TY  - JOUR
A1  - Mukhopadhyay, Deb Pratim
A1  - Schleier, Domenik
A1  - Wirsing, Sara
A1  - Ramler, Jaqueline
A1  - Kaiser, Dustin
A1  - Reusch, Engelbert
A1  - Hemberger, Patrick
A1  - Preitschopf, Tobias
A1  - Krummenacher, Ivo
A1  - Engels, Bernd
A1  - Fischer, Ingo
A1  - Lichtenberg, Crispin
T1  - Methylbismuth: an organometallic bismuthinidene biradical
JF  - Chemical Science
N2  - We report the generation, spectroscopic characterization, and computational analysis of the first free (non-stabilized) organometallic bismuthinidene, BiMe. The title compound was generated in situ from BiMe\(_3\) by controlled homolytic Bi–C bond cleavage in the gas phase. Its electronic structure was characterized by a combination of photoion mass-selected threshold photoelectron spectroscopy and DFT as well as multi-reference computations. A triplet ground state was identified and an ionization energy (IE) of 7.88 eV was experimentally determined. Methyl abstraction from BiMe\(_3\) to give [BiMe(_2\)]• is a key step in the generation of BiMe. We reaveal a bond dissociation energy of 210 ± 7 kJ mol\(^{−1}\), which is substantially higher than the previously accepted value. Nevertheless, the homolytic cleavage of Me–BiMe\(_2\) bonds could be achieved at moderate temperatures (60–120 °C) in the condensed phase, suggesting that [BiMe\(_2\)]• and BiMe are accessible as reactive intermediates under these conditions.
KW  - methylbismuth
KW  - Photoelektronenspektroskopie
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-251657
UR  - https://pubs.rsc.org/en/content/articlelanding/2020/SC/D0SC02410D
VL  - 11
IS  - 29
ER  - 
TY  - JOUR
A1  - Ramler, Jacqueline
A1  - Krummenacher, Ivo
A1  - Lichtenberg, Crispin
T1  - Well‐Defined, Molecular Bismuth Compounds: Catalysts in Photochemically Induced Radical Dehydrocoupling Reactions
JF  - Chemistry – A European Journal
N2  - A series of diorgano(bismuth)chalcogenides, [Bi(di‐aryl)EPh], has been synthesised and fully characterised (E=S, Se, Te). These molecular bismuth complexes have been exploited in homogeneous photochemically‐induced radical catalysis, using the coupling of silanes with TEMPO as a model reaction (TEMPO=(tetramethyl‐piperidin‐1‐yl)‐oxyl). Their catalytic properties are complementary or superior to those of known catalysts for these coupling reactions. Catalytically competent intermediates of the reaction have been identified. Applied analytical techniques include NMR, UV/Vis, and EPR spectroscopy, mass spectrometry, single‐crystal X‐ray diffraction analysis, and (TD)‐DFT calculations.
KW  - bismuth
KW  - chalcogens
KW  - dehydrocoupling
KW  - photocatalysis
KW  - radical reactions
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-224577
VL  - 26
IS  - 64
SP  - 14551
EP  - 14555
ER  - 
TY  - JOUR
A1  - Ramler, Jacqueline
A1  - Lichtenberg, Crispin
T1  - Molecular Bismuth Cations: Assessment of Soft Lewis Acidity
JF  - Chemistry – A European Journal
N2  - Three‐coordinate cationic bismuth compounds [Bi(diaryl)(EPMe\(_{3}\))][SbF\(_{6}\)] have been isolated and fully characterized (diaryl=[(C\(_{6}\)H\(_{4}\))\(_{2}\)C\(_{2}\)H\(_{1}\)]\(^{2-}\), E=S, Se). They represent rare examples of molecular complexes with Bi⋅⋅⋅EPR\(_{3}\) interactions (R=monoanionic substituent). The \(^{31}\)P NMR chemical shift of EPMe3 has been found to be sensitive to the formation of LA⋅⋅⋅EPMe\(_{3}\) Lewis acid/base interactions (LA=Lewis acid). This corresponds to a modification of the Gutmann–Beckett method and reveals information about the hardness/softness of the Lewis acid under investigation. A series of organobismuth compounds, bismuth halides, and cationic bismuth species have been investigated with this approach and compared to traditional group 13 and cationic group 14 Lewis acids. Especially cationic bismuth species have been shown to be potent soft Lewis acids that may prefer Lewis pair formation with a soft (S/Se‐based) rather than a hard (O/N‐based) donor. Analytical techniques applied in this work include (heteronuclear) NMR spectroscopy, single‐crystal X‐ray diffraction analysis, and DFT calculations.
KW  - bismuth
KW  - bonding analysis
KW  - cationic species
KW  - HSAB principle
KW  - Lewis acids
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225808
VL  - 26
IS  - 45
SP  - 10250
EP  - 10258
ER  - 
TY  - JOUR
A1  - Lichtenberg, Crispin
T1  - Main‐Group Metal Complexes in Selective Bond Formations Through Radical Pathways
JF  - Chemistry – A European Journal
N2  - Recent years have witnessed remarkable advances in radical reactions involving main‐group metal complexes. This includes the isolation and detailed characterization of main‐group metal radical compounds, but also the generation of highly reactive persistent or transient radical species. A rich arsenal of methods has been established that allows control over and exploitation of their unusual reactivity patterns. Thus, main‐group metal compounds have entered the field of selective bond formations in controlled radical reactions. Transformations that used to be the domain of late transition‐metal compounds have been realized, and unusual selectivities, high activities, as well as remarkable functional‐group tolerances have been reported. Recent findings demonstrate the potential of main‐group metal compounds to become standard tools of synthetic chemistry, catalysis, and materials science, when operating through radical pathways.
KW  - bond formation
KW  - catalysis
KW  - main-group metals
KW  - organic and inorganic synthesis
KW  - radicals
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-214758
VL  - 26
IS  - 44
SP  - 9674
EP  - 9687
ER  - 
TY  - JOUR
A1  - Hanft, Anna
A1  - Lichtenberg, Crispin
T1  - Dimerization of 2-[(2-((2-aminophenyl)thio)phenyl)amino]-cyclohepta-2,4,6-trien-1-one through hydrogen bonding, C\(_{19}\)H\(_{16}\)N\(_2\)OS
JF  - Zeitschrift für Kristallographie - New Crystal Structures
N2  - C\(_{19}\)H\(_{16}\)N\(_2\)OS, triclinic, P (1) over bar (no. 2), a= 8.1510(3) angstrom, b = 8.8021(3) angstrom, c =11.3953(5) angstrom, alpha =72.546(2)degrees, beta=84.568(2)degrees, gamma =80.760(2)degrees, V =768.86(5) angstrom(3), Z =2, R\(_{gt}\)(F) = 0.0491, WR\(_{ref}\)(F-2) = 0.1494, T =100 K.
KW  - crystal structure
KW  - complexes
KW  - ligands
KW  - tropocoronands
KW  - mononuclear
KW  - chemistry
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-229482
VL  - 235
IS  - 4
ER  -