoms in the sila-adamantane core, in a cluster analogy to precision germanium doping in silicon-germanium alloys. The first strategy embodies an inorganic variant of single-atom skeletal editing, where we use a sila-Wagner-Meerwein bond shift cascade to exchange a peripheral Ge atom with a core Si atom. We can install up to four Ge atoms at the quaternary diamondoid centers based on controlling the SixGey stoichiometry of our precursor. We find that bridgehead Ge centers can be selectively functionalized over bridgehead Si centers in SiGe adamantanes; we use this chemistry in conjunction with scanning tunneling microscopy break-junction (STM-BJ) measurements to show that Si8Ge2 adamantane wires give a 60% increase in single-molecule conductance compared with Si10 adamantanes. These studies describe the first quantum transport measurements in sila-diamondoid structures, and demonstrate how main-chain Ge doping can be used to increase electronic transmission in sila-diamondoid-based molecular wires.
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Affiliation(s)
- M Imex Aguirre Cardenas
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Timothy C Siu
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Ashley E Pimentel
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Matthew O Hight
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Miku G Shimono
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Shalivahana Thai
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Veronica Carta
- Department of Chemistry, University of California, Riverside, California 92521, United States
| | - Timothy A Su
- Department of Chemistry, University of California, Riverside, California 92521, United States
- Materials Science and Engineering Program, University of California, Riverside, California 92521, United States
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2
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Takeuchi T, Roy A, Ito H. Iterative Synthesis of Oligosilanes Using Methoxyphenyl- or Hydrogen-Substituted Silylboronates as Building Blocks: A General Synthetic Method for Complex Oligosilanes. J Am Chem Soc 2023. [PMID: 37436952 DOI: 10.1021/jacs.3c05385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Organosilanes have attracted the attention of researchers for more than 150 years due to their unique properties, and they have become indispensable industrial assets. However, many synthesized oligosilanes with multiple Si-Si bonds are relatively simple, i.e., they often only contain a single repeating unit. More laborious customized synthetic routes can lead to more complex oligosilanes, but compared to carbon-based molecules, their structural diversity remains limited. The development of effective and practical synthetic routes to complex oligosilanes that contain mixed substituents constitutes a long-standing challenge. Here, we describe an iterative synthesis of oligosilanes using methoxyphenyl- or hydrogen-substituted silylboronates, which were obtained via transition-metal-catalyzed Si-H borylation reactions. The first key reaction is a cross-Si-Si bond-forming reaction between chloro(oligo)silanes and silylboronates activated by MeLi. The second key reaction is the selective chlorination of the methoxyphenyl group or the hydrogen atom at the terminal of the oligosilanes. Iteration of these two key reactions enables the synthesis of various oligosilanes that are otherwise difficult to access. As a demonstration of the synthetic utility of this iterative synthetic approach, oligosilanes with different sequences were prepared by simply changing the order of the reaction of four different silicon units. Furthermore, a bespoke tree-shaped oligosilane is easily obtained via the present iterative synthesis. The solid-state structures of several of these oligosilanes were unequivocally determined using single-crystal X-ray diffraction analysis.
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Affiliation(s)
- Takumi Takeuchi
- Division of Applied Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
| | - Avijit Roy
- Division of Applied Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
| | - Hajime Ito
- Division of Applied Chemistry, Graduate School of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
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3
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Guan W, Lu L, Jiang Q, Gittens AF, Wang Y, Novaes LFT, Klausen RS, Lin S. An Electrochemical Strategy to Synthesize Disilanes and Oligosilanes from Chlorosilanes. Angew Chem Int Ed Engl 2023; 62:e202303592. [PMID: 37084266 PMCID: PMC10310474 DOI: 10.1002/anie.202303592] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 04/20/2023] [Accepted: 04/21/2023] [Indexed: 04/23/2023]
Abstract
Silanes are important compounds in industrial and synthetic chemistry. Here, we develop a general approach for the synthesis of disilanes as well as linear and cyclic oligosilanes via the reductive activation of readily available chlorosilanes. The efficient and selective generation of silyl anion intermediates, which are arduous to achieve by other means, allows for the synthesis of various novel oligosilanes by heterocoupling. In particular, this work presents a modular synthesis for a variety of functionalized cyclosilanes, which may give rise to materials with distinct properties from linear silanes but remain challenging synthetic targets. In comparison to the traditional Wurtz coupling, our method features milder conditions and improved chemoselectivity, broadening the functional groups that are compatible in oligosilane preparation. Computational studies support a mechanism whereby differential activation of sterically and electronically distinct chlorosilanes are achieved in an electrochemically driven radical-polar crossover mechanism.
