@article{WeiserCuiDewhurstetal.2023,
  author    = {Weiser, Jonas and Cui, Jingjing and Dewhurst, Rian D. and Braunschweig, Holger and Engels, Bernd and Fantuzzi, Felipe},
  title     = {Structure and bonding of proximity-enforced main-group dimers stabilized by a rigid naphthyridine diimine ligand},
  series = {Journal of Computational Chemistry},
  volume    = {44},
  journal   = {Journal of Computational Chemistry},
  number    = {3},
  doi       = {10.1002/jcc.26994},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312586},
  pages     = {456 -- 467},
  year      = {2023},
  abstract  = {The development of ligands capable of effectively stabilizing highly reactive main-group species has led to the experimental realization of a variety of systems with fascinating properties. In this work, we computationally investigate the electronic, structural, energetic, and bonding features of proximity-enforced group 13-15 homodimers stabilized by a rigid expanded pincer ligand based on the 1,8-naphthyridine (napy) core. We show that the redox-active naphthyridine diimine (NDI) ligand enables a wide variety of structural motifs and element-element interaction modes, the latter ranging from isolated, element-centered lone pairs (e.g., E = Si, Ge) to cases where through-space π bonds (E = Pb), element-element multiple bonds (E = P, As) and biradical ground states (E = N) are observed. Our results hint at the feasibility of NDI-E2 species as viable synthetic targets, highlighting the versatility and potential applications of napy-based ligands in main-group chemistry.},
  language  = {en}
}
@article{LindlLamprechtArrowsmithetal.2023,
  author    = {Lindl, Felix and Lamprecht, Anna and Arrowsmith, Merle and Khitro, Eugen and Rempel, Anna and Dietz, Maximilian and Wellnitz, Tim and B{\´e}langer-Chabot, Guillaume and Stoy, Andreas and Paprocki, Valerie and Prieschl, Dominik and Lenczyk, Carsten and Ramler, Jacqueline and Lichtenberg, Crispin and Braunschweig, Holger},
  title     = {Aromatic 1,2-Azaborinin-1-yls as Electron-Withdrawing Anionic Nitrogen Ligands for Main Group Elements},
  series = {Chemistry - A European Journal},
  volume    = {29},
  journal   = {Chemistry - A European Journal},
  number    = {11},
  doi       = {10.1002/chem.202203345},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312222},
  year      = {2023},
  abstract  = {The 2-aryl-3,4,5,6-tetraphenyl-1,2-azaborinines 1-EMe\(_{3}\) and 2-EMe\(_{3}\) (E=Si, Sn; aryl=Ph (1), Mes (=2,4,6-trimethylphenyl, 2)) were synthesized by ring-expansion of borole precursors with N\(_{3}\)EMe\(_{3}\)-derived nitrenes. Desilylative hydrolysis of 1- and 2-SiMe\(_{3}\) yielded the corresponding N-protonated azaborinines, which were deprotonated with nBuLi or MN(SiMe\(_{3}\))\(_{2}\) (M=Na, K) to the corresponding group 1 salts, 1-M and 2-M. While the lithium salts crystallized as monomeric Lewis base adducts, the potassium salts formed coordination polymers or oligomers via intramolecular K⋅⋅⋅aryl π interactions. The reaction of 1-M or 2-M with CO\(_{2}\) yielded N-carboxylate salts, which were derivatized by salt metathesis to methyl and silyl esters. Salt metathesis of 1-M or 2-M with methyl triflate, [Cp*BeCl] (Cp*=C\(_{5}\)Me\(_{5}\)), BBr\(_{2}\)Ar (Ar=Ph, Mes, 2-thienyl), ECl\(_{3}\) (E=B, Al, Ga) and PX\(_{3}\) (X=Cl, Br) afforded the respective group 2, 13 and 15 1,2-azaborinin-2-yl complexes. Salt metathesis of 1-K with BBr\(_{3}\) resulted not only in N-borylation but also Ph-Br exchange between the endocyclic and exocyclic boron atoms. Solution \(^{11}\)B NMR data suggest that the 1,2-azaborinin-2-yl ligand is similarly electron-withdrawing to a bromide. In the solid state the endocyclic bond length alternation and the twisting of the C\(_{4}\)BN ring increase with the sterics of the substituents at the boron and nitrogen atoms, respectively. Regression analyses revealed that the downfield shift of the endocyclic \(^{11}\)B NMR resonances is linearly correlated to both the degree of twisting of the C\(_{4}\)BN ring and the tilt angle of the N-substituent. Calculations indicate that the 1,2-azaborinin-1-yl ligand has no sizeable π-donor ability and that the aromaticity of the ring can be subtly tuned by the electronics of the N-substituent.},
  language  = {en}
}
@article{WitteArrowsmithLamprechtetal.2023,
  author    = {Witte, Robert and Arrowsmith, Merle and Lamprecht, Anna and Schorr, Fabian and Krummenacher, Ivo and Braunschweig, Holger},
  title     = {C-C and C-N Bond Activation, Lewis-Base Coordination and One- and Two-Electron Oxidation at a Linear Aminoborylene},
  series = {Chemistry - A European Journal},
  volume    = {29},
  journal   = {Chemistry - A European Journal},
  number    = {16},
  doi       = {10.1002/chem.202203663},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312491},
  year      = {2023},
  abstract  = {A cyclic alkyl(amino)carbene (CAAC)-stabilized dicoordinate aminoborylene is synthesized by the twofold reduction of a [(CAAC)BCl\(_{2}\)(TMP)] (TMP=2,6-tetramethylpiperidyl) precursor. NMR-spectroscopic, X-ray crystallographic and computational analyses confirm the cumulenic nature of the central C=B=N moiety. Irradiation of [(CAAC)B(TMP)] (2) resulted in an intramolecular C-C bond activation, leading to a doubly-fused C\(_{10}\)BN heterocycle, while the reaction with acetonitrile resulted in an aryl migration from the CAAC to the acetonitrile nitrogen atom, concomitant with tautomerization of the latter to a boron-bound allylamino ligand. One-electron oxidation of 2 with CuX (X=Cl, Br) afforded the corresponding amino(halo)boryl radicals, which were characterized by EPR spectroscopy and DFT calculations. Placing 2 under an atmosphere of CO afforded the tricoordinate (CAAC,CO)-stabilized aminoborylene. Finally, the twofold oxidation of 2 with chalcogens led, in the case of N\(_{2}\)O and sulfur, to the splitting of the B-C\(_{CAAC}\) bond and formation of the 2,4-diamino-1,3,2,4-dichalcogenadiboretanes and CAAC-chalcogen adducts, whereas with selenium a monomeric boraselenone was isolated, which showed some degree of B-Se multiple bonding.},
  language  = {en}
}
@article{BruecknerRitschelJimenez‐Hallaetal.2023,
  author    = {Br{\"u}ckner, Tobias and Ritschel, Benedikt and Jim{\´e}nez-Halla, J. Oscar C. and Fantuzzi, Felipe and Duwe, Dario and Markl, Christian and Dewhurst, Rian D. and Dietz, Maximilian and Braunschweig, Holger},
  title     = {Metal-Free Intermolecular C-H Borylation of N-Heterocycles at B-B Multiple Bonds},
  series = {Angewandte Chemie International Edition},
  volume    = {62},
  journal   = {Angewandte Chemie International Edition},
  number    = {5},
  doi       = {10.1002/anie.202213284},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312385},
  year      = {2023},
  abstract  = {Carbene-stabilized diborynes of the form LBBL (L=N-heterocyclic carbene (NHC) or cyclic alkyl(amino)carbene (CAAC)) induce rapid, high yielding, intermolecular ortho-C-H borylation at N-heterocycles at room temperature. A simple pyridyldiborene is formed when an NHC-stabilized diboryne is combined with pyridine, while a CAAC-stabilized diboryne leads to activation of two pyridine molecules to give a tricyclic alkylideneborane, which can be forced to undergo a further H-shift resulting in a zwitterionic, doubly benzo-fused 1,3,2,5-diazadiborinine by heating. Use of the extended N-heteroaromatic quinoline leads to a borylmethyleneborane under mild conditions via an unprecedented boron-carbon exchange process.},
  language  = {en}
}
@article{HaerterichMatlerDewhurstetal.2023,
  author    = {H{\"a}rterich, Marcel and Matler, Alexander and Dewhurst, Rian D. and Sachs, Andreas and Oppel, Kai and Stoy, Andreas and Braunschweig, Holger},
  title     = {A step-for-step main-group replica of the Fischer carbene synthesis at a borylene carbonyl},
  series = {Nature Communications},
  volume    = {14},
  journal   = {Nature Communications},
  doi       = {10.1038/s41467-023-36251-3},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-357270},
  year      = {2023},
