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  - Bachmann, Jonas
A1  - Helbig, Andreas
A1  - Crumbach, Merian
A1  - Krummenacher, Ivo
A1  - Braunschweig, Holger
A1  - Helten, Holger
T1  - Fusion of Aza‐ and Oxadiborepins with Furans in a Reversible Ring‐Opening Process Furnishes Versatile Building Blocks for Extended π‐Conjugated Materials
JF  - Chemistry – A European Journal
N2  - A modular synthesis of both difurooxa‐ and difuroazadiborepins from a common precursor is demonstrated. Starting from 2,2′‐bifuran, after protection of the positions 5 and 5’ with bulky silyl groups, formation of the novel polycycles proceeds through opening of the furan rings to a dialkyne and subsequent re‐cyclization in the borylation step. The resulting bifuran‐fused diborepins show pronounced stability, highly planar tricyclic structures, and intense blue light emission. Deprotection and transformation into dibrominated building blocks that can be incorporated into π‐extended materials can be performed in one step. Detailed DFT calculations provide information about the aromaticity of the constituent rings of this polycycle.
KW  - aromaticity
KW  - boron
KW  - BN compounds
KW  - furan
KW  - polycycles
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-293926
VL  - 28
IS  - 63
ER  - 
TY  - JOUR
A1  - Crumbach, Merian
A1  - Bachmann, Jonas
A1  - Fritze, Lars
A1  - Helbig, Andreas
A1  - Krummenacher, Ivo
A1  - Braunschweig, Holger
A1  - Helten, Holger
T1  - Dithiophene‐Fused Oxadiborepins and Azadiborepins: A New Class of Highly Fluorescent Heteroaromatics
JF  - Angewandte Chemie International Edition
N2  - Access to dithiophene‐fused oxadiborepins and the first azadiborepins attained via a modular synthesis route are presented. The new compounds emit intense blue light, some of which demonstrate fluorescence quantum yields close to unity. Cyclic voltammetry (CV) revealed electrochemically reversible one‐electron reduction processes. The weak aromatic character of the novel 1,2,7‐azadiborepin ring is demonstrated with in‐depth theoretical investigations using nucleus‐independent chemical shift (NICS) scans and anisotropy of the induced current density (ACID) calculations.
KW  - aromaticity
KW  - BN compounds
KW  - boron
KW  - isoelectronic analogues
KW  - polycycles
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-238996
VL  - 60
IS  - 17
SP  - 9290
EP  - 9295
ER  - 
TY  - JOUR
A1  - Schorr, Fabian
A1  - Schopper, Nils
A1  - Riensch, Nicolas
A1  - Fantuzzi, Felipe
A1  - Neder, Marco
A1  - Dewhurst, Rian D.
A1  - Thiess, Thorsten
A1  - Brückner, Tobias
A1  - Hammond, Kai
A1  - Helten, Holger
A1  - Finze, Maik
A1  - Braunschweig, Holger
T1  - Controlled Synthesis of Oligomers Containing Main-Chain B(sp\(^{2}\))-B(sp\(^{2}\)) Bonds
JF  - Chemistry—A European Journal
N2  - A number of novel alkynyl-functionalized diarylbis(dimethylamino)diboranes(4) are prepared by salt metathesis, and the appended alkynyl groups are subjected to hydroboration. Their reactions with monohydroboranes lead to discrete boryl-appended diborane(4) species, while dihydroboranes induce their catenation to oligomeric species, the first known examples of well-characterized macromolecular species with B−B bonds. The oligomeric species were found to comprise up to ten repeat units and are soluble in common organic solvents. Some of the oligomeric species have good air stability and all were characterized by NMR and vibrational spectroscopy and size-exclusion chromatography techniques.
KW  - oligomerization
KW  - boron
KW  - catenation
KW  - diborane
KW  - hydroboration
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-257274
VL  - 27
IS  - 64
ER  - 
TY  - JOUR
A1  - Auerhammer, Dominic
A1  - Arrowsmith, Merle
A1  - Braunschweig, Holger
A1  - Dewhurst, Rian D.
A1  - Jiménez-Halla, J. Oscar C.
A1  - Kupfer, Thomas
T1  - Nucleophilic addition and substitution at coordinatively saturated boron by facile 1,2-hydrogen shuttling onto a carbene donor
JF  - Chemical Science
N2  - The reaction of [(cAAC\(^{Me}\))BH\(_{3}\)] (cAAC\(^{Me}\) = 1-(2,6-iPr\(_{2}\)C\(_{6}\)H\(_{3}\))-3,3,5,5-tetramethylpyrrolidin-2-ylidene) with a range of organolithium compounds led to the exclusive formation of the corresponding (dihydro)organoborates, Li\(^{+}\)[(cAAC\(^{Me}\)H)BH\(_{2}\)R]− (R = sp\(^{3}\)-, sp\(^{2}\)-, or sp-hybridised organic substituent), by migration of one boron-bound hydrogen atom to the adjacent carbene carbon of the cAAC ligand. A subsequent deprotonation/salt metathesis reaction with Me3SiCl or spontaneous LiH elimination yielded the neutral cAAC-supported mono(organo)boranes, [(cAAC\(^{Me}\)H)BH\(_{2}\)R]− (R]. Similarly the reaction of [cAAC\(^{Me}\))BH\(_{3}\)] with a neutral donor base L resulted in adduct formation by shuttling one boron-bound hydrogen to the cAAC ligand, to generate [(cAAC\(^{Me}\)H)BH\(_{2}\)L], either irreversibly (L = cAAC\(^{Me}\)) or reversibly (L = pyridine). Variable-temperature NMR data and DFT calculations on [(cAAC\(^{Me}\)H)BH\(_{2}\)(cAAC\(^{Me}\))] show that the hydrogen on the former carbene carbon atom exchanges rapidly with the boron-bound hydrides.
KW  - nucleophilic addition
KW  - nucleophilic substitution
KW  - boron-bound hydrogen
KW  - carbene donor
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-170255
VL  - 8
IS  - 10
ER  - 
TY  - INPR
A1  - Auerhammer, Dominic
A1  - Arrowsmith, Merle
A1  - Bissinger, Philipp
A1  - Braunschweig, Holger
A1  - Dellermann, Theresa
A1  - Kupfer, Thomas
A1  - Lenczyk, Carsten
A1  - Roy, Dipak
A1  - Schäfer, Marius
A1  - Schneider, Christoph
T1  - Increasing the Reactivity of Diborenes: Derivatization of NHC- Supported Dithienyldiborenes with Electron-Donor Groups
T2  - Chemistry, A European Journal
N2  - A series of NHC-supported 1,2-dithienyldiborenes was synthesized from the corresponding (dihalo)thienylborane NHC precursors. NMR and UV-vis spectroscopic data, as well as X-ray crystallographic analyses, were used to assess the electronic and steric influences on the B=B double bond of various NHCs and electron-donating substituents on the thienyl ligands. Crystallographic data showed that the degree of coplanarity of the diborene core and thienyl groups is highly dependent on the sterics of the substituents. Furthermore, any increase in the electron- donating ability of the substituents resulted in the destabilization of the HOMO and greater instability of the resulting diborenes.
KW  - diborenes
KW  - N-heterocyclic carbenes
KW  - electron donors
KW  - structural analysis
KW  - spectroscopy
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-155419
N1  - This is the pre-peer reviewed version of the following article: Auerhammer, D., Arrowsmith, M., Bissinger, P., Braunschweig, H., Dellermann, T., Kupfer, T., Lenczyk, C., Roy, D. K., Schäfer, M. and Schneider, C. (2017), Increasing the Reactivity of Diborenes: Derivatization of NHC-Supported Dithienyldiborenes with Electron-Donor Groups. Chem. Eur. J.. doi:10.1002/chem.201704669, which has been published in final form at doi:10.1002/chem.201704669. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
ER  - 
TY  - INPR
A1  - Auerhammer, Dominic
A1  - Arrowsmith, Merle
A1  - Böhnke, Julian
A1  - Braunschweig, Holger
A1  - Dewhurst, Rian D.
A1  - Kupfer, Thomas
T1  - Brothers from Another Mother: a Borylene and its Dimer are Non-Interconvertible but Connected through Reactivity
T2  - Chemical Science
N2  - The self-stabilizing, tetrameric cyanoborylene [(cAAC)B(CN)]4 (I, cAAC = 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) and its diborene relative, [(cAAC)(CN)B=B(CN)(cAAC)] (II), both react with disulfides and diselenides to yield the corresponding cAAC-supported cyanoboron bis(chalcogenides). Furthermore, reactions of I or II with elemental sulfur and selenium in various stoichiometries provided access to a variety of cAAC- stabilized cyanoboron-chalcogen heterocycles, including a unique dithiaborirane, a diboraselenirane, 1,3-dichalcogena-2,4-diboretanes, 1,3,4-trichalcogena- 2,5-diborolanes and a rare six-membered 1,2,4,5-tetrathia-3,6-diborinane. Stepwise addition reactions and solution stability studies provided insights into the mechanism of these reactions and the subtle differences in reactivity observed between I and II.
