TY  - JOUR
A1  - Huang, Mingming
A1  - Hu, Jiefeng
A1  - Krummenacher, Ivo
A1  - Friedrich, Alexandra
A1  - Braunschweig, Holger
A1  - Westcott, Stephen A.
A1  - Radius, Udo
A1  - Marder, Todd B.
T1  - Base-Mediated Radical Borylation of Alkyl Sulfones
JF  - Chemistry—A European Journal
N2  - A practical and direct method was developed for the production of versatile alkyl boronate esters via transition metal-free borylation of primary and secondary alkyl sulfones. The key to the success of the strategy is the use of bis(neopentyl glycolato) diboron (B\(_{2}\)neop\(_{2}\)), with a stoichiometric amount of base as a promoter. The practicality and industrial potential of this protocol are highlighted by its wide functional group tolerance, the late-stage modification of complex compounds, no need for further transesterification, and operational simplicity. Radical clock, radical trap experiments, and EPR studies were conducted which show that the borylation process involves radical intermediates.
KW  - boron
KW  - boronate
KW  - boronic acid
KW  - metal-free
KW  - radical
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-257281
VL  - 28
IS  - 3
ER  - 
TY  - JOUR
A1  - Lu, Wei
A1  - Jayaraman, Arumugam
A1  - Fantuzzi, Felipe
A1  - Dewhurst, Rian D.
A1  - Härterich, Marcel
A1  - Dietz, Maximilian
A1  - Hagspiel, Stephan
A1  - Krummenbacher, Ivo
A1  - Hammond, Kai
A1  - Cui, Jingjing
A1  - Braunschweig, Holger
T1  - An unsymmetrical, cyclic diborene based on a chelating CAAC ligand and its small-molecule activation and rearrangement chemistry
JF  - Angewandte Chemie International Edition
N2  - A one-pot synthesis of a CAAC-stabilized, unsymmetrical, cyclic diborene was achieved via consecutive two-electron reduction steps from an adduct of CAAC and B\(_2\)Br\(_4\)(SMe\(_2\))\(_2\). Theoretical studies revealed that this diborene has a considerably smaller HOMO–LUMO gap than those of reported NHC- and phosphine-supported diborenes. Complexation of the diborene with [AuCl(PCy\(_3\))] afforded two diborene–Au\(^I\) π complexes, while reaction with DurBH\(_2\), P\(_4\) and a terminal acetylene led to the cleavage of B−H, P−P, and C−C π bonds, respectively. Thermal rearrangement of the diborene gave an electron-rich cyclic alkylideneborane, which readily coordinated to Ag\(^I\) via its B=C double bond.
KW  - inorganic chemistry
KW  - thermal rearrangement
KW  - alkylideneborane
KW  - carbene
KW  - diborene
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256576
VL  - 61
IS  - 3
ER  - 
TY  - JOUR
A1  - Gerlach, Marius
A1  - Monninger, Sophie
A1  - Schleier, Domenik
A1  - Hemberger, Patrick
A1  - Goettel, James T.
A1  - Braunschweig, Holger
A1  - Fischer, Ingo
T1  - Photoelectron Photoion Coincidence Spectroscopy of NCl\(_{3}\) and NCl\(_{2}\)
JF  - ChemPhysChem
N2  - We investigate NCl\(_{3}\) and the NCl\(_{2}\) radical by photoelectron-photoion coincidence spectroscopy using synchrotron radiation. The mass selected threshold photoelectron spectrum (ms-TPES) of NCl\(_{3}\) is broad and unstructured due to the large geometry change. An ionization energy of 9.7±0.1 eV is estimated from the spectrum and supported by computations. NCl2 is generated by photolysis at 213 nm from NCl\(_{3}\) and its ms-TPES shows an extended vibrational progression with a 90 meV spacing that is assigned to the symmetric N−Cl stretching mode in the cation. An adiabatic ionization energy of 9.94 ± 0.02 eV is determined.
KW  - radicals
KW  - photoelectron spectroscopy
KW  - synchrotron radiation
KW  - nitrogen trichloride
KW  - photolysis
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-257322
VL  - 22
IS  - 21
ER  - 
TY  - JOUR
A1  - Hagspiel, Stephan
A1  - Arrowsmith, Merle
A1  - Fantuzzi, Felipe
A1  - Vargas, Alfredo
A1  - Rempel, Anna
A1  - Hermann, Alexander
A1  - Brückner, Tobias
A1  - Braunschweig, Holger
T1  - Highly colored boron-doped thiazolothiazoles from the reductive dimerization of boron isothiocyanates
JF  - Angewandte Chemie International Edition
N2  - Reduction of (CAAC)BBr\(_2\)(NCS) (CAAC=cyclic alkyl(amino)carbene) in the presence of a Lewis base L yields tricoordinate (CAAC)LB(NCS) borylenes which undergo reversible E/Z-isomerization. The same reduction in the absence of L yields deep blue, bis(CAAC)-stabilized, boron-doped, aromatic thiazolothiazoles resulting from the dimerization of dicoordinate (CAAC)B(NCS) borylene intermediates.