  abstract  = {The Fischer carbene synthesis, involving the conversion of a transition metal (TM)-bound CO ligand to a carbene ligand of the form [=C(OR')R] (R, R' = organyl groups), is one of the seminal reactions in the history of organometallic chemistry. Carbonyl complexes of p-block elements, of the form [E(CO)n] (E = main-group fragment), are much less abundant than their TM cousins; this scarcity and the general instability of low-valent p-block species means that replicating the historical reactions of TM carbonyls is often very difficult. Here we present a step-for-step replica of the Fischer carbene synthesis at a borylene carbonyl involving nucleophilic attack at the carbonyl carbon followed by electrophilic quenching at the resultant acylate oxygen atom. These reactions provide borylene acylates and alkoxy-/silyloxy-substituted alkylideneboranes, main-group analogues of the archetypal transition metal acylate and Fischer carbene families, respectively. When either the incoming electrophile or the boron center has a modest steric profile, the electrophile instead attacks at the boron atom, leading to carbene-stabilized acylboranes - boron analogues of the well-known transition metal acyl complexes. These results constitute faithful main-group replicas of a number of historical organometallic processes and pave the way to further advances in the field of main-group metallomimetics.},
  language  = {en}
}
@article{FullWoelflickRadackietal.2022,
  author    = {Full, Felix and W{\"o}lflick, Quentin and Radacki, Krzysztof and Braunschweig, Holger and Nowak-Kr{\´o}l, Agnieszka},
  title     = {Enhanced Optical Properties of Azaborole Helicenes by Lateral and Helical Extension},
  series = {Chemistry - A European Journal},
  volume    = {28},
  journal   = {Chemistry - A European Journal},
  number    = {62},
  doi       = {10.1002/chem.202202280},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-293671},
  year      = {2022},
  abstract  = {The synthesis and characterization of laterally extended azabora[5]-, -[6]- and -[7]helicenes, assembled from N-heteroaromatic and dibenzo[g,p]chrysene building blocks is described. Formally, the π-conjugated systems of the pristine azaborole helicenes were enlarged with a phenanthrene unit leading to compounds with large Stokes shifts, significantly enhanced luminescence quantum yields (Φ) and dissymmetry factors (g\(_{lum}\)). The beneficial effect on optical properties was also observed for helical elongation. The combined contributions of lateral and helical extensions resulted in a compound showing green emission with Φ of 0.31 and |g\(_{lum}\)| of 2.2×10\(^{-3}\), highest within the series of π-extended azaborahelicenes and superior to emission intensity and chiroptical response of its non-extended congener. This study shows that helical and lateral extensions of π-conjugated systems are viable strategies to improve features of azaborole helicenes. In addition, single crystal X-ray analysis of configurationally stable [6]- and -[7]helicenes was used to provide insight into their packing arrangements.},
  language  = {en}
}
@article{KoleKošćakAmaretal.2022,
  author    = {Kole, Goutam Kumar and Košćak, Marta and Amar, Anissa and Majhen, Dragomira and Božinović, Ksenija and Brkljaca, Zlatko and Ferger, Matthias and Michail, Evripidis and Lorenzen, Sabine and Friedrich, Alexandra and Krummenacher, Ivo and Moos, Michael and Braunschweig, Holger and Boucekkine, Abdou and Lambert, Christoph and Halet, Jean-Fran{\c{c}}ois and Piantanida, Ivo and M{\"u}ller-Buschbaum, Klaus and Marder, Todd B.},
  title     = {Methyl Viologens of Bis-(4'-Pyridylethynyl)Arenes - Structures, Photophysical and Electrochemical Studies, and their Potential Application in Biology},
  series = {Chemistry - A European Journal},
  volume    = {28},
  journal   = {Chemistry - A European Journal},
  number    = {40},
  doi       = {10.1002/chem.202200753},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-287126},
  year      = {2022},
  abstract  = {A series of bis-(4'-pyridylethynyl)arenes (arene=benzene, tetrafluorobenzene, and anthracene) were synthesized and their bis-N-methylpyridinium compounds were investigated as a class of π-extended methyl viologens. Their structures were determined by single crystal X-ray diffraction, and their photophysical and electrochemical properties (cyclic voltammetry), as well as their interactions with DNA/RNA were investigated. The dications showed bathochromic shifts in emission compared to the neutral compounds. The neutral compounds showed very small Stokes shifts, which are a little larger for the dications. All of the compounds showed very short fluorescence lifetimes (<4 ns). The neutral compound with an anthracene core has a quantum yield of almost unity. With stronger acceptors, the analogous bis-N-methylpyridinium compound showed a larger two-photon absorption cross-section than its neutral precursor. All of the dicationic compounds interact with DNA/RNA; while the compounds with benzene and tetrafluorobenzene cores bind in the grooves, the one with an anthracene core intercalates as a consequence of its large, condensed aromatic linker moiety, and it aggregates within the polynucleotide when in excess over DNA/RNA. Moreover, all cationic compounds showed highly specific CD spectra upon binding to ds-DNA/RNA, attributed to the rare case of forcing the planar, achiral molecule into a chiral rotamer, and negligible toxicity toward human cell lines at ≤10 μM concentrations. The anthracene-analogue exhibited intracellular accumulation within lysosomes, preventing its interaction with cellular DNA/RNA. However, cytotoxicity was evident at 1 μM concentration upon exposure to light, due to singlet oxygen generation within cells. These multi-faceted features, in combination with its two-photon absorption properties, suggest it to be a promising lead compound for development of novel light-activated theranostic agents.},
  language  = {en}
}
@article{FergerRogerKoesteretal.2022,
  author    = {Ferger, Matthias and Roger, Chantal and K{\"o}ster, Eva and Rauch, Florian and Lorenzen, Sabine and Krummenacher, Ivo and Friedrich, Alexandra and Košćak, Marta and Nestić, Davor and Braunschweig, Holger and Lambert, Christoph and Piantanida, Ivo and Marder, Todd B.},
  title     = {Electron-Rich EDOT Linkers in Tetracationic bis-Triarylborane Chromophores: Influence on Water Stability, Biomacromolecule Sensing, and Photoinduced Cytotoxicity},
  series = {Chemistry - A European Journal},
  volume    = {28},
  journal   = {Chemistry - A European Journal},
  number    = {48},
  doi       = {10.1002/chem.202201130},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-287241},
  year      = {2022},
  abstract  = {Three novel tetracationic bis-triarylboranes with 3,4-ethylenedioxythiophene (EDOT) linkers, and their neutral precursors, showed significant red-shifted absorption and emission compared to their thiophene-containing analogues, with one of the EDOT-derivatives emitting in the NIR region. Only the EDOT-linked trixylylborane tetracation was stable in aqueous solution, indicating that direct attachment of a thiophene or even 3-methylthiophene to the boron atom is insufficient to provide hydrolytic stability in aqueous solution. Further comparative analysis of the EDOT-linked trixylylborane tetracation and its bis-thiophene analogue revealed efficient photo-induced singlet oxygen production, with the consequent biological implications. Thus, both analogues bind strongly to ds-DNA and BSA, very efficiently enter living human cells, accumulate in several different cytoplasmic organelles with no toxic effect but, under intense visible light irradiation, they exhibit almost instantaneous and very strong cytotoxic effects, presumably attributed to singlet oxygen production. Thus, both compounds are intriguing theranostic agents, whose intracellular and probably intra-tissue location can be monitored by strong fluorescence, allowing switching on of the strong bioactivity by well-focused visible light.},