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Affiliation(s)
- Weiyang Guan
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY-14853, USA
| | - Lingxiang Lu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY-14853, USA
| | - Qifeng Jiang
- Department of Chemistry, Johns Hopkins University, Baltimore, MD-21218, USA
| | | | - Yi Wang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY-14853, USA
| | - Luiz F T Novaes
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY-14853, USA
| | - Rebekka S Klausen
- Department of Chemistry, Johns Hopkins University, Baltimore, MD-21218, USA
| | - Song Lin
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY-14853, USA
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4
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Gittens AF, Jiang Q, Siegler MA, Klausen RS. Conjugation in Isomeric Cyclosilane Thioethers. Organometallics 2022. [DOI: 10.1021/acs.organomet.2c00501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- Alexandra F. Gittens
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St, Baltimore, Maryland 21218, United States
| | - Qifeng Jiang
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St, Baltimore, Maryland 21218, United States
| | - Maxime A. Siegler
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St, Baltimore, Maryland 21218, United States
| | - Rebekka S. Klausen
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St, Baltimore, Maryland 21218, United States
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5
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Garner MH, Koerstz M, Jensen JH, Solomon GC. Substituent Control of σ-Interference Effects in the Transmission of Saturated Molecules. ACS PHYSICAL CHEMISTRY AU 2022; 2:282-288. [PMID: 36855417 PMCID: PMC9955259 DOI: 10.1021/acsphyschemau.2c00016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The single-molecule conductance of saturated molecules can potentially be fully suppressed by destructive quantum interference in their σ-system. However, only few molecules with σ-interference have been identified, and the structure-property relationship remains to be elucidated. Here, we explore the role of substituents in modulating the electronic transmission of saturated molecules. In functionalized bicyclo[2.2.2]octanes, the transmission is suppressed by σ-interference when fluorine substituents are applied. For bicyclo[2.2.2]octasilane and -octagermanes, the transmission is suppressed when carbon-based substituents are used, and such molecules are likely to be highly insulating. For the carbon-based substituents, we find a strong correlation between the appropriate Hammett constants and the transmission. The substituent effect enables systematic optimization of the insulating properties of saturated molecular cores.
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Affiliation(s)
- Marc H. Garner
- Nano-Science
Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark,Department
of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Mads Koerstz
- Department
of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Jan H. Jensen
- Department
of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Gemma C. Solomon
- Nano-Science
Center, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark,Department
of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark,
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6
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Jiang Q, Gittens AF, Wong S, Siegler MA, Klausen RS. Highly selective addition of cyclosilanes to alkynes enabling new conjugated materials. Chem Sci 2022; 13:7587-7593. [PMID: 35872824 PMCID: PMC9241958 DOI: 10.1039/d2sc01690g] [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] [Received: 03/23/2022] [Accepted: 06/03/2022] [Indexed: 11/21/2022] Open
Abstract
Hybrid σ,π-conjugated cyclosilanes were synthesized via highly selective hydrosilylation and have shown great potentials as building blocks to construct novel conjugated polymers with control of tacticity.
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Affiliation(s)
- Qifeng Jiang
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St, Baltimore, MD 21218, USA
| | - Alexandra F. Gittens
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St, Baltimore, MD 21218, USA
| | - Sydnee Wong
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St, Baltimore, MD 21218, USA
| | - Maxime A. Siegler
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St, Baltimore, MD 21218, USA
| | - Rebekka S. Klausen
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St, Baltimore, MD 21218, USA
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7
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Ballestero‐Martínez E, Ferguson JT, Siegler MA, Klausen RS. Isolation of a Cyclopentasilane from Magnesium Reduction of a Linear Hexasilane. European J Org Chem 2021. [DOI: 10.1002/ejoc.202100768] [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)
- Ernesto Ballestero‐Martínez
- Department of Chemistry Johns Hopkins University 3400 N. Charles Street Baltimore MD 21218 USA
- Escuela de Química and Centro de Investigación en Ciencia e Ingeniería de Materiales Universidad de Costa Rica San José 11501-2060 Costa Rica
| | - John T. Ferguson
- Department of Chemistry Johns Hopkins University 3400 N. Charles Street Baltimore MD 21218 USA
| | - Maxime A. Siegler
- Department of Chemistry Johns Hopkins University 3400 N. Charles Street Baltimore MD 21218 USA
| | - Rebekka S. Klausen
- Department of Chemistry Johns Hopkins University 3400 N. Charles Street Baltimore MD 21218 USA
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8
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Jiang Q, Wong S, Klausen RS. Effect of polycyclosilane microstructure on thermal properties. Polym Chem 2021. [DOI: 10.1039/d1py00383f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Thermal characterization of polysilanes has focused on the influence of organic side chains, whereas little is understood about the influence of silane backbone microstructure on thermal stability, phase properties, and pyrolysis.
