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  - 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  - Schmidt, Paul
A1  - Fantuzzi, Felipe
A1  - Klopf, Jonas
A1  - Schröder, Niklas B.
A1  - Dewhurst, Rian D.
A1  - Braunschweig, Holger
A1  - Engel, Volker
A1  - Engels, Bernd
T1  - Twisting versus delocalization in CAAC- and NHC-stabilized boron-based biradicals: the roles of sterics and electronics
JF  - Chemistry - A European Journal
N2  - Twisted boron-based biradicals featuring unsaturated C\(_2\)R\(_2\) (R=Et, Me) bridges and stabilization by cyclic (alkyl)(amino)carbenes (CAACs) were recently prepared. These species show remarkable geometrical and electronic differences with respect to their unbridged counterparts. Herein, a thorough computational investigation on the origin of their distinct electrostructural properties is performed. It is shown that steric effects are mostly responsible for the preference for twisted over planar structures. The ground-state multiplicity of the twisted structure is modulated by the σ framework of the bridge, and different R groups lead to distinct multiplicities. In line with the experimental data, a planar structure driven by delocalization effects is observed as global minimum for R=H. The synthetic elusiveness of C\(_2\)R\(_2\)-bridged systems featuring N-heterocyclic carbenes (NHCs) was also investigated. These results could contribute to the engineering of novel main group biradicals.
KW  - chemistry
KW  - radicals
KW  - ab initio calculations
KW  - boron
KW  - carbene ligands
KW  - density functional calculations
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256636
VL  - 27
IS  - 16
ER  - 
TY  - JOUR
A1  - Saalfrank, Christian
A1  - Fantuzzi, Felipe
A1  - Kupfer, Thomas
A1  - Ritschel, Benedikt
A1  - Hammond, Kai
A1  - Krummenacher, Ivo
A1  - Bertermann, Rüdiger
A1  - Wirthensohn, Raphael
A1  - Finze, Maik
A1  - Schmid, Paul
A1  - Engel, Volker
A1  - Engels, Bernd
A1  - Braunschweig, Holger
T1  - cAAC‐Stabilized 9,10‐diboraanthracenes—Acenes with Open‐Shell Singlet Biradical Ground States
JF  - Angewandte Chemie International Edition
N2  - Narrow HOMO–LUMO gaps and high charge‐carrier mobilities make larger acenes potentially high‐efficient materials for organic electronic applications. The performance of such molecules was shown to significantly increase with increasing number of fused benzene rings. Bulk quantities, however, can only be obtained reliably for acenes up to heptacene. Theoretically, (oligo)acenes and (poly)acenes are predicted to have open‐shell singlet biradical and polyradical ground states, respectively, for which experimental evidence is still scarce. We have now been able to dramatically lower the HOMO–LUMO gap of acenes without the necessity of unfavorable elongation of their conjugated π system, by incorporating two boron atoms into the anthracene skeleton. Stabilizing the boron centers with cyclic (alkyl)(amino)carbenes gives neutral 9,10‐diboraanthracenes, which are shown to feature disjointed, open‐shell singlet biradical ground states.
KW  - acenes
KW  - biradicals
KW  - bond Activation
KW  - boron
KW  - heterocycles
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-217795
VL  - 59
IS  - 43
SP  - 19338
EP  - 19343
ER  - 
TY  - JOUR
A1  - Rauch, Florian
A1  - Fuchs, Sonja
A1  - Friedrich, Alexandra
A1  - Sieh, Daniel
A1  - Krummenacher, Ivo
A1  - Braunschweig, Holger
A1  - Finze, Maik
A1  - Marder, Todd B.