  language  = {en}
}
@article{BachmannHelbigCrumbachetal.2022,
  author    = {Bachmann, Jonas and Helbig, Andreas and Crumbach, Merian and Krummenacher, Ivo and Braunschweig, Holger and Helten, Holger},
  title     = {Fusion of Aza- and Oxadiborepins with Furans in a Reversible Ring-Opening Process Furnishes Versatile Building Blocks for Extended π-Conjugated Materials},
  series = {Chemistry - A European Journal},
  volume    = {28},
  journal   = {Chemistry - A European Journal},
  number    = {63},
  doi       = {10.1002/chem.202202455},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-293926},
  year      = {2022},
  abstract  = {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.},
  language  = {en}
}
@article{DietzArrowsmithReichletal.2022,
  author    = {Dietz, Maximilian and Arrowsmith, Merle and Reichl, Stephan and Lugo-Fuentes, Leonardo I. and Jim{\´e}nez-Halla, J. Oscar C. and Scheer, Manfred and Braunschweig, Holger},
  title     = {Stable Two-Legged Parent Piano-Stool and Mixed Diborabenzene-E\(_{4}\) (E=P, As) Sandwich Complexes of Group 8},
  series = {Angewandte Chemie International Edition},
  volume    = {61},
  journal   = {Angewandte Chemie International Edition},
  number    = {36},
  doi       = {10.1002/anie.202206840},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-293880},
  year      = {2022},
  abstract  = {A cyclic alkyl(amino)carbene-stabilized 1,4-diborabenzene (DBB) ligand enables the isolation of 18-electron two-legged parent piano-stool Fe\(^{0}\) and Ru\(^{0}\) complexes, [(η\(^{6}\)-DBB)M(CO)\(_{2}\)], the ruthenium complex being the first of its kind to be structurally characterized. [(η\(^{6}\)-DBB)Fe(CO)\(_{2}\)] reacts with E\(_{4}\) (E=P, As) to yield mixed DBB-cyclo-E\(_{4}\) sandwich complexes with planar E\(_{4}\)\(^{2-}\) ligands. Computational analyses confirm the strong electron-donating capacity of the DBB ligand and show that the E\(_{4}\) ligand is bound by four equivalent Fe-P σ bonds.},
  language  = {en}
}
@article{HuangHuKrummenacheretal.2022,
  author    = {Huang, Mingming and Hu, Jiefeng and Krummenacher, Ivo and Friedrich, Alexandra and Braunschweig, Holger and Westcott, Stephen A. and Radius, Udo and Marder, Todd B.},
  title     = {Base-Mediated Radical Borylation of Alkyl Sulfones},
  series = {Chemistry—A European Journal},
  volume    = {28},
  journal   = {Chemistry—A European Journal},
  number    = {3},
  doi       = {10.1002/chem.202103866},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-257281},
  pages     = {e202103866},
  year      = {2022},
  abstract  = {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.},
  language  = {en}
}
@article{LuJayaramanFantuzzietal.2022,
  author    = {Lu, Wei and Jayaraman, Arumugam and Fantuzzi, Felipe and Dewhurst, Rian D. and H{\"a}rterich, Marcel and Dietz, Maximilian and Hagspiel, Stephan and Krummenbacher, Ivo and Hammond, Kai and Cui, Jingjing and Braunschweig, Holger},
  title     = {An unsymmetrical, cyclic diborene based on a chelating CAAC ligand and its small-molecule activation and rearrangement chemistry},
  series = {Angewandte Chemie International Edition},
  volume    = {61},
  journal   = {Angewandte Chemie International Edition},
  number    = {3},
  doi       = {10.1002/anie.202113947},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256576},
  year      = {2022},
  abstract  = {A one-pot synthesis of a CAAC-stabilized, unsymmetrical, cyclic diborene was achieved via consecutive two-electron reduction steps from an adduct of CAAC and B\(_2\)Br\(_4\)(SMe\(_2\))\(_2\). Theoretical studies revealed that this diborene has a considerably smaller HOMO-LUMO gap than those of reported NHC- and phosphine-supported diborenes. Complexation of the diborene with [AuCl(PCy\(_3\))] afforded two diborene-Au\(^I\) π complexes, while reaction with DurBH\(_2\), P\(_4\) and a terminal acetylene led to the cleavage of B-H, P-P, and C-C π bonds, respectively. Thermal rearrangement of the diborene gave an electron-rich cyclic alkylideneborane, which readily coordinated to Ag\(^I\) via its B=C double bond.},
  language  = {en}
}
@article{GerlachMonningerSchleieretal.2021,
  author    = {Gerlach, Marius and Monninger, Sophie and Schleier, Domenik and Hemberger, Patrick and Goettel, James T. and Braunschweig, Holger and Fischer, Ingo},
  title     = {Photoelectron Photoion Coincidence Spectroscopy of NCl\(_{3}\) and NCl\(_{2}\)},
  series = {ChemPhysChem},
  volume    = {22},
  journal   = {ChemPhysChem},
  number    = {21},
  doi       = {10.1002/cphc.202100537},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-257322},
  pages     = {2164-2167},
  year      = {2021},
  abstract  = {We investigate NCl\(_{3}\) and the NCl\(_{2}\) radical by photoelectron-photoion coincidence spectroscopy using synchrotron radiation. The mass selected threshold photoelectron spectrum (ms-TPES) of NCl\(_{3}\) is broad and unstructured due to the large geometry change. An ionization energy of 9.7±0.1 eV is estimated from the spectrum and supported by computations. NCl2 is generated by photolysis at 213 nm from NCl\(_{3}\) and its ms-TPES shows an extended vibrational progression with a 90 meV spacing that is assigned to the symmetric N-Cl stretching mode in the cation. An adiabatic ionization energy of 9.94 ± 0.02 eV is determined.},
  language  = {en}
}
@article{HagspielArrowsmithFantuzzietal.2021,
  author    = {Hagspiel, Stephan and Arrowsmith, Merle and Fantuzzi, Felipe and Vargas, Alfredo and Rempel, Anna and Hermann, Alexander and Br{\"u}ckner, Tobias and Braunschweig, Holger},
  title     = {Highly colored boron-doped thiazolothiazoles from the reductive dimerization of boron isothiocyanates},
  series = {Angewandte Chemie International Edition},
  volume    = {60},
  journal   = {Angewandte Chemie International Edition},
  number    = {12},
  doi       = {10.1002/anie.202015508},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256432},
  pages     = {6446-6450},
  year      = {2021},
  abstract  = {Reduction of (CAAC)BBr\(_2\)(NCS) (CAAC=cyclic alkyl(amino)carbene) in the presence of a Lewis base L yields tricoordinate (CAAC)LB(NCS) borylenes which undergo reversible E/Z-isomerization. The same reduction in the absence of L yields deep blue, bis(CAAC)-stabilized, boron-doped, aromatic thiazolothiazoles resulting from the dimerization of dicoordinate (CAAC)B(NCS) borylene intermediates.},
  language  = {en}
}
@article{RienschSwobodaLiketal.2021,
  author    = {Riensch, Nicolas Alexander and Swoboda, Lukas and Lik, Artur and Krummenacher, Ivo and Braunschweig, Holger and Helten, Holger},
  title     = {Conjugated Bis(triarylboranes) with Disconnected Conjugation},
  series = {Zeitschrift f{\"u}r anorganische und allgemeine Chemie},
  volume    = {647},
  journal   = {Zeitschrift f{\"u}r anorganische und allgemeine Chemie},
  number    = {5},
  doi       = {10.1002/zaac.202000476},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-258020},
  pages     = {421-424},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@article{HeRauchFriedrichetal.2021,
  author    = {He, Jiang and Rauch, Florian and Friedrich, Alexandra and Krebs, Johannes and Krummenacher, Ivo and Bertermann, R{\"u}diger and Nitsch, J{\"o}rn and Braunschweig, Holger and Finze, Maik and Marder, Todd B.},
  title     = {Phenylpyridyl-fused boroles: a unique coordination mode and weak B-N coordination-induced dual fluorescence},
  series = {Angewandte Chemie International Edition},
  volume    = {60},
  journal   = {Angewandte Chemie International Edition},
  number    = {9},
  doi       = {10.1002/anie.202013692},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256423},
  pages     = {4833-4840},
  year      = {2021},
  abstract  = {Phenylpyridyl-fused boroles [TipPBB1]\(_4\) and TipPBB2 were synthesized and their properties investigated. [TipPBB1]\(_4\) forms a tetramer in both the solid state and solution. TipPBB2 contains a 4-coordinate boron atom in the solid state but dissociates to give a 3-coordinate boron species in solution. TipPBB2 shows interesting temperature-dependent dual fluorescence in solution because of the equilibrium between 3- and 4-coordinate boron species due to weak N⋅⋅⋅B intermolecular coordination.},