KW  - inorganic chemistry
KW  - aromaticity
KW  - reduction
KW  - fused thiazaboroles
KW  - DFT
KW  - borylenes
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256432
VL  - 60
IS  - 12
ER  - 
TY  - JOUR
A1  - Riensch, Nicolas Alexander
A1  - Swoboda, Lukas
A1  - Lik, Artur
A1  - Krummenacher, Ivo
A1  - Braunschweig, Holger
A1  - Helten, Holger
T1  - Conjugated Bis(triarylboranes) with Disconnected Conjugation
JF  - Zeitschrift für anorganische und allgemeine Chemie
N2  - A series of methylene-bridged bis(triarylboranes) has been synthesized via two complementary routes using metal-free catalytic Si/B exchange condensation under mild conditions. The title compounds comprise two borane moieties that show effective internal π-conjugation involving the respective boron centers and the adjacent hetaryl groups. Conjugation between both borane units, however, is disrupted by the aliphatic linker. Cyclic voltammetry revealed minimal electronic communication between the boron centers, as evidenced by two closely spaced reduction processes. The UV-vis spectra showed bathochromic shifted absorption bands compared to related monoboranes, which is attributed to the methylene bridge. A further red-shift results upon introduction of methyl or SiMe\(_3\) groups at the terminal thiophene rings.
KW  - Boron
KW  - thiophene
KW  - conjugated oligomers
KW  - hybrid materials
KW  - boranes
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-258020
VL  - 647
IS  - 5
ER  - 
TY  - JOUR
A1  - He, Jiang
A1  - Rauch, Florian
A1  - Friedrich, Alexandra
A1  - Krebs, Johannes
A1  - Krummenacher, Ivo
A1  - Bertermann, Rüdiger
A1  - Nitsch, Jörn
A1  - Braunschweig, Holger
A1  - Finze, Maik
A1  - Marder, Todd B.
T1  - Phenylpyridyl-fused boroles: a unique coordination mode and weak B-N coordination-induced dual fluorescence
JF  - Angewandte Chemie International Edition
N2  - Phenylpyridyl-fused boroles [TipPBB1]\(_4\) and TipPBB2 were synthesized and their properties investigated. [TipPBB1]\(_4\) forms a tetramer in both the solid state and solution. TipPBB2 contains a 4-coordinate boron atom in the solid state but dissociates to give a 3-coordinate boron species in solution. TipPBB2 shows interesting temperature-dependent dual fluorescence in solution because of the equilibrium between 3- and 4-coordinate boron species due to weak N⋅⋅⋅B intermolecular coordination.
KW  - inorganic chemistry
KW  - weak intermolecular coordination
KW  - boroles
KW  - dual fluorescence
KW  - equilibrium
KW  - tetramers
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256423
VL  - 60
IS  - 9
ER  - 
TY  - JOUR
A1  - Krebs, Johannes
A1  - Haehnel, Martin
A1  - Krummenacher, Ivo
A1  - Friedrich, Alexandra
A1  - Braunschweig, Holger
A1  - Finze, Maik
A1  - Ji, Lei
A1  - Marder, Todd B.
T1  - Synthesis and Structure of an o-Carboranyl-Substituted Three-Coordinate Borane Radical Anion
JF  - Chemistry—A European Journal
N2  - Bis(1-(4-tolyl)-carboran-2-yl)-(4-tolyl)-borane [(1-(4-MeC\(_{6}\)H\(_{4}\))-closo-1,2-C\(_{2}\)B\(_{10}\)H\(_{10}\)-2-)\(_{2}\)(4-MeC\(_{6}\)H\(_{4}\))B] (1), a new bis(o-carboranyl)-(R)-borane was synthesised by lithiation of the o-carboranyl precursor and subsequent salt metathesis reaction with (4-tolyl)BBr\(_{2}\). Cyclic voltammetry experiments on 1 show multiple distinct reduction events with a one-electron first reduction. In a selective reduction experiment the corresponding paramagnetic radical anion 1\(^{.−}\) was isolated and characterized. Single-crystal structure analyses allow an in-depth comparison of 1, 1\(^{.−}\), their calculated geometries, and the S\(_{1}\) excited state of 1. Photophysical studies of 1 show a charge transfer (CT) emission with low quantum yield in solution but a strong increase in the solid state. TD-DFT calculations were used to identify transition-relevant orbitals.