KW  - borylenes
KW  - diborenes
KW  - boron
KW  - carbenes
KW  - chalcogens
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-157125
ER  - 
TY  - INPR
A1  - Böhnke, Julian
A1  - Braunschweig, Holger
A1  - Jiménez-Halla, Oscar
A1  - Krummenacher, Ivo
A1  - Stennett, Tom E.
T1  - Half-Sandwich Complexes of an Extremely Electron-Donating, Re-dox-Active η\(^6\)-Diborabenzene Ligand
T2  - Journal of the American Chemical Society
N2  - The heteroarene 1,4-bis(CAAC)-1,4-diborabenzene (1; CAAC = cyclic (alkyl)(amino)carbene) reacts with [(MeCN)\(_3\)M(CO)\(_3\)] (M = Cr, Mo, W) to yield half-sandwich complexes of the form [(η\(^6\)-diborabenzene)M(CO)\(_3\)] (M = Cr (2), Mo (3), W (4)). Investigation of the new complexes with a combination of X-ray diffraction, spectroscopic methods and DFT calculations shows that ligand 1 is a remarkably strong electron donor. In particular, [(η\(^6\)-arene)M(CO)\(_3\)] complexes of this ligand display the lowest CO stretching frequencies yet observed for this class of complex. Cyclic voltammetry on complexes 2-4 revealed one reversi- ble oxidation and two reversible reduction events in each case, with no evidence of ring-slippage of the arene to the η\(^4\) binding mode. Treatment of 4 with lithium metal in THF led to identification of the paramagnetic complex [(1)W(CO)\(_3\)]Li·2THF (5). Compound 1 can also be reduced in the absence of a transition metal to its dianion 1\(^{2–}\), which possesses a quinoid-type structure.
KW  - half-sandwich complexes
KW  - transition metal complex
KW  - boron
KW  - redox reactions
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-156766
N1  - This document is the unedited Author's version of a Submitted Work that was subsequently accepted for publication in Journal of the American Chemical Society, copyright © 2017 American Chemical Society after peer review. To access the final edited and published work see dx.doi.org/10.1021/jacs.7b12394.
ER  - 
TY  - INPR
A1  - Stoy, Andreas
A1  - Böhnke, Julian
A1  - Jiménez-Halla, J. Oscar C.
A1  - Dewhurst, Rian D.
A1  - Thiess, Torsten
A1  - Braunschweig, Holger
T1  - CO\(_2\) Binding and Splitting by Boron–Boron Multiple Bonds
T2  - Angewandte Chemie, International Edition
N2  - CO\(_2\) is found to undergo room-temperature, ambient- pressure reactions with two species containing boron-boron multiple bonds, leading to incorporation of either one or two CO\(_2\) molecules. In one case, a thermally-unstable intermediate was structurally characterized, indicating the operation of an initial 2+2 cycloaddition mechanism in the reaction.
KW  - carbon dioxide
KW  - CO2 fixation
KW  - diborenes
KW  - diborynes
KW  - boron
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-164265
N1  - This is the pre-peer reviewed version of the following article: A. Stoy, J. Böhnke, J. O. C. Jiménez‐Halla, R. D. Dewhurst, T. Thiess, H. Braunschweig, Angew. Chem. Int.Ed. 2018, 57,5947 –5951, which has been published in final form at DOI: 10.1002/anie.201802117. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
ER  - 
TY  - INPR
A1  - Arrowsmith, Merle
A1  - Mattock, James D.
A1  - Böhnke, Julian
A1  - Krummenacher, Ivo
A1  - Vargas, Alfredo
A1  - Braunschweig, Holger
T1  - Direct access to a cAAC-supported dihydrodiborene and its dianion
T2  - Chemical Communications
N2  - The two-fold reduction of (cAAC)BHX\(_2\) (cAAC = 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene; X = Cl, Br) provides a facile, high-yielding route to the dihydrodiborene (cAAC)\(_2\)B\(_2\)H\(_2\). The (chloro)hydroboryl anion reduction intermediate was successfully isolated using a crown ether. Overreduction of the diborene to its dianion [(cAAC)\(_2\)B\(_2\)H\(_2\)]\(^{2−}\) causes a decrease in the B–B bond order whereas the B–C bond orders increase.
KW  - carbenes
KW  - diborenes
KW  - boron
KW  - main-group chemistry
KW  - diborynes
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-164276
N1  - This is the pre-peer reviewed version of the following article: Chemical Communications, 2018, 54, 4669-4672 which has been published at DOI: 10.1039/C8CC01580E
ER  - 
TY  - JOUR
A1  - Böhnke, Julian
A1  - Brückner, Tobias
A1  - Hermann, Alexander
A1  - González-Belman, Oscar F.
A1  - Arrowsmith, Merle
A1  - Jiménez-Halla, J. Oscar C.
A1  - Braunschweig, Holger
T1  - Single and double activation of acetone by isolobal B≡N and B≡B triple bonds
JF  - Chemical Science
N2  - B≡N and B≡B triple bonds induce C-H activation of acetone to yield a (2-propenyloxy)aminoborane and an unsymmetrical 1-(2- propenyloxy)-2-hydrodiborene, respectively. DFT calculations showed that, despite their stark electronic differences, both the B≡N and B≡B triple bonds activate acetone via a similar coordination-deprotonation mechansim. In contrast, the reaction of acetone with a cAAC-supported diboracumulene yielded a unique 1,2,3-oxadiborole, which according to DFT calculations also proceeds via an unsymmetrical diborene, followed by intramolecular hydride migration and a second C-H activation of the enolate ligand.
KW  - acetone
KW  - diborynes
KW  - iminoboranes
KW  - boron
KW  - small-molecule activation
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-164286
VL  - 9
ER  - 
TY  - INPR
A1  - Cid, Jessica
A1  - Hermann, Alexander
A1  - Radcliffe, James E.
A1  - Curless, Liam D.
A1  - Braunschweig, Holger
A1  - Ingleson, Michael J.
T1  - Synthesis of Unsymmetrical Diboron(5) Compounds and Their Conversion to Diboron(5) Cations
T2  - Organometallics
N2  - Reaction of bis-catecholatodiboron-NHC adducts, B\(_2\)Cat\(_2\)(NHC), (NHC = IMe (tetramethylimidazol-2-ylidene), IMes (1,3-dimesitylimidazol-2-ylidene) or IDIPP (1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene)) with BCl3 results in the replacement of the catecholato group bound to the four coordinate boron with two chlorides to yield diboron(5) Lewis acid-base adducts of formula CatB-BCl\(_2\)(NHC). These compounds are precursors to diboron(5) monocations, accessed by adding AlCl\(_3\) or K[B(C\(_6\)F\(_5\))\(_4\)] as halide abstraction agents in the presence of a Lewis base. The substitution of the chlorides of CatB-BCl\(_2\)(NHC) for hydrides is achieved using Bu\(_3\)SnH and a halide abstracting agent to form 1,1-dihydrodiboron(5) compounds, CatB-BH\(_2\)(NHC). Attempts to generate diboron(4) monocations of formula [CatB-B(Y)(NHC)]\(^+\) (Y = Cl or H) led to the rapid formation of CatBY.
KW  - diboron
KW  - boronium cations
KW  - boron
KW  - Lewis acids
KW  - electrophiles
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-164299
N1  - This document is the unedited Author's version of a Submitted Work that was subsequently accepted for publication in Organometallics, copyright © 2018 American Chemical Society after peer review. To access the final edited and published work see dx.doi.org/10.1021/acs.organomet.8b00288
ER  - 
TY  - INPR
A1  - Wang, Sunewang Rixin
A1  - Arrowsmith, Merle
A1  - Braunschweig, Holger
A1  - Dewhurst, Rian
A1  - Paprocki, Valerie
A1  - Winner, Lena
T1  - CuOTf-mediated intramolecular diborene hydroarylation
T2  - Chemical Communications
N2  - Upon complexation to CuOTf, a PMe\(_3\)-stabilized bis(9-anthryl) diborene slowly undergoes an intramolecular hydroarylation reaction at room temperature. Subsequent triflation of the B–H bond with CuOTf, followed by a PMe\(_3\) transfer, finally yields a cyclic sp\(^2\)-sp\(^3\) boryl-substituted boronium triflate salt.
KW  - boron
KW  - C-H activation
KW  - transition metals
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-154055
N1  - This is the pre-peer reviewed version of the following article: Chemical Communications, 2017, 11945-11947 which has been published at DOI: 10.1039/C7CC07371B.