  language  = {en}
}
@article{KrebsHaehnelKrummenacheretal.2021,
  author    = {Krebs, Johannes and Haehnel, Martin and Krummenacher, Ivo and Friedrich, Alexandra and Braunschweig, Holger and Finze, Maik and Ji, Lei and Marder, Todd B.},
  title     = {Synthesis and Structure of an o-Carboranyl-Substituted Three-Coordinate Borane Radical Anion},
  series = {Chemistry—A European Journal},
  volume    = {27},
  journal   = {Chemistry—A European Journal},
  number    = {31},
  doi       = {10.1002/chem.202100938},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256841},
  pages     = {8159-8167},
  year      = {2021},
  abstract  = {Bis(1-(4-tolyl)-carboran-2-yl)-(4-tolyl)-borane [(1-(4-MeC\(_{6}\)H\(_{4}\))-closo-1,2-C\(_{2}\)B\(_{10}\)H\(_{10}\)-2-)\(_{2}\)(4-MeC\(_{6}\)H\(_{4}\))B] (1), a new bis(o-carboranyl)-(R)-borane was synthesised by lithiation of the o-carboranyl precursor and subsequent salt metathesis reaction with (4-tolyl)BBr\(_{2}\). Cyclic voltammetry experiments on 1 show multiple distinct reduction events with a one-electron first reduction. In a selective reduction experiment the corresponding paramagnetic radical anion 1\(^{.-}\) was isolated and characterized. Single-crystal structure analyses allow an in-depth comparison of 1, 1\(^{.-}\), their calculated geometries, and the S\(_{1}\) excited state of 1. Photophysical studies of 1 show a charge transfer (CT) emission with low quantum yield in solution but a strong increase in the solid state. TD-DFT calculations were used to identify transition-relevant orbitals.},
  language  = {en}
}
@article{ArrowsmithEndresHeinzetal.2021,
  author    = {Arrowsmith, Merle and Endres, Sara and Heinz, Myron and Nestler, Vincent and Holthausen, Max C. and Braunschweig, Holger},
  title     = {Probing the Boundaries between Lewis-Basic and Redox Behavior of a Parent Borylene},
  series = {Chemistry—A European Journal},
  volume    = {27},
  journal   = {Chemistry—A European Journal},
  number    = {70},
  doi       = {10.1002/chem.202103256},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-257154},
  pages     = {17660-17668},
  year      = {2021},
  abstract  = {The parent borylene (CAAC)(Me\(_{3}\)P)BH, 1 (CAAC=cyclic alkyl(amino)carbene), acts both as a Lewis base and one-electron reducing agent towards group 13 trichlorides (ECl\(_{3}\), E=B, Al, Ga, In), yielding the adducts 1-ECl\(_{3}\) and increasing proportions of the radical cation [1]\(^{•+}\) for the heavier group 13 analogues. With boron trihalides (BX\(_{3}\), X=F, Cl, Br, I) 1 undergoes sequential adduct formation and halide abstraction reactions to yield borylboronium cations and shows an increasing tendency towards redox processes for the heavier halides. Calculations confirm that 1 acts as a strong Lewis base towards EX3 and show a marked increase in the B-E bond dissociation energies down both group 13 and the halide group.},
  language  = {en}
}
@article{BruecknerFantuzziStennettetal.2021,
  author    = {Br{\"u}ckner, Tobias and Fantuzzi, Felipe and Stennett, Tom E. and Krummenacher, Ivo and Dewhurst, Rian D. and Engels, Bernd and Braunschweig, Holger},
  title     = {Isolation of neutral, mono-, and dicationic B\(_2\)P\(_2\) rings by diphosphorus addition to a boron-boron triple bond},
  series = {Angewandte Chemie International Edition},
  volume    = {60},
  journal   = {Angewandte Chemie International Edition},
  number    = {24},
  doi       = {10.1002/anie.202102218},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256451},
  pages     = {13661-13665},
  year      = {2021},
  abstract  = {The NHC-stabilised diboryne (B\(_2\)(SIDep)\(_2\); SIDep=1,3-bis(2,6-diethylphenyl)imidazolin-2-ylidene) undergoes a high-yielding P-P bond activation with tetraethyldiphosphine at room temperature to form a B\(_2\)P\(_2\) heterocycle via a diphosphoryldiborene by 1,2-diphosphination. The heterocycle can be oxidised to a radical cation and a dication, respectively, depending on the oxidant used and its counterion. Starting from the planar, neutral 1,3-bis(alkylidene)-1,3-diborata-2,4-diphosphoniocyclobutane, each oxidation step leads to decreased B-B distances and loss of planarity by cationisation. X-ray analyses in conjunction with DFT and CASSCF/NEVPT2 calculations reveal closed-shell singlet, butterfly-shaped structures for the NHC-stabilised dicationic B\(_2\)P\(_2\) rings, with their diradicaloid, planar-ring isomers lying close in energy.},
  language  = {en}
}
@article{CzernetzkiArrowsmithFantuzzietal.2021,
  author    = {Czernetzki, Corinna and Arrowsmith, Merle and Fantuzzi, Felipe and G{\"a}rtner, Annalena and Tr{\"o}ster, Tobias and Krummenacher, Ivo and Schorr, Fabian and Braunschweig, Holger},
  title     = {A neutral beryllium(I) radical},
  series = {Angewandte Chemie International Edition},
  volume    = {60},
  journal   = {Angewandte Chemie International Edition},
  number    = {38},
  doi       = {10.1002/anie.202108405},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256529},
  pages     = {20776-20780},
  year      = {2021},
  abstract  = {The reduction of a cyclic alkyl(amino)carbene (CAAC)-stabilized organoberyllium chloride yields the first neutral beryllium radical, which was characterized by EPR, IR, UV/Vis spectroscopy and X-ray crystallography. DFT calculations show significant spin density at beryllium and confirm donor-acceptor bonding between an alkylberyllium radical fragment and a neutral CAAC ligand.},
  language  = {en}
}
@article{CuiDietzHaerterichetal.2021,
  author    = {Cui, Jingjing and Dietz, Maximilian and H{\"a}rterich, Marcel and Fantuzzi, Felipe and Lu, Wei and Dewhurst, Rian D. and Braunschweig, Holger},
  title     = {Diphosphino-Functionalized 1,8-Naphthyridines: a Multifaceted Ligand Platform for Boranes and Diboranes},
  series = {Chemistry—A European Journal},
  volume    = {27},
  journal   = {Chemistry—A European Journal},
  number    = {63},
  doi       = {10.1002/chem.202102721},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256994},
  pages     = {15751-15756},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@article{HagspielFantuzziDewhurstetal.2021,
  author    = {Hagspiel, Stephan and Fantuzzi, Felipe and Dewhurst, Rian D. and G{\"a}rtner, Annalena and Lindl, Felix and Lamprecht, Anna and Braunschweig, Holger},
  title     = {Adducts of the parent boraphosphaketene H\(_2\)BPCO and their decarbonylative insertion chemistry},
  series = {Angewandte Chemie International Edition},
  volume    = {60},
  journal   = {Angewandte Chemie International Edition},
  number    = {24},
  doi       = {10.1002/anie.202103521},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256470},
  pages     = {13666-13670},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@article{SchmidtFantuzziKlopfetal.2021,
  author    = {Schmidt, Paul and Fantuzzi, Felipe and Klopf, Jonas and Schr{\"o}der, Niklas B. and Dewhurst, Rian D. and Braunschweig, Holger and Engel, Volker and Engels, Bernd},
  title     = {Twisting versus delocalization in CAAC- and NHC-stabilized boron-based biradicals: the roles of sterics and electronics},
  series = {Chemistry - A European Journal},
  volume    = {27},
  journal   = {Chemistry - A European Journal},
  number    = {16},
  doi       = {10.1002/chem.202004619},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256636},
  pages     = {5160-5170},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@article{MatlerArrowsmithSchorretal.2021,
  author    = {Matler, Alexander and Arrowsmith, Merle and Schorr, Fabian and Hermann, Alexander and Hofmann, Alexander and Lenczyk, Carsten and Braunschweig, Holger},
  title     = {Reactivity of Terminal Iron Borylenes and Bis(borylenes) with Carbodiimides: Cycloaddition, Metathesis, Insertion and C-H Activation Pathways},
  series = {European Journal of Inorganic Chemistry},
  volume    = {2021},
  journal   = {European Journal of Inorganic Chemistry},