KW  - Wade’s rules
KW  - carborane
KW  - charge transfer
KW  - radical
KW  - threecoordinate boron
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256841
VL  - 27
IS  - 31
ER  - 
TY  - JOUR
A1  - Arrowsmith, Merle
A1  - Endres, Sara
A1  - Heinz, Myron
A1  - Nestler, Vincent
A1  - Holthausen, Max C.
A1  - Braunschweig, Holger
T1  - Probing the Boundaries between Lewis-Basic and Redox Behavior of a Parent Borylene
JF  - Chemistry—A European Journal
N2  - The parent borylene (CAAC)(Me\(_{3}\)P)BH, 1 (CAAC=cyclic alkyl(amino)carbene), acts both as a Lewis base and one-electron reducing agent towards group 13 trichlorides (ECl\(_{3}\), E=B, Al, Ga, In), yielding the adducts 1-ECl\(_{3}\) and increasing proportions of the radical cation [1]\(^{•+}\) for the heavier group 13 analogues. With boron trihalides (BX\(_{3}\), X=F, Cl, Br, I) 1 undergoes sequential adduct formation and halide abstraction reactions to yield borylboronium cations and shows an increasing tendency towards redox processes for the heavier halides. Calculations confirm that 1 acts as a strong Lewis base towards EX3 and show a marked increase in the B−E bond dissociation energies down both group 13 and the halide group.
KW  - redox processes
KW  - bond dissociation energies
KW  - borylene
KW  - group 13
KW  - Lewis adducts
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-257154
VL  - 27
IS  - 70
ER  - 
TY  - JOUR
A1  - Brückner, Tobias
A1  - Fantuzzi, Felipe
A1  - Stennett, Tom E.
A1  - Krummenacher, Ivo
A1  - Dewhurst, Rian D.
A1  - Engels, Bernd
A1  - Braunschweig, Holger
T1  - Isolation of neutral, mono-, and dicationic B\(_2\)P\(_2\) rings by diphosphorus addition to a boron-boron triple bond
JF  - Angewandte Chemie International Edition
N2  - The NHC-stabilised diboryne (B\(_2\)(SIDep)\(_2\); SIDep=1,3-bis(2,6-diethylphenyl)imidazolin-2-ylidene) undergoes a high-yielding P−P bond activation with tetraethyldiphosphine at room temperature to form a B\(_2\)P\(_2\) heterocycle via a diphosphoryldiborene by 1,2-diphosphination. The heterocycle can be oxidised to a radical cation and a dication, respectively, depending on the oxidant used and its counterion. Starting from the planar, neutral 1,3-bis(alkylidene)-1,3-diborata-2,4-diphosphoniocyclobutane, each oxidation step leads to decreased B−B distances and loss of planarity by cationisation. X-ray analyses in conjunction with DFT and CASSCF/NEVPT2 calculations reveal closed-shell singlet, butterfly-shaped structures for the NHC-stabilised dicationic B\(_2\)P\(_2\) rings, with their diradicaloid, planar-ring isomers lying close in energy.
KW  - inorganic chemistry
KW  - radicals
KW  - boron
KW  - density functional calculations
KW  - oxidation
KW  - phosphorus heterocycles
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256451
VL  - 60
IS  - 24
ER  - 
TY  - JOUR
A1  - Hagspiel, Stephan
A1  - Fantuzzi, Felipe
A1  - Dewhurst, Rian D.
A1  - Gärtner, Annalena
A1  - Lindl, Felix
A1  - Lamprecht, Anna
A1  - Braunschweig, Holger
T1  - Addukte des Stammboraphosphaketens H\(_{2}\)BPCO und deren Insertionsreaktionen mittels Decarbonylierung
JF  - Angewandte Chemie
N2  - Die ersten Beispiele für Lewis-Basen-Addukte des Stammboraphosphaketens H\(_{2}\)B-PCO und ihre cyclischen Dimere wurden hergestellt. Eines dieser Addukte zeigt unter milden Bedingungen eine Decarbonylierung und anschließende Insertion des Phosphinidens in die B-C-Bindung eines Borols, was in der Bildung sehr seltener Beispiele für 1,2-Phosphaborinine, B,P-Isostere von Benzol, resultiert. Die starken Donoreigenschaften dieser 1,2-Phosphaborinine wurden durch die Synthese ihrer π-Komplexe mit Metallen der Gruppe 6 bestätigt.
KW  - Bor
KW  - Decarbonylierung
KW  - Heterocyclen
KW  - Ketene
KW  - Phosphor
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-244803
VL  - 133
IS  - 24
SP  - 13780
EP  - 13784
ER  -