ER  - 
TY  - INPR
A1  - Braunschweig, Holger
A1  - Brückner, Tobias
A1  - Deißenberger, Andrea
A1  - Dewhurst, Rian
A1  - Gackstatter, Annika
A1  - Gärtner, Annalena
A1  - Hofmann, Alexander
A1  - Kupfer, Thomas
A1  - Prieschl, Dominic
A1  - Thiess, Torsten
A1  - Wang, Sunewang Rixin
T1  - Reaction of Dihalodiboranes(4) with N-Heterocyclic Silylenes: Facile Construction of 1-Aryl-2-Silyl-1,2-Diboraindanes
T2  - Chemistry, A European Journal
N2  - Dihalodiboranes(4) react with an N-heterocyclic silylene (NHSi) to generate NHSi-adducts of 1-aryl-2-silyl-1,2-diboraindanes as confirmed by X-ray crystallography, featuring the functionalization of both B–X (X = halogen) bonds and a C–H bond under mild conditions. Coordination of a third NHSi to the proposed 1,1-diaryl- 2,2-disilyldiborane(4) intermediates, generated by a two-fold B–X insertion, may be crucial for the C–H borylation that leads to the final products. Notably, our results demonstrate the first C–H borylation with a strong B–F bond activated by silylene insertion.
KW  - diborane
KW  - boron
KW  - silylenes
KW  - CH activation
KW  - bond activation
KW  - diboraindanes
KW  - diboranes
KW  - synthetic methods
KW  - borylation
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-153068
N1  - This is the pre-peer reviewed version of the following article: H. Braunschweig, T. Brückner, A. Deißenberger, R. D. Dewhurst, A. Gackstatter, A. Gärtner, A. Hofmann, T. Kupfer, D. Prieschl, T. Thiess, S. R. Wang, Reaction of Dihalodiboranes(4) with a N-Heterocyclic Silylene: Facile Construction of 1-Aryl-2-Silyl-1,2-Diboraindanes, Chem. Eur. J. 2017, 23, 9491., which has been published in final form at dx.doi.org/10.1002/chem.201702377. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving
ER  - 
TY  - INPR
A1  - Arrowsmith, Merle
A1  - Böhnke, Julian
A1  - Braunschweig, Holger
A1  - Celik, Mehmet Ali
T1  - Reactivity of a Dihydrodiborene with CO: Coordination, Insertion, Cleavage and Spontaneous Cyclic Alkyne Formation
T2  - Angewandte Chemie, International Edition
N2  - Under a CO atmosphere the dihydrodiborene [(cAAC)HB=BH(cAAC)] underwent coordination of CO concomitant with reversible hydrogen migration from boron to the carbene carbon atom, as well as reversible CO insertion into the B=B bond. Heating of the CO-adduct resulted in two unusual cAAC ring-expansion products, one presenting a B=C bond to a six-membered 1,2-azaborinane-3-ylidene, the other an unprecedented nine-membered cyclic alkyne resulting from reductive cleavage of CO and spontaneous C≡C triple bond formation.
KW  - CO activation
KW  - diborene
KW  - ring expansion
KW  - insertion
KW  - cyclic (alkyl)(amino)carbene
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-153318
N1  - This is the pre-peer reviewed version of the following article: Arrowsmith, M., Böhnke, J., Braunschweig, H. and Celik, M., Reactivity of a Dihydrodiborene with CO: Coordination, Insertion, Cleavage and Spontaneous Cyclic Alkyne Formation. Angew. Chem. Int. Ed. 2017, 129,14475 –14480. Accepted Author Manuscript. doi:10.1002/anie.201707907. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
ER  - 
TY  - INPR
A1  - Böhnke, Julian
A1  - Dellermann, Theresa
A1  - Celik, Mehmet Ali
A1  - Krummenacher, Ivo
A1  - Dewhurst, Rian D.
A1  - Demeshko, Serhiy
A1  - Ewing, William C.
A1  - Hammond, Kai
A1  - Heß, Merlin
A1  - Bill, Eckhard
A1  - Welz, Eileen
A1  - Röhr, Merle I. S.
A1  - Mitric, Roland
A1  - Engels, Bernd
A1  - Meyer, Franc
A1  - Braunschweig, Holger
T1  - Isolation of diradical products of twisted double bonds
T2  - Nature Communications
N2  - Molecules containing multiple bonds between atoms—most often in the form of olefins—are ubiquitous in nature, commerce, and science, and as such have a huge impact on everyday life. Given their prominence, over the last few decades, frequent attempts have been made to perturb the structure and reactivity of multiply-bound species through bending and twisting. However, only modest success has been achieved in the quest to completely twist double bonds in order to homolytically cleave the associated π bond. Here, we present the isolation of double-bond-containing species based on boron, as well as their fully twisted diradical congeners, by the incorporation of attached groups with different electronic properties. The compounds comprise a structurally authenticated set of diamagnetic multiply-bound and diradical singly-bound congeners of the same class of compound.
KW  - diradicals
KW  - diborenes
KW  - carbenes
KW  - boron
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-160248
N1  - Submitted version of Julian Böhnke, Theresa Dellermann, Mehmet Ali Celik, Ivo Krummenacher, Rian D. Dewhurst, Serhiy Demeshko, William C. Ewing, Kai Hammond, Merlin Heß, Eckhard Bill, Eileen Welz, Merle I. S. Röhr, Roland Mitrić, Bernd Engels, Franc Meyer & Holger Braunschweig: Isolation of diborenes and their 90°-twisted diradical congeners. Nature Communications. Volume 9, Article number: 1197 (2018) doi:10.1038/s41467-018-02998-3
ER  - 
TY  - INPR
A1  - Stennett, Tom
A1  - Mattock, James
A1  - Vollert, Ivonne
A1  - Vargas, Alfredo
A1  - Braunschweig, Holger
T1  - Unsymmetrical, Cyclic Diborenes and Thermal Rearrangement to a Borylborylene
T2  - Angewandte Chemie, International Edition
N2  - Cyclic diboranes(4) based on a chelating monoanionic, benzylphosphine linker were prepared by boron-silicon exchange between arylsilanes and B\(_2\)Br\(_4\). Coordination of Lewis bases to the remaining sp\(^2\) boron atom yielded unsymmetrical sp\(^3\)-sp\(^3\) diboranes, which were reduced with KC\(_8\) to their corresponding trans-diborenes. These compounds were studied by a combination of spectroscopic methods, X-ray diffraction and DFT calculations. PMe\(_3\)-stabilized diborene 6 was found to undergo thermal rearrangement to gem- diborene 8. DFT calculations on 8 reveal a polar boron-boron bond, and indicate that the compound is best described as a borylborylene.
KW  - boron
KW  - borylene
KW  - multiple bonds
KW  - rearrangement
KW  - DFT calculations
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-160258
N1  - This is the pre-peer reviewed version of the following article: T. E. Stennett, J. D. Mattock, I. Vollert, A. Vargas, H. Braunschweig, Angew. Chem. Int. Ed. 2018, 57, 4098., which has been published in final form at DOI: 10.1002/anie.201800671. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
VL  - 57
ER  - 
TY  - INPR
A1  - Arrowsmith, Merle
A1  - Böhnke, Julian
A1  - Braunschweig, Holger
A1  - Celik, Mehmet
A1  - Claes, Christina
A1  - Ewing, William
A1  - Krummenacher, Ivo
A1  - Lubitz, Katharina
A1  - Schneider, Christoph
T1  - Neutral Diboron Analogues of Archetypal Aromatic Species by Spontaneous Cycloaddition
N2  - Among the numerous routes organic chemists have developed to synthesize benzene derivatives and heteroaro- matic compounds, transition-metal-catalyzed cycloaddition reactions are the most elegant. In contrast, cycloaddition reactions of heavier alkene and alkyne analogues, though limited in scope, proceed uncatalyzed. In this work we present the first spontaneous cycloaddition reactions of lighter alkene and alkyne analogues. Selective addition of unactivated alkynes to boron–boron multiple bonds under ambient con- ditions yielded diborocarbon equivalents of simple aromatic hydrocarbons, including the first neutral 6p-aromatic dibora- benzene compound, a 2 p-aromatic triplet biradical 1,3-dibor- ete, and a phosphine-stabilized 2 p-homoaromatic 1,3-dihydro- 1,3-diborete. DFT calculations suggest that all three com- pounds are aromatic and show frontier molecular orbitals matching those of the related aromatic hydrocarbons, C6H6 and C4H42+, and homoaromatic C4H5+.
KW  - Aromaticity
KW  - Biradicals
KW  - Boron
KW  - Cycloaddition
KW  - Multiple bonds
KW  - Diborane
KW  - Cycloaddition
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-142500
ER  - 
TY  - INPR
A1  - Wang, Sunewang R.
A1  - Arrowsmith, Merle
A1  - Böhnke, Julian
A1  - Braunschweig, Holger
A1  - Dellermann, Theresa
A1  - Dewhurst, Rian D.