T1  - Highly Stable, Readily Reducible, Fluorescent, Trifluoromethylated 9‐Borafluorenes
JF  - Chemistry – A European Journal
N2  - Three different perfluoroalkylated borafluorenes (\(^{F}\)Bf) were prepared and their electronic and photophysical properties were investigated. The systems have four trifluoromethyl moieties on the borafluorene moiety as well as two trifluoromethyl groups at the ortho positions of their exo‐aryl moieties. They differ with regard to the para substituents on their exo‐aryl moieties, being a proton \(^{F}\)Xyl\(^{F}\)Bf, \(^{F}\)Xyl: 2,6‐bis(trifluoromethyl)phenyl), a trifluoromethyl group (\(^{F}\)Mes\(^{F}\)Bf, \(^{F}\)Mes: 2,4,6‐tris(trifluoromethyl)phenyl) or a dimethylamino group (p‐NMe\(_{2}\)‐\(^{F}\)Xyl\(^{F}\)Bf, p‐NMe\(_{2}\)‐\(^{F}\)Xyl: 4‐(dimethylamino)‐2,6‐bis(trifluoromethyl)phenyl), respectively. All derivatives exhibit extraordinarily low reduction potentials, comparable to those of perylenediimides. The most electron‐deficient derivative \(^{F}\)Mes\(^{F}\)Bf was also chemically reduced and its radical anion isolated and characterized. Furthermore, all compounds exhibit very long fluorescent lifetimes of about 250 ns up to 1.6 μs; however, the underlying mechanisms responsible for this differ. The donor‐substituted derivative p‐NMe\(_{2}\)‐\(^{F}\)Xyl\(^{F}\)Bf exhibits thermally activated delayed fluorescence (TADF) from a charge‐transfer (CT) state, whereas the \(^{F}\)Mes\(^{F}\)Bf and FXylFBf borafluorenes exhibit only weakly allowed locally excited (LE) transitions due to their symmetry and low transition‐dipole moments.
KW  - borafluorenes
KW  - boron
KW  - EPR spectroscopy
KW  - fluorescence
KW  - heterocycles
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-218390
VL  - 26
IS  - 56
SP  - 12794
EP  - 12808
ER  - 
TY  - JOUR
A1  - Muessig, Jonas H.
A1  - Lisinetskaya, Polina
A1  - Dewhurst, Rian D.
A1  - Bertermann, Rüdiger
A1  - Thaler, Melanie
A1  - Mitric, Roland
A1  - Braunschweig, Holger
T1  - Tetraiododiborane(4) (B\(_2\)I\(_4\)) is a Polymer based on sp\(^3\) Boron in the Solid State
JF  - Angewandte Chemie International Edition
N2  - Herein we present the first solid‐state structures of tetraiododiborane(4) (B\(_2\)I\(_4\)), which was long believed to exist in all phases as discrete molecules with planar, tricoordinate boron atoms, like the lighter tetrahalodiboranes(4) B\(_2\)F\(_4\), B\(_2\)Cl\(_4\), and B\(_2\)Br\(_4\). Single‐crystal X‐ray diffraction, solid‐state NMR, and IR measurements indicate that B\(_2\)I\(_4\) in fact exists as two different polymeric forms in the solid state, both of which feature boron atoms in tetrahedral environments. DFT calculations are used to simulate the IR spectra of the solution and solid‐state structures, and these are compared with the experimental spectra.
KW  - boron tetraiodide
KW  - boron
KW  - density functional theory
KW  - diborane
KW  - halides
KW  - solid-state sturcture
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-209428
VL  - 59
ER  - 
TY  - JOUR
A1  - Lenczyk, Carsten
A1  - Roy, Dipak Kumar
A1  - Oberdorf, Kai
A1  - Nitsch, Jörn
A1  - Dewhurst, Rian D.
A1  - Radacki, Krzysztof
A1  - Halet, Jean-François
A1  - Marder, Todd B.
A1  - Bickelhaupt, Matthias
A1  - Braunschweig, Holger
T1  - Toward Transition‐Metal‐Templated Construction of Arylated B\(_{4}\) Chains by Dihydroborane Dehydrocoupling
JF  - Chemistry - A European Journal
N2  - The reactivity of a diruthenium tetrahydride complex towards three selected dihydroboranes was investigated. The use of [DurBH\(_{2}\)] (Dur=2,3,5,6‐Me\(_{4}\)C\(_{6}\)H) and [(Me\(_{3}\)Si)\(_{2}\)NBH\(_{2}\)] led to the formation of bridging borylene complexes of the form [(Cp\(^{*}\)RuH)\(_{2}\)BR] (Cp\(^{*}\)=C\(_{5}\)Me\(_{5}\); 1 a: R=Dur; 1 b: R=N(SiMe\(_{3}\))\(_{2}\)) through oxidative addition of the B−H bonds with concomitant hydrogen liberation. Employing the more electron‐deficient dihydroborane [3,5‐(CF\(_{3}\))\(_{2}\)‐C\(_{6}\)H\(_{3}\)BH\(_{2}\)] led to the formation of an anionic complex bearing a tetraarylated chain of four boron atoms, namely Li(THF)\(_{4}\)[(Cp\(^{*}\)Ru)\(_{2}\)B\(_{4}\)H\(_{5}\)(3,5‐(CF\(_{3}\))\(_{2}\)C\(_{6}\)H\(_{3}\))\(_{4}\)] (4), through an unusual, incomplete threefold dehydrocoupling process. A comparative theoretical investigation of the bonding in a simplified model of 4 and the analogous complex nido‐[1,2(Cp\(^{*}\)Ru)\(_{2}\)(μ‐H)B\(_{4}\)H\(_{9}\)] (I) indicates that there appear to be no classical σ‐bonds between the boron atoms in complex I, whereas in the case of 4 the B\(_{4}\) chain better resembles a network of three B−B σ bonds, the central bond being significantly weaker than the other two.