  number    = {45},
  doi       = {10.1002/ejic.202100629},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-257397},
  pages     = {4619-4631},
  year      = {2021},
  abstract  = {The reactions of carbodiimides with the iron arylborylene complex [Fe=BDur(CO)\(_{3}\)(PMe\(_{3}\))] (Dur=2,3,5,6-Me\(_{4}\)C\(_{6}\)H) and the iron bis(borylene) complex [Fe{=BDur}{=BN(SiMe\(_{3}\))\(_{2}\)}(CO)\(_{3}\)] yield a wide variety of temperature-dependent products, including known FeBNC and novel FeBNB metallacycles, complexes of N-heterocyclic boracarbene and spiro-boracarbene ligands and a unique 1,3,2,4-diazadiborolyl pianostool complex, characterized by NMR spectroscopy and X-ray crystallography. The product distributions can be rationalized by considering sequences of cycloaddition, metathesis, insertion, and C-H activation pathways mainly governed by sterics.},
  language  = {en}
}
@article{RoyTroesterFantuzzietal.2021,
  author    = {Roy, Dipak Kumar and Tr{\"o}ster, Tobias and Fantuzzi, Felipe and Dewhurst, Rian D. and Lenczyk, Carsten and Radacki, Krzysztof and Pranckevicius, Conor and Engels, Bernd and Braunschweig, Holger},
  title     = {Isolation and Reactivity of an Antiaromatic s-Block Metal Compound},
  series = {Angewandte Chemie International Edition},
  volume    = {60},
  journal   = {Angewandte Chemie International Edition},
  number    = {7},
  doi       = {10.1002/anie.202014557},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-224447},
  pages     = {3812 -- 3819},
  year      = {2021},
  abstract  = {The concepts of aromaticity and antiaromaticity have a long history, and countless demonstrations of these phenomena have been made with molecules based on elements from the p, d, and f blocks of the periodic table. In contrast, the limited oxidation-state flexibility of the s-block metals has long stood in the way of their participation in sophisticated π-bonding arrangements, and truly antiaromatic systems containing s-block metals are altogether absent or remain poorly defined. Using spectroscopic, structural, and computational techniques, we present herein the synthesis and authentication of a heterocyclic compound containing the alkaline earth metal beryllium that exhibits significant antiaromaticity, and detail its chemical reduction and Lewis-base-coordination chemistry.},
  language  = {en}
}
@article{KoleMerzAmaretal.2021,
  author    = {Kole, Goutam Kumar and Merz, Julia and Amar, Anissa and Fontaine, Bruno and Boucekkine, Abdou and Nitsch, J{\"o}rn and Lorenzen, Sabine and Friedrich, Alexandra and Krummenacher, Ivo and Košćak, Marta and Braunschweig, Holger and Piantanida, Ivo and Halet, Jean-Fran{\c{c}}ois and M{\"u}ller-Buschbaum, Klaus and Marder, Todd B.},
  title     = {2- and 2,7-substituted para-N-methylpyridinium pyrenes: syntheses, molecular and electronic structures, photophysical, electrochemical, and spectroelectrochemical properties and binding to double-stranded (ds) DNA},
  series = {Chemistry - A European Journal},
  volume    = {27},
  journal   = {Chemistry - A European Journal},
  number    = {8},
  doi       = {10.1002/chem.202004748},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256642},
  pages     = {2837-2853},
  year      = {2021},
  abstract  = {Two N-methylpyridinium compounds and analogous N-protonated salts of 2- and 2,7-substituted 4-pyridyl-pyrene compounds were synthesised and their crystal structures, photophysical properties both in solution and in the solid state, electrochemical and spectroelectrochemical properties were studied. Upon methylation or protonation, the emission maxima are significantly bathochromically shifted compared to the neutral compounds, although the absorption maxima remain almost unchanged. As a result, the cationic compounds show very large apparent Stokes shifts of up to 7200 cm\(^{-1}\). The N-methylpyridinium compounds have a single reduction at ca. -1.5 V vs. Fc/Fc\(^+\) in MeCN. While the reduction process was reversible for the 2,7-disubstituted compound, it was irreversible for the mono-substituted one. Experimental findings are complemented by DFT and TD-DFT calculations. Furthermore, the N-methylpyridinium compounds show strong interactions with calf thymus (ct)-DNA, presumably by intercalation, which paves the way for further applications of these multi-functional compounds as potential DNA-bioactive agents.},
  language  = {en}
}
@article{BruecknerHessStennettetal.2021,
  author    = {Br{\"u}ckner, Tobias and Heß, Merlin and Stennett, Tom E. and Rempel, Anna and Braunschweig, Holger},
  title     = {Synthesis of Boron Analogues of Enamines via Hydroamination of a Boron-Boron Triple Bond},
  series = {Angewandte Chemie, International Edition},
  volume    = {60},
  journal   = {Angewandte Chemie, International Edition},
  number    = {2},
  doi       = {10.1002/anie.202012101},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-240669},
  pages     = {736-741},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@article{ZhangRadackiBraunschweigetal.2021,
  author    = {Zhang, Fangyuan and Radacki, Krzysztof and Braunschweig, Holger and Lambert, Christoph and Ravat, Prince},
  title     = {Zinc-[7]helicenocyanine and its discrete π-stacked homochiral Dimer},
  series = {Angewandte Chemie International Edition},
  volume    = {60},
  journal   = {Angewandte Chemie International Edition},
  doi       = {10.1002/anie.202109380},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256534},
  pages     = {23656-23660},
  year      = {2021},
  abstract  = {In this communication, we demonstrate a novel approach to prepare a discrete dimer of chiral phthalocyanine (Pc) by exploiting the flexible molecular geometry of helicenes, which enables structural interlocking and strong aggregation tendency of Pcs. Synthesized [7]helicene-Pc hybrid molecular structure, zinc-[7]helicenocyanine (Zn-7HPc), exclusively forms a stable dimeric pair consisting of two homochiral molecules. The dimerization constants were estimated to be as high as 8.96×10\(^6\) M\(^{-1}\) and 3.42×107 M\(^{-1}\) in THF and DMSO, respectively, indicating remarkable stability of dimer. In addition, Zn\(^{-7}\)HPc exhibited chiral self-sorting behavior, which resulted in preferential formation of a homochiral dimer also in the racemic sample. Two phthalocyanine subunits in the dimeric form strongly communicate with each other as revealed by a large comproportionation constant and observation of an IV-CT band for the thermodynamically stable mixed-valence state.},
  language  = {en}
}
@article{CrumbachBachmannFritzeetal.2021,
  author    = {Crumbach, Merian and Bachmann, Jonas and Fritze, Lars and Helbig, Andreas and Krummenacher, Ivo and Braunschweig, Holger and Helten, Holger},
  title     = {Dithiophene-Fused Oxadiborepins and Azadiborepins: A New Class of Highly Fluorescent Heteroaromatics},
  series = {Angewandte Chemie International Edition},
  volume    = {60},
  journal   = {Angewandte Chemie International Edition},
  number    = {17},
  doi       = {10.1002/anie.202100295},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-238996},
  pages     = {9290 -- 9295},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@article{RamlerFantuzziGeistetal.2021,
  author    = {Ramler, Jaqueline and Fantuzzi, Felipe and Geist, Felix and Hanft, Anna and Braunschweig, Holger and Engels, Bernd and Lichtenberg, Crispin},
  title     = {The dimethylbismuth cation: entry into dative Bi-Bi bonding and unconventional methyl exchange},
  series = {Angewandte Chemie International Edition},
  volume    = {60},
  journal   = {Angewandte Chemie International Edition},
  doi       = {10.1002/anie.202109545},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256543},
  pages     = {24388-24394},
  year      = {2021},
  abstract  = {The dimethyl bismuth cation, [BiMe\(_2\)(SbF\(_6\))], has been isolated and characterized. Reaction with BiMe\(_3\) allows access to the first compound featuring Bi→Bi donor-acceptor bonding. In solution, dynamic behavior with methyl exchange via an unusual S\(_E\)2 mechanism is observed, underlining the unique properties of bismuth species as soft Lewis acids with the ability to undergo reversible Bi-C bond cleavage.},