A1  - Kelch, Hauke
A1  - Krummenacher, Ivo
A1  - Mattock, James D.
A1  - Müssig, Jonas H.
A1  - Thiess, Torsten
A1  - Vargas, Alfredo
A1  - Zhang, Jiji
T1  - Engineering a Small HOMO-LUMO Gap and Intramolecular B–B Hydroarylation by Diborene/Anthracene Orbital Intercalation
T2  - Angewandte Chemie, International Edition
N2  - The diborene 1 was synthesized by reduction of a mixture of 1,2-di-9-anthryl-1,2-dibromodiborane(4) (6) and trimethylphosphine with potassium graphite. The X-ray structure of 1 shows the two anthryl rings to be parallel and their π(C\(_{14}\)) systems perpendicular to the diborene π(B=B) system. This twisted conformation allows for intercalation of the relatively high-lying π(B=B) orbital and the low-lying π* orbital of the anthryl moiety with no significant conjugation, resulting in a small HOMO-LUMO gap (HLG) and ultimately an unprecedented anthryl B–B bond hydroarylation. The HLG of 1 was estimated to be 1.57 eV from the onset of the long wavelength band in its UV–vis absorption spectrum (THF, λ\(_{onset}\) = 788 nm). The oxidation of 1 with elemental selenium afforded diboraselenirane 8 in quantitative yield. By oxidative abstraction of one phosphine ligand by another equivalent of elemental selenium, the B–B and C\(^1\)–H bonds of 8 were cleaved to give the cyclic 1,9-diboraanthracene 9.
KW  - boron
KW  - small HOMO-LUMO gap
KW  - diborenes
KW  - borylation
KW  - hydroarylation
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148126
N1  - This is the pre-peer reviewed version of the following article: S. R. Wang, M. Arrowsmith, J. Böhnke, H. Braunschweig, T. Dellermann, R. D. Dewhurst, H. Kelch, I. Krummenacher, J. D. Mattock, J. H. Müssig, T. Thiess, A. Vargas, J. Zhang, Angew. Chem. Int. Ed. 2017, 56, 8009., which has been published in final form at DOI: 10.1002/anie.201704063. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
VL  - 56
IS  - 27
ER  - 
TY  - INPR
A1  - Braunschweig, Holger
A1  - Krummenacher, Ivo
A1  - Lichtenberg, Crispin
A1  - Mattock, James
A1  - Schäfer, Marius
A1  - Schmidt, Uwe
A1  - Schneider, Christoph
A1  - Steffenhagen, Thomas
A1  - Ullrich, Stefan
A1  - Vargas, Alfredo
T1  - Dibora[2]ferrocenophane: A Carbene-Stabilized Diborene in a Strained cis-Configuration
T2  - Angewandte Chemie, International Edition
N2  - Unsaturated bridges that link the two cyclopentadienyl ligands together in strained ansa metallocenes are rare and limited to carbon-carbon double bonds. The synthesis and isolation of a strained ferrocenophane containing an unsaturated two-boron bridge, isoelectronic with a C=C double bond, was achieved by reduction of a carbene-stabilized 1,1’-bis(dihaloboryl)ferrocene. A combination of spectroscopic and electrochemical measurements as well as density functional theory (DFT) calculations was used to assess the influence of the unprecedented strained cis configuration on the optical and electrochemical properties of the carbene-stabilized diborene unit. Initial reactivity studies show that the dibora[2]ferrocenophane is prone to boron-boron double bond cleavage reactions.
KW  - Boron
KW  - Metallocenes
KW  - Metallocene
KW  - Bor
KW  - Diborane
KW  - density functional calculations
KW  - strained molecules
KW  - diborenes
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-141981
N1  - This is the pre-peer reviewed version of the following article: Angewandte Chemie, International Edition, Volume 56, Issue 3, 889–892, which has been published in final form at doi:10.1002/anie.201609601. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
ER  - 
TY  - INPR
A1  - Arrowsmith, Merle
A1  - Böhnke, Julian
A1  - Braunschweig, Holger
A1  - Deißenberger, Andrea
A1  - Dewhurst, Rian
A1  - Ewing, William
A1  - Hörl, Christian
A1  - Mies, Jan
A1  - Muessig, Jonas
T1  - Simple Solution-Phase Syntheses of Tetrahalodiboranes(4) and their Labile Dimethylsulfide Adducts
T2  - Chemical Communications
N2  - Convenient, solution-phase syntheses of tetrahalodiboranes(4) B\(_2\)F\(_4\), B\(_2\)Cl\(_4\) and B\(_2\)I\(_4\) are presented herein from common precursor B\(_2\)Br\(_4\). In addition, the dimethylsulfide adducts B\(_2\)Cl\(_4\)(SMe\(_2\))\(_2\) and B\(_2\)Br\(_4\)(SMe\(_2\))\(_2\) are conveniently prepared in one-step syntheses from the commercially-available starting material B\(_2\)(NMe\(_2\))\(_4\). The results provide simple access to the full range of tetrahalodiboranes(4) for the exploration of their untapped synthetic potential.
KW  - Boron
KW  - Diboranes
KW  - Tetrafluorodiborane
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-149438
N1  - This is the pre-peer reviewed version of the following article: Chemical Communications, 2017,53, 8265-8267, which has been published in final form at doi:10.1039/C7CC03148C.
VL  - 53
ER  - 
TY  - INPR
A1  - Hermann, Alexander
A1  - Cid, Jessica
A1  - Mattock, James D.
A1  - Dewhurst, Rian D.
A1  - Krummenacher, Ivo
A1  - Vargas, Alfredo
A1  - Ingleson, Michael J.
A1  - Braunschweig, Holger
T1  - Diboryldiborenes: π‐Conjugated B\(_4\) Chains Isoelectronic to the Butadiene Dication
T2  - Angewandte Chemie, International Edition
N2  - sp\(^2\)–sp\(^3\) diborane species based on bis(catecholato)diboron and N-heterocyclic carbenes (NHCs) are subjected to catechol/bromide exchange selectively at the sp\(^3\) boron atom. The reduction of the resulting 1,1-dibromodiborane adducts led to reductive coupling and isolation of doubly NHC-stabilized 1,2-diboryldiborenes. These compounds are the first examples of molecules exhibiting pelectron delocalization over an all-boron chain.
KW  - diboranes
KW  - diborenes
KW  - N-heterocyclic carbenes
KW  - boron chains
KW  - pi-conjugation
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-167977
N1  - This is the pre-peer reviewed version of the following article: A. Hermann, J. Cid, J. D. Mattock, R. D. Dewhurst, I. Krummenacher, A. Vargas, M. J. Ingleson, H. Braunschweig, Angew. Chem. Int. Ed. 2018, 57, 10091, which has been published in final form at https://doi.org/10.1002/anie.201805394. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.
ER  - 
TY  - INPR
A1  - Böhnke, Julian
A1  - Arrowsmith, Merle
A1  - Braunschweig, Holger
T1  - Activation of a Zerovalent Diboron Compound by Desymmetrization
T2  - Journal of the American Chemical Society
N2  - The desymmetrization of the cyclic (alkyl)(amino)carbene-supported diboracumulene, B\(_2\)(cAAC\(^{Me}\))\(_2\) (cAAC\(^{Me}\) = 1- (2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) by mono-adduct formation with IMe\(^{Me}\) (1,3-dimethylimidazol-2-ylidene) yields the zerovalent sp-sp\(^2\) diboron compound B\(_2\)(cAAC\(^{Me}\))\(_2\)(IMe\(^{Me}\)), which provides a versatile platform for the synthesis of novel symmetrical and unsymmetrical zerovalent sp\(^2\)-sp\(^2\) diboron compounds by adduct formation with IMe\(^{Me}\) and CO, respectively. Furthermore, B\(_2\)(cAAC\(^{Me}\))\(_2\)(IMe\(^{Me}\)) displays enhanced reactivity compared to its symmetrical precursor, undergoing spontaneous intramolecular C-H activation and facile twofold hydrogenation, the latter resulting in B-B bond cleavage and the formation of the mixed-base parent borylene, (cAAC\(^{Me}\))(IMe\(^{Me}\))BH.
KW  - diboryne
KW  - boron
KW  - carbenes
KW  - low-valent main group chemistry
KW  - erovalent diboron compounds
KW  - desymmetrization
KW  - bond activation
KW  - hydrogenation
KW  - borylene
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-167983
N1  - This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in Journal of the American Chemical Society, copyright © American Chemical Society after peer review. To access the final edited and published work see https://doi.org/10.1021/jacs.8b06930
(Julian Böhnke, Merle Arrowsmith, and Holger Braunschweig: Reactivity Enhancement of a Zerovalent Diboron Compound by Desymmetrization, Journal of the American Chemical Society 2018, 140, (32), 10368-10373. DOI: 10.1021/jacs.8b06930)
ER  - 
TY  - INPR
A1  - Arrowsmith, Merle
A1  - Braunschweig, Holger
A1  - Stennett, Tom
T1  - Formation and Reactivity of Electron-Precise B–B Single and Multiple Bonds
T2  - Angewandte Chemie, International Edition
N2  - Recent years have seen rapid advances in the chemistry of small molecules containing electron-precise boron-boron bonds. This review provides an overview of the latest methods for the controlled synthesis of B–B single and multiple bonds as well as the ever-expanding range of reactivity displayed by the latter.