KW  - transition metal
KW  - B−H activation
KW  - boron
KW  - dehydrocoupling
KW  - ruthenium
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-214324
VL  - 25
IS  - 72
ER  - 
TY  - JOUR
A1  - Huang, Zhenguo
A1  - Wang, Suning
A1  - Dewhurst, Rian D.
A1  - Ignat'ev, Nikolai V.
A1  - Finze, Maik
A1  - Braunschweig, Holger
T1  - Boron: Its Role in Energy‐Related Processes and Applications
JF  - Angewandte Chemie International Edition
N2  - Boron's unique position in the Periodic Table, that is, at the apex of the line separating metals and nonmetals, makes it highly versatile in chemical reactions and applications. Contemporary demand for renewable and clean energy as well as energy‐efficient products has seen boron playing key roles in energy‐related research, such as 1) activating and synthesizing energy‐rich small molecules, 2) storing chemical and electrical energy, and 3) converting electrical energy into light. These applications are fundamentally associated with boron's unique characteristics, such as its electron‐deficiency and the availability of an unoccupied p orbital, which allow the formation of a myriad of compounds with a wide range of chemical and physical properties. For example, boron's ability to achieve a full octet of electrons with four covalent bonds and a negative charge has led to the synthesis of a wide variety of borate anions of high chemical and electrochemical stability—in particular, weakly coordinating anions. This Review summarizes recent advances in the study of boron compounds for energy‐related processes and applications.
KW  - boron
KW  - electrolytes
KW  - hydrogen
KW  - OLEDs
KW  - small-molecule activation
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-218514
VL  - 59
IS  - 23
SP  - 8800
EP  - 8816
ER  - 
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  - Hermann, Alexander
A1  - Fantuzzi, Felipe
A1  - Arrowsmith, Merle
A1  - Zorn, Theresa
A1  - Krummenacher, Ivo
A1  - Ritschel, Benedikt
A1  - Radacki, Krzysztof
A1  - Engels, Bernd
A1  - Braunschweig, Holger
T1  - Oxidation, Coordination, and Nickel-Mediated Deconstruction of a Highly Electron-Rich Diboron Analogue of 1,3,5-Hexatriene
JF  - Angewandte Chemie, International Edition
N2  - The reductive coupling of an N-heterocyclic carbene (NHC) stabilized (dibromo)vinylborane yields a 1,2-divinyl- diborene, which, although isoelectronic to a 1,3,5-triene, displays no extended p conjugation because of twisting of the C\(_2\)B\(_2\)C\(_2\) chain. While this divinyldiborene coordinates to copper(I) and platinum(0) in an η\(^2\)-B\(_2\) and η\(^4\)-C\(_2\)B\(_2\) fashion, respectively, it undergoes a complex rearrangement to an η\(^4\)-1,3-diborete upon complexation with nickel(0).
KW  - boron
KW  - diborenes
KW  - carbenes
KW  - conjugation
KW  - density-functional calculations
KW  - rearrangements
KW  - structure elucidation
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-240652
VL  - 59
IS  - 36
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  - Adducts of the parent boraphosphaketene H\(_2\)BPCO and their decarbonylative insertion chemistry
JF  - Angewandte Chemie International Edition
N2  - The first examples of Lewis base adducts of the parent boraphosphaketene (H\(_2\)B-PCO) and their cyclodimers are prepared. One of these adducts is shown to undergo mild decarbonylation and phosphinidene insertion into a B−C bond of a borole, forming very rare examples of 1,2-phosphaborinines, B/P isosteres of benzene. The strong donor properties of these 1,2-phosphaborinines are confirmed by the synthesis of their π complexes with the Group 6 metals.