  language  = {en}
}
@article{SchorrSchopperRienschetal.2021,
  author    = {Schorr, Fabian and Schopper, Nils and Riensch, Nicolas and Fantuzzi, Felipe and Neder, Marco and Dewhurst, Rian D. and Thiess, Thorsten and Br{\"u}ckner, Tobias and Hammond, Kai and Helten, Holger and Finze, Maik and Braunschweig, Holger},
  title     = {Controlled Synthesis of Oligomers Containing Main-Chain B(sp\(^{2}\))-B(sp\(^{2}\)) Bonds},
  series = {Chemistry—A European Journal},
  volume    = {27},
  journal   = {Chemistry—A European Journal},
  number    = {64},
  doi       = {10.1002/chem.202103366},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-257274},
  pages     = {16043-16048},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@article{BergerRueheSchwarzmannetal.2021,
  author    = {Berger, Sarina M. and R{\"u}he, Jessica and Schwarzmann, Johannes and Phillipps, Alexandra and Richard, Ann-Katrin and Ferger, Matthias and Krummenacher, Ivo and Tumir, Lidija-Marija and Ban, Željka and Crnolatac, Ivo and Majhen, Dragomira and Barišić, Ivan and Piantanida, Ivo and Schleier, Domenik and Griesbeck, Stefanie and Friedrich, Alexandra and Braunschweig, Holger and Marder, Todd B.},
  title     = {Bithiophene-Cored, mono-, bis-, and tris-(Trimethylammonium)-Substituted, bis-Triarylborane Chromophores: Effect of the Number and Position of Charges on Cell Imaging and DNA/RNA Sensing},
  series = {Chemistry—A European Journal},
  volume    = {27},
  journal   = {Chemistry—A European Journal},
  number    = {56},
  doi       = {10.1002/chem.202102308},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256963},
  pages     = {14057-14072},
  year      = {2021},
  abstract  = {The synthesis, photophysical, and electrochemical properties of selectively mono-, bis- and tris-dimethylamino- and trimethylammonium-substituted bis-triarylborane bithiophene chromophores are presented along with the water solubility and singlet oxygen sensitizing efficiency of the cationic compounds Cat\(^{1+}\), Cat\(^{2+}\), Cat(i)\(^{2+}\), and Cat\(^{3+}\). Comparison with the mono-triarylboranes reveals the large influence of the bridging unit on the properties of the bis-triarylboranes, especially those of the cationic compounds. Based on these preliminary investigations, the interactions of Cat\(^{1+}\), Cat\(^{2+}\), Cat(i)\(^{2+}\), and Cat\(^{3+}\) with DNA, RNA, and DNApore were investigated in buffered solutions. The same compounds were investigated for their ability to enter and localize within organelles of human lung carcinoma (A549) and normal lung (WI38) cells showing that not only the number of charges but also their distribution over the chromophore influences interactions and staining properties.},
  language  = {en}
}
@article{LindlGuoKrummenacheretal.2021,
  author    = {Lindl, Felix and Guo, Xueying and Krummenacher, Ivo and Rauch, Florian and Rempel, Anna and Paprocki, Valerie and Dellermann, Theresa and Stennett, Tom E. and Lamprecht, Anna and Br{\"u}ckner, Tobias and Radacki, Krzysztof and B{\´e}langer-Chabot, Guillaume and Marder, Todd B. and Lin, Zhenyang and Braunschweig, Holger},
  title     = {Rethinking Borole Cycloaddition Reactivity},
  series = {Chemistry—A European Journal},
  volume    = {27},
  journal   = {Chemistry—A European Journal},
  number    = {43},
  doi       = {10.1002/chem.202101290},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256888},
  pages     = {11226-11233},
  year      = {2021},
  abstract  = {Boroles are attracting broad interest for their myriad and diverse applications, including in synthesis, small molecule activation and functional materials. Their properties and reactivity are closely linked to the cyclic conjugated diene system, which has been shown to participate in cycloaddition reactions, such as the Diels-Alder reaction with alkynes. The reaction steps leading to boranorbornadienes, borepins and tricyclic boracyclohexenes from the thermal reaction of boroles with alkynes are seemingly well understood as judged from the literature. Herein, we question the long-established mechanistic picture of pericyclic rearrangements by demonstrating that seven-membered borepins (i. e., heptaphenylborepin and two derivatives substituted with a thienyl and chloride substituent on boron) exist in a dynamic equilibrium with the corresponding bicyclic boranorbornadienes, the direct Diels-Alder products, but are not isolable products from the reactions. Heating gradually converts the isomeric mixtures into fluorescent tricyclic boracyclohexenes, the most stable isomers in the series. Results from mechanistic DFT calculations reveal that the tricyclic compounds derive from the boranorbornadienes and not the borepins, which were previously believed to be intermediates in purely pericyclic processes.},
  language  = {en}
}
@article{HessKrummenacherDellermannetal.2021,
  author    = {Heß, Merlin and Krummenacher, Ivo and Dellermann, Theresa and Braunschweig, Holger},
  title     = {Rhodium-Mediated Stoichiometric Synthesis of Mono-, Bi-, and Bis-1,2-Azaborinines: 1-Rhoda-3,2-azaboroles as Reactive Precursors},
  series = {Chemistry—A European Journal},
  volume    = {27},
  journal   = {Chemistry—A European Journal},
  number    = {37},
  doi       = {10.1002/chem.202100795},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256830},
  pages     = {9503-9507},
  year      = {2021},
  abstract  = {A series of highly substituted 1,2-azaborinines, including a phenylene-bridged bis-1,2-azaborinine, was synthesized from the reaction of 1,2-azaborete rhodium complexes with variously substituted alkynes. 1-Rhoda-3,2-azaborole complexes, which are accessible by phosphine addition to the corresponding 1,2-azaborete complexes, were also found to be suitable precursors for the synthesis of 1,2-azaborinines and readily reacted with alkynyl-substituted 1,2-azaborinines to generate new regioisomers of bi-1,2-azaborinines, which feature directly connected aromatic rings. Their molecular structures, which can be viewed as boron-nitrogen isosteres of biphenyls, show nearly perpendicular 1,2-azaborinine rings. The new method using rhodacycles instead of 1,2-azaborete complexes as precursors is shown to be more effective, allowing the synthesis of a wider range of 1,2-azaborinines.},
  language  = {en}
}
@article{GaertnerMarekArrowsmithetal.2021,
  author    = {G{\"a}rtner, Annalena and Marek, Matth{\"a}us and Arrowsmith, Merle and Auerhammer, Dominic and Radacki, Krzysztof and Prieschl, Dominic and Dewhurst, Rian D. and Braunschweig, Holger},
  title     = {Boron- versus Nitrogen-Centered Nucleophilic Reactivity of (Cyano)hydroboryl Anions: Synthesis of Cyano(hydro)organoboranes and 2-Aza-1,4-diborabutatrienes},
  series = {Chemistry—A European Journal},
  volume    = {27},
  journal   = {Chemistry—A European Journal},
  number    = {37},
  doi       = {10.1002/chem.202101025},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256853},
  pages     = {9694-9699},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@unpublished{HermannArrowsmithTrujilloGonzalezetal.2020,
  author    = {Hermann, Alexander and Arrowsmith, Merle and Trujillo-Gonzalez, Daniel and Jim{\´e}nez-Halla, J. Oscar C. and Vargas, Alfredo and Braunschweig, Holger},
  title     = {Trapping of a Borirane Intermediate in the Reductive Coupling of an Arylborane to a Diborene},
  series = {Journal of the American Chemical Society},
  journal   = {Journal of the American Chemical Society},
  doi       = {10.1021/jacs.0c02306},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-203140},
  year      = {2020},
  abstract  = {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.},
  language  = {en}
}
@article{StennettJayaramanBrueckneretal.2020,
  author    = {Stennett, Tom E. and Jayaraman, Arumugam and Br{\"u}ckner, Tobias and Schneider, Lea and Braunschweig, Holger},
  title     = {Hydrophosphination of boron-boron multiple bonds},
  series = {Chemical Science},