KW  - Boron
KW  - Main-group chemistry
KW  - Multiple bonding
KW  - Organoboron chemistry
KW  - Transition metals
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-145631
N1  - This is the pre-peer reviewed version of the following article: Angew.Chem. Int. Ed. 2017, 56,96–115, which has been published in final form at 10.1002/anie.201610072. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
N1  - Submitted Version
VL  - 56
IS  - 1
ER  - 
TY  - JOUR
A1  - Brückner, Tobias
A1  - Dewhurst, Rian D.
A1  - Dellermann, Theresa
A1  - Müller, Marcel
A1  - Braunschweig, Holger
T1  - Mild synthesis of diboryldiborenes by diboration of B–B triple bonds
JF  - Chemical Science
N2  - A set of diboryldiborenes are prepared by the mild, catalyst-free, room-temperature diboration of the B–B triple bonds of doubly base-stabilized diborynes. Two of the product diboryldiborenes are found to be air- and water-stable in the solid state, an effect that is attributed to their high crystallinity and extreme insolubility in a wide range of solvents.
KW  - boron
KW  - diborenes
KW  - diboration
KW  - triple bonds
KW  - diborynes
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-186306
VL  - 10
ER  - 
TY  - INPR
A1  - Légaré, Marc-André
A1  - Pranckevicius, Conor
A1  - Braunschweig, Holger
T1  - Metallomimetic Chemistry of Boron
T2  - Chemical Reviews
N2  - The study of main-group molecules that behave and react similarly to transition-metal (TM) complexes has attracted significant interest in recent decades. Most notably, the attractive idea of replacing the all-too-often rare and costly metals from catalysis has motivated efforts to develop main-group-element-mediated reactions. Main-group elements, however, lack the electronic flexibility of TM complexes that arises from combinations of empty and filled d orbitals and that seem ideally suited to bind and activate many substrates. In this review, we look at boron, an element that despite its nonmetal nature, low atomic weight, and relative redox staticity has achieved great milestones in terms of TM-like reactivity. We show how in interelement cooperative systems, diboron molecules, and hypovalent complexes the fifth element can acquire a truly metallomimetic character. As we discuss, this character is powerfully demonstrated by the reactivity of boron-based molecules with H2, CO, alkynes, alkenes and even with N2.
KW  - boron
KW  - small-molecule activation
KW  - catalysis
KW  - low-valent main group chemistry
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-186317
N1  - This document is the unedited Author’sv ersion of a Submitted Work that was subsequently accepted for publication in Chemical Reviews,copyright ©American Chemical Society after peer review. To access the final edited and published work see https://doi.org/10.1021/acs.chemrev.8b00561.
ER  - 
TY  - INPR
A1  - Brückner, Tobias
A1  - Stennett, Tom E.
A1  - Heß, Merlin
A1  - Braunschweig, Holger
T1  - Single and Double Hydroboration of B-B Triple Bonds and Conver- gent Routes to a Cationic Tetraborane
T2  - Journal of the American Chemical Society
N2  - A compound with a boron-boron triple bond is shown to undergo stepwise hydroboration reactions with catecholborane to yield an unsymmetrical hydro(boryl)diborene and a 2,3-dihydrotetraborane. Abstraction of H– from the latter compound produces an unusual cationic, planar tetraborane with a hydrogen atom bridging the central B2 moiety. Spectroscopic and crystallographic data and DFT calculations support a ‘protonated diborene’ structure for this compound, which can also be accessed via direct protonation of the corresponding diborene.
KW  - boron
KW  - multiple bonding
KW  - hydroboration
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-188632
N1  - This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in Journal of the American Chemical Society, copyright © American Chemical Society after peer review. To access the final edited and published work see https://doi.org/10.1021/jacs.9b07991.
ER  - 
TY  - INPR
A1  - Muessig, Jonas H.
A1  - Thaler, Melanie
A1  - Dewhurst, Rian D.
A1  - Paprocki, Valerie
A1  - Seufert, Jens
A1  - Mattock, James D.
A1  - Vargas, Alfredo
A1  - Braunschweig, Holger
T1  - Phosphine-Stabilized Diiododiborenes: Isolable Diborenes with Six Labile Bonds
T2  - Angewandte Chemie, International Edition
N2  - The lability of B=B, B-P and B-halide bonds is combined in the syntheses of the first diiododiborenes. In a series of reactivity tests, these diiododiborenes demonstrate cleavage of all six of their central bonds in different ways, leading to products of B=B hydrogenation and dihalogenation as well as halide exchange.
KW  - boron
KW  - low-valent main-group species
KW  - iodine
KW  - multiple bonding
KW  - 1,2-additions
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-178608
N1  - This is the pre-peer reviewed version of the following article: J. H. Muessig, M. Thaler, R. D. Dewhurst, V. Paprocki, J. Seufert, J. D. Mattock, A. Vargas, H. Braunschweig, Angew. Chem. Int. Ed. 2019, 58, 4405, which has been published in final form at https://doi.org/10.1002/anie.201814230. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.
ER  - 
TY  - INPR
A1  - Stennett, Tom
A1  - Mattock, James
A1  - Pentecost, Leanne
A1  - Vargas, Alfredo
A1  - Braunschweig, Holger
T1  - Chelated Diborenes and their Inverse-Electron-Demand Diels- Alder Reactions with Dienes
T2  - Angewandte Chemie, International Edition
N2  - A doubly base-stabilized diborane based on a benzylphosphine linker was prepared by a salt elimination reaction between 2-LiC\(_6\)H\(_4\)CH\(_2\)PCy\(_2\).Et\(_2\)O and B\(_2\)Br\(_4\). This compound was reduced with KC8 to its corresponding diborene, with the benzylphosphine forming a five-membered chelate. The diborene reacts with butadiene, 2-trimethylsiloxy-1,3-butadiene and isoprene to form 4,5-diboracyclohexenes, which interconvert between their 1,1- (geminal) and 1,2- (vicinal) chelated isomers. The 1,1-chelated diborene undergoes a halide-catalysed isomerisation into its thermodynamically favoured 1,2-isomer, which undergoes Diels-Alder reactions more slowly than the kinetic product.
KW  - boron
KW  - cycloaddition
KW  - DFT calculations
KW  - chelates
KW  - low-valent compounds
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-178268
N1  - This is the pre-peer reviewed version of the following article: T. E. Stennett, J. D. Mattock, L. Pentecost, A. Vargas, H. Braunschweig, Angew. Chem. Int. Ed. 2018, 57, 15276., which has been published in final form at https://doi.org/10.1002/anie.201809217. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.
ER  - 
TY  - JOUR
A1  - Ansell, Melvyn B.
A1  - Kostakis, George E.
A1  - Braunschweig, Holger
A1  - Navarro, Oscar
A1  - Spencer, John
T1  - Synthesis of functionalized hydrazines: facile homogeneous (N-heterocyclic carbene)-palladium(0)-catalyzed diboration and silaboration of azobenzenes
JF  - Advanced Synthesis & Catalysis
N2  - The bis(N-heterocyclic carbene)(diphenylacetylene)palladium complex Pd(ITMe)\(_2\)(PhCCPh)] (ITMe=1,3,4,5-tetramethylimidazol-2-ylidene) acts as a highly active pre-catalyst in the diboration and silaboration of azobenzenes to synthesize a series of novel functionalized hydrazines. The reactions proceed using commercially available diboranes and silaboranes under mild reaction conditions.
KW  - Palladium-catalyzed silaboration
KW  - B-B bond
KW  - molecular-structure
KW  - terminal alkynes
KW  - crystal-structure
KW  - alkenes
KW  - complexes
KW  - mechanism
KW  - boron
KW  - design
KW  - azobenzenes
KW  - dilaboration
KW  - N-heterocyclic carbenes
KW  - palladium
KW  - silaboration
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-186582
VL  - 358
IS  - 23
ER  - 
TY  - INPR
A1  - Stennett, Tom
A1  - Bertermann, Rüdiger
A1  - Braunschweig, Holger
T1  - Construction of Linear and Branched Tetraboranes via 1,1- and 1,2-Diboration of Diborenes
T2  - Angewandte Chemie, International Edition
N2  - Sterically unencumbered diborenes based on a benzylphosphine chelate undergo diboration reactions with bis(catecholato)diboron in the absence of a catalyst to yield tetraboranes. The symmetrical diborenes studied undergo 1,2- diborations, whereas an unsymmetrical derivative was found to yield a triborylborane-phosphine adduct as the result of a formal 1,1-diboration. A related borylborylene compound also underwent a 1,2-diboration to produce a borylene-borane adduct.