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Affiliation(s)
- Qifeng Jiang
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St, Baltimore, MD 21218, USA
| | - Sydnee Wong
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St, Baltimore, MD 21218, USA
| | - Rebekka S. Klausen
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St, Baltimore, MD 21218, USA
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9
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Lu L, Siu JC, Lai Y, Lin S. An Electroreductive Approach to Radical Silylation via the Activation of Strong Si-Cl Bond. J Am Chem Soc 2020; 142:21272-21278. [PMID: 33290654 DOI: 10.1021/jacs.0c10899] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The construction of C(sp3)-Si bonds is important in synthetic, medicinal, and materials chemistry. In this context, reactions mediated by silyl radicals have become increasingly attractive but methods for accessing these intermediates remain limited. We present a new strategy for silyl radical generation via electroreduction of readily available chlorosilanes. At highly biased potentials, electrochemistry grants access to silyl radicals through energetically uphill reductive cleavage of strong Si-Cl bonds. This strategy proved to be general in various alkene silylation reactions including disilylation, hydrosilylation, and allylic silylation under simple and transition-metal-free conditions.
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Affiliation(s)
- Lingxiang Lu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Juno C Siu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Yihuan Lai
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Song Lin
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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10
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Folster CP, Nguyen PN, Klausen RS. Reductive halocyclosilazane polymerization. Dalton Trans 2020; 49:16125-16132. [PMID: 31994564 DOI: 10.1039/c9dt04468j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthesis of a chloro-functionalized six-membered cyclosilazane (Si5N) is reported. Subsequent reductive polymerizations yielded low molecular weight polysilazanes. 1H and 29Si NMR characterization suggest the identity of the reducing metal influences the polysilazane structure. Optical characterization is consistent with extended σ-conjugation upon polymerization.
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Affiliation(s)
- Carlton P Folster
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles St, Baltimore, MD 21218, USA.
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11
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Ferguson JT, Jiang Q, Marro EA, Siegler MA, Klausen RS. Long-range coupling in cyclic silanes. Dalton Trans 2020; 49:14951-14961. [PMID: 33079122 DOI: 10.1039/d0dt03163a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the synthesis of a mixed methyl- and hydro-substituted cyclosilane (1) possessing cis/trans stereoisomerism. Each diastereomer of 1 possesses distinct symmetry elements (cis-1: Cs-symmetric; trans-1: C2-symmetric). Cyclosilane 1 is a model system to probe configuration- and conformation-dependent long-range proton-proton coupling. Extensive NMR spectroscopic characterization is reported, including one-dimensional 1H NMR and 29Si DEPT and INEPT+ spectra and two-dimensional 1H-29Si and 1H-1H correlated spectroscopy (HSQC, HMBC, COSY). On the basis of these experiments, molecular connectivity consistent with four-bond 1H-1H coupling is confirmed.
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Affiliation(s)
- John T Ferguson
- Deprtment of Chemistry, Johns Hopkins University, 3400 N. Charles St, Baltimore, MD 21218, USA.
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12
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Wiesner T, Leypold M, Steinmaurer A, Schnalzer D, Fischer RC, Torvisco A, Haas M. Synthesis of Stable Dianionic Cyclic Silenolates and Germenolates. Organometallics 2020; 39:2878-2887. [PMID: 32801424 PMCID: PMC7422643 DOI: 10.1021/acs.organomet.0c00385] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Indexed: 11/29/2022]
Abstract
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In this contribution a convenient
synthetic method to obtain the
previously unknown dianionic cyclic silenolates and germenolates is
described. These dianions 2a,b and 4a,b are easily accessible via a one-pot synthetic protocol in high yields. Their structural properties
were analyzed by a combination of NMR, single-crystal X-ray crystallography,
and DFT quantum mechanical calculations. Moreover, the reactivity
of 2a,b and 4a,b with selected examples of electrophiles was investigated. 2a and 4a were reacted with ClSiiPr3 to give new examples of polysilanes and polygermanes
with exocyclic double bonds. The reaction of 2b with
ClSiMe2SiMe2Cl led to the formation of the acyl
bicyclo[2.2.2]octasilane 6. Moreover, the reaction of 2a,b and 4a,b with
MeI, as an example of a carbon-centered electrophile, led to selective
alkylation reactions at the negatively charged silicon and germanium
atoms. The corresponding methylated structures 9a,b and 10a,b were formed in nearly
quantitative yields. The competitive reactivity of the silyl and silenolate
anion toward 1 equiv of ClSiMe3 showed that the outcome
of the reaction was strongly influenced by the substituent at the
carbonyl moiety. 2a reacted with 1 equiv of ClSiMe3 to give the corresponding cyclic silenolate S1a, which demonstrated that
the silyl anion is more nucleophilic than the silenolate with attached
aromatic groups. 2b, on the other hand, reacted with
1 equiv of ClSiMe3 to give the bicyclic compound 11via an intramolecular sila-Peterson alkenation
reaction. These findings clearly showed that the alkyl-substituted
silenolate is more nucleophilic than the silyl anion. This paper demonstrates
that 2a,b and 4a,b have the potential to be used as unique building blocks for complex
polysilane and polygermane frameworks.
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Affiliation(s)
- Tanja Wiesner
- Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
| | - Mario Leypold
- Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
| | - Anja Steinmaurer
- Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
| | - Dominik Schnalzer
- Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
| | - Roland C Fischer
- Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
| | - Ana Torvisco
- Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
| | - Michael Haas
- Institute of Inorganic Chemistry, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria
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