  volume    = {11},
  journal   = {Chemical Science},
  doi       = {10.1039/c9sc05908c},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-240681},
  pages     = {1335-1341},
  year      = {2020},
  abstract  = {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.},
  language  = {en}
}
@unpublished{SchmidtFantuzziArrowsmithetal.2020,
  author    = {Schmidt, Uwe and Fantuzzi, Felipe and Arrowsmith, Merle and Hermann, Alexander and Prieschl, Dominic and Rempel, Anna and Engels, Bernd and Braunschweig, Holger},
  title     = {Tuneable reduction of cymantrenylboranes to diborenes or borylene-derived boratafulvenes},
  series = {Chemical Communications},
  journal   = {Chemical Communications},
  doi       = {10.1039/D0CC06398C},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-222149},
  year      = {2020},
  abstract  = {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.},
  language  = {en}
}
@article{LiuLegareSeufertetal.2020,
  author    = {Liu, Siyuan and L{\´e}gar{\´e}, Marc-Andr{\´e} and Seufert, Jens and Prieschl, Dominic and Rempel, Anna and Englert, Lukas and Dellermann, Theresa and Paprocki, Valerie and Stoy, Andreas and Braunschweig, Holger},
  title     = {2,2′-Bipyridyl as a Redox-Active Borylene Abstraction Agent},
  series = {Inorganic Chemistry},
  volume    = {59},
  journal   = {Inorganic Chemistry},
  number    = {15},
  doi       = {10.1021/acs.inorgchem.0c01383},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-215595},
  pages     = {10866-10873},
  year      = {2020},
  abstract  = {2,2′-Bipyridyl is shown to spontaneously abstract a borylene fragment (R-B:) from various hypovalent boron compounds. This process is a redox reaction in which the bipyridine is reduced and becomes a dianionic substituent bound to boron through its two nitrogen atoms. Various transition metal-borylene complexes and diboranes, as a well as a diborene, take part in this reaction. In the latter case, our results show an intriguing example of the homolytic cleavage of a B═B double bond.},
  language  = {en}
}
@article{EwingDellermannAngelWongetal.2020,
  author    = {Ewing, William C. and Dellermann, Theresa and Angel Wong, Y. T. and Mattock, James D. and Vargas, Alfredo and Bryce, David L. and Dewhurst, Rian D. and Braunschweig, Holger},
  title     = {\(\pi\)-Complexes of Diborynes with Main Group Atoms},
  series = {Chemistry - An Asian Journal},
  volume    = {15},
  journal   = {Chemistry - An Asian Journal},
  number    = {10},
  doi       = {10.1002/asia.202000185},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-214677},
  pages     = {1553 -- 1557},
  year      = {2020},
  abstract  = {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.},
  language  = {en}
}
@article{ThiessErnstKupferetal.2020,
  author    = {Thiess, Torsten and Ernst, Moritz and Kupfer, Thomas and Braunschweig, Holger},
  title     = {Facile Access to Substituted 1,4-Diaza-2,3-Diborinines},
  series = {Chemistry - A European Journal},
  volume    = {26},
  journal   = {Chemistry - A European Journal},
  number    = {13},
  doi       = {10.1002/chem.201905356},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-214650},
  pages     = {2967 -- 2972},
  year      = {2020},
  abstract  = {Several bis(dimethylamino)-substituted 1,4-diaza-2,3-diborinines (DADBs) were synthesized with variable substituents at the backbone nitrogen atoms. By reaction with HCl or BX\(_{3}\) (X=Br, I), these species were successfully converted into their synthetically more useful halide congeners. The high versatility of the generated B-X bonds in further functionalization reactions at the boron centers was demonstrated by means of salt elimination (MeLi) and commutation (NMe\(_{2}\) DADBs) reactions, thus making the DADB system a general structural motif in diborane(4) chemistry. A total of 18 DADB derivatives were characterized in the solid state by X-ray diffraction, revealing a strong dependence of the heterocyclic bonding parameters from the exocyclic substitution pattern at boron. According to our experiments towards the realization of a Dipp-substituted, sterically encumbered DADB, the mechanism of DADB formation proceeds via a transient four-membered azadiboretidine intermediate that subsequently undergoes ring expansion to afford the six-membered DADB heterocycle.},
  language  = {en}
}
@article{SaalfrankFantuzziKupferetal.2020,
  author    = {Saalfrank, Christian and Fantuzzi, Felipe and Kupfer, Thomas and Ritschel, Benedikt and Hammond, Kai and Krummenacher, Ivo and Bertermann, R{\"u}diger and Wirthensohn, Raphael and Finze, Maik and Schmid, Paul and Engel, Volker and Engels, Bernd and Braunschweig, Holger},
  title     = {cAAC-Stabilized 9,10-diboraanthracenes—Acenes with Open-Shell Singlet Biradical Ground States},
  series = {Angewandte Chemie International Edition},
  volume    = {59},
  journal   = {Angewandte Chemie International Edition},
  number    = {43},
  doi       = {10.1002/anie.202008206},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-217795},
  pages     = {19338 -- 19343},
  year      = {2020},
  abstract  = {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.},
  language  = {en}
}
@article{MerzDietzVonhausenetal.2020,
  author    = {Merz, Julia and Dietz, Maximilian and Vonhausen, Yvonne and W{\"o}ber, Frederik and Friedrich, Alexandra and Sieh, Daniel and Krummenacher, Ivo and Braunschweig, Holger and Moos, Michael and Holzapfel, Marco and Lambert, Christoph and Marder, Todd B.},
  title     = {Synthesis, Photophysical and Electronic Properties of New Red-to-NIR Emitting Donor-Acceptor Pyrene Derivatives},
  series = {Chemistry - A European Journal},
  volume    = {26},
  journal   = {Chemistry - A European Journal},
  number    = {2},
  doi       = {10.1002/chem.201904219},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-207486},
  pages     = {438-453},
  year      = {2020},
  abstract  = {We synthesized new pyrene derivatives with strong bis(para -methoxyphenyl)amine donors at the 2,7-positions and n -azaacene acceptors at the K-region of pyrene. The compounds possess a strong intramolecular charge transfer, leading to unusual properties such as emission in the red to NIR region (700 nm), which has not been reported before for monomeric pyrenes. Detailed photophysical studies reveal very long intrinsic lifetimes of >100 ns for the new compounds, which is typical for 2,7-substituted pyrenes but not for K-region substituted pyrenes. The incorporation of strong donors and acceptors leads to very low reduction and oxidation potentials, and spectroelectrochemical studies show that the compounds are on the borderline between localized Robin-Day class-II and delocalized Robin-Day class-III species.},
  language  = {en}
}
@article{HorrerKrahfussLubitzetal.2020,
  author    = {Horrer, G{\"u}nther and Krahfuß, Mirjam J. and Lubitz, Katharina and Krummenacher, Ivo and Braunschweig, Holger and Radius, Udo},
  title     = {N-Heterocyclic Carbene and Cyclic (Alkyl)(amino)carbene Complexes of Titanium(IV) and Titanium(III)},
  series = {European Journal of Inorganic Chemistry},
  volume    = {2020},
  journal   = {European Journal of Inorganic Chemistry},
  number    = {3},
  doi       = {10.1002/ejic.201901207},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-208725},
  pages     = {281-291},
  year      = {2020},
  abstract  = {The reaction of one and two equivalents of the N -heterocyclic carbene IMes [IMes = 1,3-bis(2,4,6-trimethyl-phenyl)imidazolin-2-ylidene] or the cyclic (alkyl)(amino)carbene cAAC\(^{Me}\) [cAAC\(^{Me}\) = 1-(2,6-diisopropyl-phenyl)-3,3,5,5-tetra-methylpyrrolidin-2-ylidene] with [TiCl\(_{4}\)] in n -hexane results in the formation of mono- and bis-carbene complexes [TiCl\(_{4}\)(IMes)] 1 , [TiCl\(_{4}\)(IMes)2] 2 , [TiCl\(_{4}\)(cAAC\(^{Me}\))] 3 , and [TiCl\(_{4}\)(cAAC\(^{Me}\))\(_{2}\)] 4 , respectively. For comparison, the titanium(IV) NHC complex [TiCl\(_{4}\)(Ii Pr\(^{Me}\))] 5 (Ii Pr\(^{Me}\) = 1,3-diisopropyl-4,5-dimethyl-imidazolin-2-ylidene) has been synthesized and structurally characterized. The reaction of [TiCl\(_{4}\)(IMes)] 1 with PMe\(_{3}\) affords the mixed substituted complex [TiCl\(_{4}\)(IMes)(PMe\(_{3}\))] 6 . The reactions of [TiCl\(_{3}\)(THF)\(_{3}\)] with two equivalents of the carbenes IMes and cAAC\(^{Me}\) in n -hexane lead to the clean formation of the titanium(III) complexes [TiCl\(_{3}\)(IMes)\(_{2}\)] 7 and [TiCl\(_{3}\)(cAAC\(^{Me}\))\(_{2}\)] 8 . Compounds 1 -8 have been completely characterized by elemental analysis, IR and multinuclear NMR spectroscopy and for 2 -5 , 7 and 8 by X-ray diffraction. Magnetometry in solution, EPR and UV/Vis spectroscopy and DFT calculations performed on 7 and 8 are indicative of a predominantly metal-centered d\(^{1}\)-radical in both cases.},