KW  - boron
KW  - diboration
KW  - chain structures
KW  - low-valent compounds
KW  - isomers
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-178276
N1  - This is the pre-peer reviewed version of the following article: T. E. Stennett, R. Bertermann, H. Braunschweig, Angew. Chem. Int. Ed. 2018, 57, 15896., which has been published in final form at https://doi.org/10.1002/anie.201809976. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.
ER  - 
TY  - INPR
A1  - Brückner, Tobias
A1  - Arrowsmith, Merle
A1  - Heß, Merlin
A1  - Hammond, Kai
A1  - Müller, Marcel
A1  - Braunschweig, Holger
T1  - Synthesis of fused B,N-heterocycles by alkyne cleavage, NHC ring-expansion and C-H activation at a diboryne
T2  - Chemical Communications
N2  - The addition of alkynes to a staturated N-heterocyclic carbene (NHC)-supported diboryne results in spontaneous cycloaddition, with complete B≡B and C≡C triple bond cleavage, NHC ring- expansion and activation of a variety of C-H bonds, leading to the formation of complex mixtures of fused B,N-heterocycles.
KW  - heterocycles
KW  - alkynes
KW  - boron
KW  - carbenes
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-184899
N1  - This is the pre-peer reviewed version of the following article: Chem. Commun., 2019,55, 6700-6703, which has been published in final form at doi:10.1039/C9CC02657F
ER  - 
TY  - INPR
A1  - Stennett, Tom E.
A1  - Bissinger, Philipp
A1  - Griesbeck, Stefanie
A1  - Ullrich, Stefan
A1  - Krummenacher, Ivo
A1  - Auth, Michael
A1  - Sperlich, Andreas
A1  - Stolte, Matthias
A1  - Radacki, Krzysztof
A1  - Yao, Chang-Jiang
A1  - Würthner, Frank
A1  - Steffen, Andreas
A1  - Marder, Todd B.
A1  - Braunschweig, Holger
T1  - Near-Infrared Quadrupolar Chromophores Combining Three-Coordinate Boron-Based Superdonor and Superacceptor Units
T2  - Angewandte Chemie, International Edition
N2  - In this work, two new quadrupolar A-π-D-π-A chromophores have been prepared featuring a strongly electron- donating diborene core and strongly electron-accepting dimesitylboryl F(BMes2) and bis(2,4,6-tris(trifluoromethyl)phenyl)boryl (BMes2) end groups. Analysis of the compounds by NMR spectroscopy, X-ray crystallography, cyclic voltammetry and UV-vis-NIR absorption and emission spectroscopy indicated that the compounds possess extended conjugated π-systems spanning their B4C8 cores. The combination of exceptionally potent π-donor (diborene) and π- acceptor (diarylboryl) groups, both based on trigonal boron, leads to very small HOMO-LUMO gaps, resulting in strong absorption in the near-IR region with maxima in THF at 840 and 1092 nm, respectively, and very high extinction coefficients of ca. 120,000 M-1cm-1. Both molecules also display weak near-IR fluorescence with small Stokes shifts.
KW  - boron
KW  - near-IR chromophores
KW  - conjugation
KW  - low-valent compounds
KW  - synthesis
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-180391
N1  - This is the pre-peer reviewed version of the following article: T. E. Stennett, P. Bissinger, S. Griesbeck, S. Ullrich, I. Krummenacher, M. Auth, A. Sperlich, M. Stolte, K. Radacki, C.-J. Yao, F. Wuerthner, A. Steffen, T. B. Marder, H. Braunschweig, Angew. Chem. Int. Ed. 2019, 58, 6449. , which has been published in final form at  https://doi.org/10.1002/anie.201900889. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.
ER  - 
TY  - INPR
A1  - Arrowsmith, Merle
A1  - Dömling, Michael
A1  - Schmidt, Uwe
A1  - Werner, Luis
A1  - Castro, Abril C.
A1  - Jiménez-Halla, J. Oscar C.
A1  - Müssig, Jonas
A1  - Prieschl, Dominic
A1  - Braunschweig, Holger
T1  - Spontaneous trans‐Selective Transfer Hydrogenation of Apolar B=B Double Bonds
T2  - Angewandte Chemie, International Edition
N2  - The transfer hydrogenation of NHC-supported diborenes with dimethylamine borane proceeds with high selectivity for the trans-1,2-dihydrodiboranes(6). DFT calculations suggest a stepwise proton-first-hydride-second reaction mechanism via an intermediate μ-hydrodiboronium dimethylaminoborate ion pair.
KW  - transfer hydrogenation
KW  - diborene
KW  - amine borane dehydrocoupling
KW  - diboranes
KW  - DFT mechanism
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-184874
N1  - This is the pre-peer reviewed version of the following article: M. Dömling, M. Arrowsmith, U. Schmidt, L. Werner, A. C. Castro, J. O. C. Jiménez-Halla, R. Bertermann, J. Müssig, D. Prieschl, H. Braunschweig, Angew. Chem. Int. Ed. 2019, 58, 9782. doi:10.1002/anie.201902656, which has been published in final form at  https://doi.org/10.1002/anie.201902656. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.
ER  - 
TY  - JOUR
A1  - Braunschweig, Holger
A1  - Ewing, William C.
A1  - Ghosh, Sundargopal
A1  - Kramer, Thomas
A1  - Mattock, James D.
A1  - Östreicher, Sebastian
A1  - Vargas, Alfredo
A1  - Werner, Christine
T1  - Trimetallaborides as starting points for the syntheses of large metal-rich molecular borides and clusters
JF  - Chemical Science
N2  - Treatment of an anionic dimanganaborylene complex ([{Cp(CO)\(_2\)Mn}\(_2\)B]\(^-\)) with coinage metal cations stabilized by a very weakly coordinating Lewis base (SMe\(_2\)) led to the coordination of the incoming metal and subsequent displacement of dimethylsulfide in the formation of hexametalladiborides featuring planar four-membered M\(_2\)B\(_2\) cores (M = Cu, Au) comparable to transition metal clusters constructed around four-membered rings composed solely of coinage metals. The analogies between compounds consisting of B\(_2\)M\(_2\) units and M\(_4\) (M = Cu, Au) units speak to the often overlooked metalloid nature of boron. Treatment of one of these compounds (M = Cu) with a Lewis-basic metal fragment (Pt(PCy\(_3\))\(_2\)) led to the formation of a tetrametallaboride featuring two manganese, one copper and one platinum atom, all bound to boron in a geometry not yet seen for this kind of compound. Computational examination suggests that this geometry is the result of d\(^{10}\)-d\(^{10}\) dispersion interactions between the copper and platinum fragments.
KW  - anionic dimetalloborylene complexes
KW  - trimetallaborides
KW  - tetrametallaborides
KW  - Boron
KW  - metallaboranes
KW  - crystal structure
KW  - metal borylene complexes
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-191511
VL  - 7
IS  - 1
ER  - 
TY  - INPR
A1  - Hermann, Alexander
A1  - Arrowsmith, Merle
A1  - Trujillo-Gonzalez, Daniel
A1  - Jiménez-Halla, J. Oscar C.
A1  - Vargas, Alfredo
A1  - Braunschweig, Holger
T1  - Trapping of a Borirane Intermediate in the Reductive Coupling of an Arylborane to a Diborene
T2  - Journal of the American Chemical Society
N2  - The reductive coupling of an NHC-stabilized aryldibromoborane yields a mixture of trans- and cis-diborenes in which the aryl groups are coplanar with the diborene core. Under dilute reduction conditions two diastereomers of a borirane-borane intermediate are isolated, which upon further reduction give rise to the aforementioned diborene mixture. DFT calculations suggest a mechanism proceeding via nucleophilic attack of a dicoordinate borylene intermediate on the aryl ring and subsequent intramolecular B-B bond formation.
KW  - boron
KW  - reactive intermediates
KW  - reductive coupling
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-203140
N1  - This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in Journal of the American Chemical Society, copyright © American Chemical Society after peer review. To access the final edited and published work see https://doi.org/10.1021/jacs.0c02306
ER  - 
TY  - JOUR
A1  - Braunschweig, Holger
A1  - Krummenacher, Ivo
A1  - Mailänder, Lisa
A1  - Pentecost, Leanne
A1  - Vargas, Alfredo
T1  - Formation of a stable radical by oxidation of a tetraorganoborate
JF  - Chemical Communications
N2  - Herein, we describe the selective formation of a stable neutral spiroborate radical by one-electron oxidation of the corresponding tetraorganoborate salt Li[B(C\(_4\)Ph\(_4\))\(_2\)], formally containing a tetrahedral borate centre and a s-cis-butadiene radical cation as the spin-bearing site. Spectroscopic and computational methods have been used to determine the spin distribution and the chromism observed in the solid state.