KW  - inorganic chemistry
KW  - phosphorus
KW  - boron
KW  - decarbonylation
KW  - heterocycles
KW  - ketenes
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256470
VL  - 60
IS  - 24
ER  - 
TY  - JOUR
A1  - Gärtner, Annalena
A1  - Marek, Matthäus
A1  - Arrowsmith, Merle
A1  - Auerhammer, Dominic
A1  - Radacki, Krzysztof
A1  - Prieschl, Dominic
A1  - Dewhurst, Rian D.
A1  - Braunschweig, Holger
T1  - Boron- versus Nitrogen-Centered Nucleophilic Reactivity of (Cyano)hydroboryl Anions: Synthesis of Cyano(hydro)organoboranes and 2-Aza-1,4-diborabutatrienes
JF  - Chemistry—A European Journal
N2  - Cyclic alkyl(amino)carbene-stabilized (cyano)hydroboryl anions were synthesized by deprotonation of (cyano)dihydroborane precursors. While they display boron-centered nucleophilic reactivity towards organohalides, generating fully unsymmetrically substituted cyano(hydro)organoboranes, they show cyano-nitrogen-centered nucleophilic reactivity towards haloboranes, resulting in the formation of hitherto unknown linear 2-aza-1,4-diborabutatrienes.
KW  - nucleophile
KW  - boron
KW  - boryl anion
KW  - cumulene
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256853
VL  - 27
IS  - 37
ER  - 
TY  - JOUR
A1  - Goettel, James T.
A1  - Gao, Haopeng
A1  - Dotzauer, Simon
A1  - Braunschweig, Holger
T1  - \(^{Me}\)CAAC=N\(^{-}\): A Cyclic (Alkyl)(Amino)Carbene Imino Ligand
JF  - Chemistry – A European Journal
N2  - A cyclic (alkyl)(amino)carbene (CAAC) has been shown to react with a covalent azide similar to the Staudinger reaction. The reaction of \(^{Me}\)CAAC with trimethylsilyl azide afforded the N‐silylated 2‐iminopyrrolidine (\(^{Me}\)CAAC=NSiMe\(_{3}\)), which was fully characterized. This compound undergoes hydrolysis to afford the 2‐iminopyrrolidine and trimethylsiloxane which co‐crystallize as a hydrogen‐bonded adduct. The N‐silylated 2‐iminopyrrolidine was used to transfer the novel pyrrolidine‐2‐iminato ligand onto both main‐group and transition‐metal centers. The reaction of the tetrabromodiborane bis(dimethyl sulfide) adduct with two equivalents of \(^{Me}\)CAAC=NSiMe\(_{3}\) afforded the disubstituted diborane. The reaction of \(^{Me}\)CAAC=NSiMe\(_{3}\) with TiCl\(_{4}\) and CpTiCl\(_{3}\) afforded \(^{Me}\)CAAC=NTiCl\(_{3}\) and \(^{Me}\)CAAC=NTiCl\(_{2}\)Cp, respectively.
KW  - boron
KW  - carbenes
KW  - imide ligands
KW  - nitrogen ligands
KW  - titanium
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-212662
VL  - 26
IS  - 5
ER  - 
TY  - JOUR
A1  - Ewing, William C.
A1  - Dellermann, Theresa
A1  - Angel Wong, Y. T.
A1  - Mattock, James D.
A1  - Vargas, Alfredo
A1  - Bryce, David L.
A1  - Dewhurst, Rian D.
A1  - Braunschweig, Holger
T1  - \(\pi\)‐Complexes of Diborynes with Main Group Atoms
JF  - Chemistry – An Asian Journal
N2  - We present herein an in‐depth study of complexes in which a molecule containing a boron‐boron triple bond is bound to tellurate cations. The analysis allows the description of these salts as true π complexes between the B−B triple bond and the tellurium center. These complexes thus extend the well‐known Dewar‐Chatt‐Duncanson model of bonding to compounds made up solely of p block elements. Structural, spectroscopic and computational evidence is offered to argue that a set of recently reported heterocycles consisting of phenyltellurium cations complexed to diborynes bear all the hallmarks of \(\pi\)‐complexes in the \(\pi\)‐complex/metallacycle continuum envisioned by Joseph Chatt. Described as such, these compounds are unique in representing the extreme of a metal‐free continuum with conventional unsaturated three‐membered rings (cyclopropenes, azirenes, borirenes) occupying the opposite end.