  language  = {en}
}
@article{MerzDietrichNitschetal.2020,
  author    = {Merz, Julia and Dietrich, Lena and Nitsch, J{\"o}rn and Krummenacher, Ivo and Braunschweig, Holger and Moos, Michael and Mims, David and Lambert, Christoph and Marder, Todd B.},
  title     = {Synthesis, Photophysical and Electronic Properties of Mono-, Di-, and Tri-Amino-Substituted Ortho-Perylenes, and Comparison to the Tetra-Substituted Derivative},
  series = {Chemistry - A European Journal},
  volume    = {26},
  journal   = {Chemistry - A European Journal},
  number    = {52},
  doi       = {10.1002/chem.202001475},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-217835},
  pages     = {12050 -- 12059},
  year      = {2020},
  abstract  = {We synthesized a series of new mono-, di-, tri- and tetra-substituted perylene derivatives with strong bis(para-methoxyphenyl)amine (DPA) donors at the uncommon 2,5,8,11-positions. The properties of our new donor-substituted perylenes were studied in detail to establish a structure-property relationship. Interesting trends and unusual properties are observed for this series of new perylene derivatives, such as a decreasing charge transfer (CT) character with increasing number of DPA moieties and individual reversible oxidations for each DPA moiety. Thus, (DPA)-Per possesses one reversible oxidation while (DPA)\(_{4}\)-Per has four. The mono- and di-substituted derivatives display unusually large Stokes shifts not previously reported for perylenes. Furthermore, transient absorption measurements of the new derivatives reveal an excited state with lifetimes of several hundred microseconds, which sensitizes singlet oxygen with quantum yields of up to 0.83.},
  language  = {en}
}
@article{BruneckerMuessigArrowsmithetal.2020,
  author    = {Brunecker, Carina and M{\"u}ssig, Jonas H. and Arrowsmith, Merle and Fantuzzi, Felipe and Stoy, Andreas and B{\"o}hnke, Julian and Hofmann, Alexander and Bertermann, R{\"u}diger and Engels, Bernd and Braunschweig, Holger},
  title     = {Boranediyl- and Diborane(4)-1,2-diyl-Bridged Platinum A-Frame Complexes},
  series = {Chemistry - A European Journal},
  volume    = {26},
  journal   = {Chemistry - A European Journal},
  number    = {39},
  doi       = {10.1002/chem.202001168},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-214707},
  pages     = {8518 -- 8523},
  year      = {2020},
  abstract  = {Diplatinum A-frame complexes with a bridging (di)boron unit in the apex position were synthesized in a single step by the double oxidative addition of dihalo(di)borane precursors at a bis(diphosphine)-bridged Pt\(^{0}\)\(_{2}\) complex. While structurally analogous to well-known μ-borylene complexes, in which delocalized dative three-center-two-electron M-B-M bonding prevails, theoretical investigations into the nature of Pt-B bonding in these A-frame complexes show them to be rare dimetalla(di)boranes displaying two electron-sharing Pt-B σ-bonds. This is experimentally reflected in the low kinetic stability of these compounds, which are prone to loss of the (di)boron bridgehead unit.},
  language  = {en}
}
@article{MuessigLisinetskayaDewhurstetal.2020,
  author    = {Muessig, Jonas H. and Lisinetskaya, Polina and Dewhurst, Rian D. and Bertermann, R{\"u}diger and Thaler, Melanie and Mitric, Roland and Braunschweig, Holger},
  title     = {Tetraiododiborane(4) (B\(_2\)I\(_4\)) is a Polymer based on sp\(^3\) Boron in the Solid State},
  series = {Angewandte Chemie International Edition},
  volume    = {59},
  journal   = {Angewandte Chemie International Edition},
  doi       = {10.1002/anie.201913590},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-209428},
  pages     = {5531-5535},
  year      = {2020},
  abstract  = {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.},
  language  = {en}
}
@article{SaalfrankFantuzziKupferetal.2020,
  author    = {Saalfrank, Christian and Fantuzzi, Felipe and Kupfer, Thomas and Ritschel, Benedikt and Hammond, Kai and Krummenacher, Ivo and Bertermann, R{\"u}diger and Wirthensohn, Raphael and Finze, Maik and Schmid, Paul and Engel, Volker and Engels, Bernd and Braunschweig, Holger},
  title     = {cAAC-stabilisierte 9,10-Diboraanthracene - offenschalige Singulettbiradikale},
  series = {Angewandte Chemie},
  volume    = {132},
  journal   = {Angewandte Chemie},
  number    = {43},
  doi       = {10.1002/ange.202008206},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218582},
  pages     = {19502 -- 19507},
  year      = {2020},
  abstract  = {Geringe HOMO-LUMO-Abst{\"a}nde und eine hohe Ladungstr{\"a}germobilit{\"a}t pr{\"a}destinieren die h{\"o}heren Acene f{\"u}r Anwendungen im Bereich der Organoelektronik. Die Leistungsf{\"a}higkeit derartiger Verbindungen steigt hierbei dramatisch mit der Anzahl anellierter Benzolringe. Gr{\"o}ßere Acenmengen sind synthetisch bisher jedoch nur f{\"u}r Acene bis Heptacen verl{\"a}sslich zug{\"a}nglich. Theoretischen Studien zufolge besitzen (Oligo)acene offenschalige Singulettbiradikal- und (Poly)acene polyradikalische Grundzust{\"a}nde. Eindeutige experimentelle Belege f{\"u}r diese Vorhersagen sind hingegen {\"a}ußerst selten. Durch den Einbau von zwei Boratomen in das Anthracengrundger{\"u}st konnten wir den HOMO-LUMO-Abstand von Acenen dramatisch verringern und zwar ohne die Notwendigkeit einer Ausweitung des konjugierten π-Systems. Stabilisierung der Borzentren durch cyclische (Alkyl)(amino)carbene lieferte hierbei neutrale 9,10-Diboraanthracene mit disjunkten, offenschaligen Singulettbiradikal-Grundzust{\"a}nden.},
  language  = {en}
}
@article{GoettelGaoDotzaueretal.2020,
  author    = {Goettel, James T. and Gao, Haopeng and Dotzauer, Simon and Braunschweig, Holger},
  title     = {\(^{Me}\)CAAC=N\(^{-}\): A Cyclic (Alkyl)(Amino)Carbene Imino Ligand},
  series = {Chemistry - A European Journal},
  volume    = {26},
  journal   = {Chemistry - A European Journal},
  number    = {5},
  doi       = {10.1002/chem.201904715},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-212662},
  pages     = {1136-1143},
  year      = {2020},
  abstract  = {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.},
  language  = {en}
}
@article{SchmidtWernerArrowsmithetal.2020,
  author    = {Schmidt, Uwe and Werner, Luis and Arrowsmith, Merle and Deissenberger, Andrea and Hermann, Alexander and Hofmann, Alexander and Ullrich, Stefan and Mattock, James D. and Vargas, Alfredo and Braunschweig, Holger},
  title     = {trans-Selective Insertional Dihydroboration of a cis-Diborene: Synthesis of Linear sp\(^3\)-sp\(^2\)-sp\(^3\)-Triboranes and Subsequent Cationization},
  series = {Angewandte Chemie International Edition},
  volume    = {59},
  journal   = {Angewandte Chemie International Edition},
  number    = {1},
  doi       = {10.1002/anie.201911645},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-208090},
  pages     = {325-329},
  year      = {2020},
  abstract  = {The reaction of aryl- and amino(dihydro)boranes with dibora[2]ferrocenophane 1 leads to the formation 1,3-trans -dihydrotriboranes by formal hydrogenation and insertion of a borylene unit into the B=B bond. The aryltriborane derivatives undergo reversible photoisomerization to the cis -1,2-μ-H-3-hydrotriboranes, while hydride abstraction affords cationic triboranes, which represent the first doubly base-stabilized B3H4\(^+\) analogues.},
  language  = {en}
}