KW  - tetraorganoborate salt
KW  - spiroborates
KW  - one-electron oxidation
KW  - spin distribution
KW  - chromism
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-191321
VL  - 52
IS  - 43
ER  - 
TY  - INPR
A1  - Wang, Sunewang Rixin
A1  - Arrowsmith, Merle
A1  - Braunschweig, Holger
A1  - Dewhurst, Rian
A1  - Dömling, Michael
A1  - Mattock, James
A1  - Pranckevicius, Conor
A1  - Vargas, Alfredo
T1  - Monomeric 16-Electron π-Diborene Complexes of Zn(II) and Cd(II)
T2  - Journal of the American Chemical Society
N2  - Despite the prevalence of stable π-complexes of most d\(^{10}\) metals, such as Cu(I) and Ni(0), with ethylene and other olefins, complexation of d\(^{10}\) Zn(II) to simple olefins is too weak to form isolable complexes due to the metal ion's limited capacity for π-backdonation. By employing more strongly donating π- ligands, namely neutral diborenes with a high-lying π(B=B) or- bital, monomeric 16-electron M(II)-diborene (M = Zn, Cd) π- complexes were synthesized in good yields. Metal–B2 π- interactions in both the solid and solution state were confirmed by single-crystal X-ray analyses and their solution NMR and UV-vis absorption spectroscopy, respectively. The M(II) centers adopt a trigonal planar geometry and interact almost symmetrically with both boron atoms. The MB2 planes significantly twist out of the MX\(_2\) planes about the M-centroid(B–B) vector, with angles rang- ing from 47.0° to 85.5°, depending on the steric interactions be- tween the diborene ligand and the MX\(_2\) fragment.
KW  - boron
KW  - transition metal complex
KW  - diborene
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-153058
N1  - This is the pre-peer reviewed version of the following article: Journal of the American Chemical Society, 2017, 139 (31), pp 10661–10664, which has been published in final form at doi:10.1021/jacs.7b06644.
ER  - 
TY  - INPR
A1  - Englert, Lukas
A1  - Stoy, Andreas
A1  - Arrowsmith, Merle
A1  - Müssig, Jonas H.
A1  - Thaler, Melanie
A1  - Deißenberger, Andrea
A1  - Häfner, Alena
A1  - Böhnke, Julian
A1  - Hupp, Florian
A1  - Seufert, Jens
A1  - Mies, Jan
A1  - Damme, Alexander
A1  - Dellermann, Theresa
A1  - Hammond, Kai
A1  - Kupfer, Thomas
A1  - Radacki, Krzysztof
A1  - Thiess, Torsten
A1  - Braunschweig, Holger
T1  - Stable Lewis Base Adducts of Tetrahalodiboranes: Synthetic Methods and Structural Diversity
T2  - Chemistry - A European Journal
N2  - A series of 22 new bis(phosphine), bis(carbene) and bis(isonitrile) tetrahalodiborane adducts has been synthesized, either by direct adduct formation with highly sensitive B2X4 precursors (X = Cl, Br, I) or by ligand exchange at stable B2X4(SMe2)2 precursors (X = Cl, Br) with labile dimethylsulfide ligands. The isolated compounds have been fully characterized using NMR spectroscopic, (C,H,N)- elemental and, for 20 of these compounds, X-ray crystallographic analysis, revealing an unexpected variation in the bonding motifs. Besides the classical B2X4L2 diborane(6) adducts, some of the more sterically demanding carbene ligands induce a halide displacement leading to the first halide-bridged monocationic diboron species, [B2X3L2]A (A = BCl4, Br, I). Furthermore, low-temperature 1:1 reactions of B2Cl4 with sterically demanding N-heterocyclic carbenes led to the formation of kinetically unstable mono-adducts, one of which was structurally characterized. A comparison of the NMR and structural data of new and literature-known bis-adducts shows several trends pertaining to the nature of the halides and the stereoelectronic properties of the Lewis bases employed.
KW  - diborane(6)
KW  - Lewis-base adducts
KW  - ligand exchange
KW  - crystallography
KW  - NMR spectroscopy
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-184888
N1  - This is the pre-peer reviewed version of the following article: L. Englert, A. Stoy, M. Arrowsmith, J. H. Muessig, M. Thaler, A. Deißenberger, A. Häfner, J. Böhnke, F. Hupp, J. Seufert, J. Mies, A. Damme, T. Dellermann, K. Hammond, T. Kupfer, K. Radacki, T. Thiess, H. Braunschweig, Chem. Eur. J. 2019, 25, 8612. https://doi.org/10.1002/chem.201901437, which has been published in final form at https://doi.org/10.1002/chem.201901437. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.
ER  - 
TY  - JOUR
A1  - Braunschweig, Holger
A1  - Arnold, Thomas
A1  - Gruss, Katrin
T1  - cyclo-Tri-mu-oxido-tris{[(eta 5,eta 5)-1,2-bis(cyclopentadienyl)-1,1,2,2-tetramethyldisilane]zirconium(IV)}: atrimeric disila-bridged oxidozirconocene
N2  - no abstract available
KW  - Chemie
KW  - single-crystal X-ray study
KW  - T = 174 K
KW  - R factor = 0.027
KW  - wR factor = 0.069
KW  - data-to-parameter ratio = 23.6.
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-74737
ER  - 
TY  - JOUR
A1  - Braunschweig, Holger
A1  - Dewhurst, Rian D.
A1  - Schwab, Katrin
A1  - Wagner, Katharina
T1  - {N ',N ''-Bis[2,6-bis(1-methylethyl)phenyl]-N,N-dimethylguanidinato-kappa N-2 ',N ''}dibromidoborane
N2  - In the molecular structure of the title compound, C27H40N3BBr2, the B atom is connected to two bromide substituents and a guanidinate scaffold, forming a four– membered ring. An aryl group is connected to each N atom in the ring that contains two isopropyl groups in positions 2 and 6.
KW  - Anorganische Chemie
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-67622
ER  - 
TY  - JOUR
A1  - Braunschweig, Holger
A1  - Damme, Alexander
T1  - 1,2-Bis(dimethylamino)-1,2-bis(2,4,6-triisopropylphenyl)diborane(4)
N2  - In the molecular structure of the title compound, C34H58B2N2, each B atom of the diborane(4) is connected to one dimethylamino group and one Tip ligand (Tip = 2,4,6-triisopropylphenyl). These findings indicate that the increased steric demand of the Tip groups exerts influence solely on the B—B separation but not on the overall geometry of the title compound.
KW  - Anorganische Chemie
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-67639
ER  - 
TY  - JOUR
A1  - Arnold, Nicole
A1  - Braunschweig, Holger
A1  - Damme, Alexander
T1  - Bis(μ-diisopropyl-phosphanido-\(κ^2\)P:P)bis-[hydrido(triisopropyl-phosphane-κP)platinum(II)]
JF  - Acta crystallographica. Section E, Structure reports online
N2  - In the centrosymmetric molecular structure of the title compound \([Pt_2(C_6H_{14}P)_2H_2)(C_9H_{21}P)_2]\), each \(Pt^{II}\) atom is bound on one side to a phosphane ligand \((PiPr_3)\) and a hydrido ligand. On the other side, it is bound to two phosphanide ligands \((μ-PiPr_2)\), which engage a bridging position between the two \(Pt^{II}\) atoms, forming a distorted square-planar structure motif. The PtPt distance is 3.6755(2)Å. A comparable molecular structure was observed for bis-(μ-di-tert-butyl-phosphanido)bis-[hydrido(triethyl-phosphane)platinum(II)] [Itazaki et al. (2004 ). Organometallics, 23, 1610-1621].
KW  - data-to-parameter ratio = 22.3
KW  - mean σ(C–C) = 0.004 Å
KW  - single-crystal X-ray study
KW  - T = 100 K
KW  - R factor = 0.018
KW  - wR factor = 0.038
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-123723
VL  - E68
ER  - 
TY  - JOUR
A1  - Braunschweig, Holger
A1  - Kramer, T.