KW  - boron
KW  - main group elements
KW  - solid-state NMR
KW  - \(\pi\) interactions
KW  - multiple bonds
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-214677
VL  - 15
IS  - 10
SP  - 1553
EP  - 1557
ER  - 
TY  - JOUR
A1  - Cui, Jingjing
A1  - Dietz, Maximilian
A1  - Härterich, Marcel
A1  - Fantuzzi, Felipe
A1  - Lu, Wei
A1  - Dewhurst, Rian D.
A1  - Braunschweig, Holger
T1  - Diphosphino-Functionalized 1,8-Naphthyridines: a Multifaceted Ligand Platform for Boranes and Diboranes
JF  - Chemistry—A European Journal
N2  - A 1,8-naphthyridine diphosphine (NDP) reacts with boron-containing Lewis acids to generate complexes featuring a number of different naphthyridine bonding modes. When exposed to diborane B\(_{2}\)Br\(_{4}\), NDP underwent self-deprotonation to afford [NDP-B\(_{2}\)Br\(_{3}\)]Br, an unsymmetrical diborane comprised of four fused rings. The reaction of two equivalents of monoborane BBr\(_{3}\) and NDP in a non-polar solvent provided the simple phosphine-borane adduct [NDP(BBr\(_{3}\))\(_{2}\)], which then underwent intramolecular halide abstraction to furnish the salt [NDP-BBr\(_{2}\)][BBr\(_{4}\)], featuring a different coordination mode from that of [NDP-B\(_{2}\)Br\(_{3}\)]Br. Direct deprotonation of NDP by KHMDS or PhCH2K generates mono- and dipotassium reagents, respectively. The monopotassium reagent reacts with one or half an equivalent of B\(_{2}\)(NMe\(_{2}\))\(_{2}\)Cl\(_{2}\) to afford NDP-based diboranes with three or four amino substituents.
KW  - pincer ligand
KW  - potassium reagent
KW  - diborane
KW  - naphthyridine
KW  - boron
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256994
VL  - 27
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  - 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 diborenes and their 90°-twisted diradical congeners
JF  - 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  - chemical bonding
KW  - diradicals
KW  - organometallic chemistry
KW  - diborenes
KW  - carbenes
KW  - boron
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-160431
VL  - 9
IS  - Article number: 1197
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  - JOUR
A1  - Bélanger‐Chabot, Guillaume
A1  - Braunschweig, Holger
T1  - Hexahalodiborate Dianions: A New Family of Binary Boron Halides
JF  - Angewandte Chemie International Edition
N2  - The electron‐precise binary boron subhalide species [B\(_2\)X\(_6\)]\(^{2−}\) X=F, Br, I) were synthesized and their structures confirmed by X‐ray crystallography. The existence of the previously claimed [B\(_2\)Cl\(_6\)]\(^{2−}\), which had been questioned, was also confirmed by X‐ray crystallography. The dianions are isoelectronic to hexahaloethanes, are subhalide analogues of the well‐known tetrahaloborate anions (BX\(_4\)\(^−\)), and are rare examples of molecular electron‐precise binary boron species beyond B\(_2\)X\(_4\), BX\(_3\), and [BX\(_4\)]\(^−\).
KW  - binary species
KW  - boron
KW  - electron-precise diborates
KW  - halogens
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-219688
VL  - 58
IS  - 40
ER  - 
TY  - JOUR
A1  - Brückner, Tobias
A1  - Heß, Merlin
A1  - Stennett, Tom E.
A1  - Rempel, Anna
A1  - Braunschweig, Holger
T1  - Synthesis of Boron Analogues of Enamines via Hydroamination of a Boron-Boron Triple Bond
BT  - Dedicated to Professor Wolfgang Kaim on the occasion of his 70th birthday
JF  - Angewandte Chemie, International Edition
N2  - An N-heterocyclic-carbene-stabilized diboryne undergoes rapid, high-yielding and catalyst-free hydroamina- tion reactions with primary amines, yielding 1-amino-2-hydro- diborenes, which can be considered boron analogues of enamines. The electronics of the organic substituent at nitrogen influence the structure and further reactivity of the diborene product. With electron-rich anilines, a second hydroamination can occur at the diborene to generate 1,1-diamino-2,2-dihy- drodiboranes. With isopropylamine, the electronic influence of the alkyl substituent upon the diborene leads to an unprece- dented boron-mediated intramolecular N-dearylation reaction of an N-heterocyclic carbene unit.
KW  - boron
KW  - diborynes
KW  - diborenes
KW  - DFT
KW  - enamines
KW  - hydroamination
KW  - multiple bonds
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-240669
VL  - 60
IS  - 2
ER  -