T1  - Crystal structure of μ-1κC:2(\(η^2\))-carbonyl-carbonyl-1κC-chlorido-2κCl-μ-chloridoborylene-1:2\(κ^2\) B:B-[1(\(η^5\))-pentamethylcyclopentadienyl](tricyclohexylphosphane-2κP)iron(II)platinum(II) benzene monosolvate
N2  - In the mol­ecular structure of the dinuclear title compound \([η^5-(C_5(CH_3)_5)(CO)Fe{(μ-BCl)(μ-CO)}PtCl(P(C_6H_{11})_3)]·C_6H_6\), the two metal atoms, iron(II) and platinum(II), are bridged by one carbonyl (μ-CO) and one chlorido­borylene ligand (μ-BCl). The \(Pt^{II}\) atom is additionally bound to a chloride ligand situated trans to the bridging borylene, and a tri­cyclo­hexyl­phosphane ligand \((PCy_3)\) trans to the carbonyl ligand, forming a distorted square-planar structural motif at the \(Pt^{II}\) atom. The \(Fe_{II}\) atom is bound to a penta­methyl­cyclo­penta­dienyl ligand \([η^5-C_5(CH_3)_5]\) and one carbonyl ligand (CO), forming a piano-stool structure. Additionally, one benzene solvent mol­ecule is incorporated into the crystal structure, positioned staggered relative to the penta­methyl­cyclo­penta­dienyl ligand at the \(Fe^{II}\) atom, with a centroid–centroid separation of 3.630 (2) Å.
KW  - platinum
KW  - oxidative addition
KW  - borylene
KW  - heterodinuclear compound
KW  - crystal structure
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-120120
VL  - 70
IS  - 11
ER  - 
TY  - JOUR
A1  - Stennett, Tom E.
A1  - Jayaraman, Arumugam
A1  - Brückner, Tobias
A1  - Schneider, Lea
A1  - Braunschweig, Holger
T1  - Hydrophosphination of boron–boron multiple bonds
JF  - Chemical Science
N2  - Five compounds containing boron–boron multiple bonds are shown to undergo hydrophosphination reactions with diphenylphosphine in the absence of a catalyst. With diborenes, the products obtained are highly dependent on the substitution pattern at the boron atoms, with both 1,1- and 1,2- hydrophosphinations observed. With a symmetrical diboryne, 1,2-hydrophosphination yields a hydro(phosphino)diborene. The different mechanistic pathways for the hydrophosphination of diborenes are rationalised with the aid of density functional theory calculations.
KW  - boron
KW  - diborenes
KW  - diborynes
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-240681
VL  - 11
ER  - 
TY  - JOUR
A1  - Arrowsmith, Merle
A1  - Böhnke, Julian
A1  - Braunschweig, Holger
A1  - Celik, Mehmet
A1  - Dellermann, Theresa
A1  - Hammond, Kai
T1  - Uncatalyzed Hydrogenation of First-Row Main Group Multiple Bonds
JF  - Chemistry, A European Journal
N2  - Room temperature hydrogenation of an SIDep-stabilized diboryne (SIDep = 1,3-bis(diethylphenyl)-4,5-dihydroimidazol-2-ylidene) and a CAAC-supported diboracumulene (CAAC = 1-(2,6- diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) provided the first selective route to the corresponding 1,2-dihydrodiborenes. DFT calculations showed an overall exothermic (ΔG = 19.4 kcal mol\(^{-1}\) two-step asynchronous H\(_2\) addition mechanism proceeding via a bridging hydride.
KW  - diborenes
KW  - carbenes
KW  - hydrogenation
KW  - main-group chemistry
KW  - reaction mechanism
KW  - Diborane
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-139364
N1  - This is the peer reviewed version of the following article: Chemistry, A European Journal, 2016, 22, 17169–17172, which has been published in final form at 10.1002/chem.201604094. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
VL  - 22
IS  - 48
SP  - 17169
EP  - 17172
ER  - 
TY  - JOUR
A1  - Arrowsmith, Merle
A1  - Böhnke, Julian
A1  - Braunschweig, Holger
A1  - Celik, Mehmet
A1  - Claes, Christina
A1  - Ewing, William
A1  - Krummenacher, Ivo
A1  - Lubitz, Katharina
A1  - Schneider, Christoph
T1  - Neutral Diboron Analogues of Archetypal Aromatic Species by Spontaneous Cycloaddition
JF  - Angewandte Chemie, International Edition
N2  - Among the numerous routes organic chemists have developed to synthesize benzene derivatives and heteroaro- matic compounds, transition-metal-catalyzed cycloaddition reactions are the most elegant. In contrast, cycloaddition reactions of heavier alkene and alkyne analogues, though limited in scope, proceed uncatalyzed. In this work we present the first spontaneous cycloaddition reactions of lighter alkene and alkyne analogues. Selective addition of unactivated alkynes to boron–boron multiple bonds under ambient con- ditions yielded diborocarbon equivalents of simple aromatic hydrocarbons, including the first neutral 6 π-aromatic dibora- benzene compound, a 2  π-aromatic triplet biradical 1,3-dibor- ete, and a phosphine-stabilized 2  π-homoaromatic 1,3-dihydro- 1,3-diborete. DFT calculations suggest that all three com- pounds are aromatic and show frontier molecular orbitals matching those of the related aromatic hydrocarbons, C\(_6\)H\(_6\) and C\(_4\)H\(_4\)\(^{2+}\), and homoaromatic C\(_4\)H\(_5\)\(^+\).
KW  - Aromaticity
KW  - Biradicals
KW  - Boron
KW  - Cycloaddition
KW  - Multiple bonds
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-138226
N1  - This is the peer reviewed version of the following article: Angew. Chem. Int. Ed. 2016, 55, 11271–11275, which has been published in final form at 10.1002/anie.201602384. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
VL  - 55
ER  - 
TY  - JOUR
A1  - Braunschweig, Holger
A1  - Constantinidis, Philipp
A1  - Dellermann, Theresa
A1  - Ewing, William
A1  - Fischer, Ingo
A1  - Hess, Merlin
A1  - Knight, Fergus
A1  - Rempel, Anna
A1  - Schneider, Christoph
A1  - Ullrich, Stefan
A1  - Vargas, Alfredo
A1  - Woolins, Derek
T1  - Highly Strained Heterocycles Constructed from Boron–Boron Multiple Bonds and Heavy Chalcogens
JF  - Angewandte Chemie, International Edition
N2  - The reactions of a diborene with elemental selenium or tellurium are shown to afford a diboraselenirane or diboratellurirane, respectively. These reactions are reminiscent of the sequestration of subvalent oxygen and nitrogen in the formation of oxiranes and aziridines; however, such reactivity is not known between alkenes and the heavy chalcogens. Although carbon is too electronegative to affect the reduction of elements with lower relative electronegativity, the highly reducing nature of the B B double bond enables reactions with Se0 and Te0. The capacity of multiple bonds between boron atoms to donate electron density is highlighted in reactions where diborynes behave as nucleophiles, attacking one of the two Te atoms of diaryltellurides, forming salts consisting of diboratellurenium cations and aryltelluride anions.
KW  - Boron
KW  - Heterocycles
KW  - Multiple bonds
KW  - Selenium
KW  - Tellurium
KW  - Bor
KW  - Heterocyclische Verbindungen
KW  - Selen
KW  - Tellur
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-138237
N1  - This is the peer reviewed version of the following article: Angew. Chem. Int. Ed. 2016, 55, 5606–5609, which has been published in final form at 10.1002/anie.201601691. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
N1  - Accepted Version
VL  - 55
IS  - 18
SP  - 5606
EP  - 5609
ER  - 
TY  - JOUR
A1  - Arnold, Thomas
A1  - Braunschweig, Holger
A1  - Gruss, Katrin
T1  - cyclo-Tri-mu-oxido-tris{[(eta 5,eta 5)-1,2-bis(cyclopentadienyl)-1,1,2,2-tetramethyldisilane]zirconium(IV)}: a trimeric disila-bridged oxidozirconocene
JF  - Acta Crystallographica Section E: metal-organic compounds
N2  - The title compound, [Zr(3)(C(14)H(20)Si(2))(3)O(3)], consists of three disila-bridged zirconocene units, which are connected via an oxide ligand, forming a nearly planar six-membered ring with a maximum displacement of 0.0191 (8) A. The compound was isolated as a by-product from a mixture of [(C(5)H(4)SiMe(2))(2)ZrCl(2)] and Li[AlH(4)] in Et(2)O.
KW  - Kristallographie
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-134802
VL  - 67
ER  - 
TY  - INPR
A1  - Schmidt, Uwe
A1  - Fantuzzi, Felipe
A1  - Arrowsmith, Merle
A1  - Hermann, Alexander
A1  - Prieschl, Dominic
A1  - Rempel, Anna
A1  - Engels, Bernd
A1  - Braunschweig, Holger
T1  - Tuneable reduction of cymantrenylboranes to diborenes or borylene-derived boratafulvenes
T2  - Chemical Communications
N2  - Whereas the reduction of N-heterocyclic carbene (NHC)-stabilised cymantrenyldibromoboranes, (NHC)BBr\(_2\)Cym, in benzene results in formation of the corresponding diborenes (NHC)\(_2\)B\(_2\)Cym\(_2\), a change of solvent to THF yields a borylene of the form (NHC)\(_2\)BCym, stabilised through its boratafulvene resonance form.
KW  - Borylene
KW  - Diborene
KW  - Boranes
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-222149
ER  -