@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}
}
@article{ArrowsmithBoehnkeBraunschweigetal.2016,
  author    = {Arrowsmith, Merle and B{\"o}hnke, Julian and Braunschweig, Holger and Celik, Mehmet and Dellermann, Theresa and Hammond, Kai},
  title     = {Uncatalyzed Hydrogenation of First-Row Main Group Multiple Bonds},
  series = {Chemistry, A European Journal},
  volume    = {22},
  journal   = {Chemistry, A European Journal},
  number    = {48},
  doi       = {10.1002/chem.201604094},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-139364},
  pages     = {17169 -- 17172},
  year      = {2016},
  abstract  = {Room temperature hydrogenation of an SIDep-stabilized diboryne (SIDep = 1,3-bis(diethylphenyl)-4,5-dihydroimidazol-2-ylidene) and a CAAC-supported diboracumulene (CAAC = 1-(2,6- diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) provided the first selective route to the corresponding 1,2-dihydrodiborenes. DFT calculations showed an overall exothermic (ΔG = 19.4 kcal mol\(^{-1}\) two-step asynchronous H\(_2\) addition mechanism proceeding via a bridging hydride.},
  subject      = {Diborane},
  language  = {en}
}
@article{ArrowsmithBoehnkeBraunschweigetal.2016,
  author    = {Arrowsmith, Merle and B{\"o}hnke, Julian and Braunschweig, Holger and Celik, Mehmet and Claes, Christina and Ewing, William and Krummenacher, Ivo and Lubitz, Katharina and Schneider, Christoph},
  title     = {Neutral Diboron Analogues of Archetypal Aromatic Species by Spontaneous Cycloaddition},
  series = {Angewandte Chemie, International Edition},
  volume    = {55},
  journal   = {Angewandte Chemie, International Edition},
  doi       = {10.1002/anie.201602384},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-138226},
  pages     = {11271-11275},
  year      = {2016},
  abstract  = {Among the numerous routes organic chemists have developed to synthesize benzene derivatives and heteroaro- matic compounds, transition-metal-catalyzed cycloaddition reactions are the most elegant. In contrast, cycloaddition reactions of heavier alkene and alkyne analogues, though limited in scope, proceed uncatalyzed. In this work we present the first spontaneous cycloaddition reactions of lighter alkene and alkyne analogues. Selective addition of unactivated alkynes to boron-boron multiple bonds under ambient con- ditions yielded diborocarbon equivalents of simple aromatic hydrocarbons, including the first neutral 6 π-aromatic dibora- benzene compound, a 2  π-aromatic triplet biradical 1,3-dibor- ete, and a phosphine-stabilized 2  π-homoaromatic 1,3-dihydro- 1,3-diborete. DFT calculations suggest that all three com- pounds are aromatic and show frontier molecular orbitals matching those of the related aromatic hydrocarbons, C\(_6\)H\(_6\) and C\(_4\)H\(_4\)\(^{2+}\), and homoaromatic C\(_4\)H\(_5\)\(^+\).},
  language  = {en}
}
@article{BraunschweigConstantinidisDellermannetal.2016,
  author    = {Braunschweig, Holger and Constantinidis, Philipp and Dellermann, Theresa and Ewing, William and Fischer, Ingo and Hess, Merlin and Knight, Fergus and Rempel, Anna and Schneider, Christoph and Ullrich, Stefan and Vargas, Alfredo and Woolins, Derek},
  title     = {Highly Strained Heterocycles Constructed from Boron-Boron Multiple Bonds and Heavy Chalcogens},
  series = {Angewandte Chemie, International Edition},
  volume    = {55},
  journal   = {Angewandte Chemie, International Edition},
  number    = {18},
  doi       = {10.1002/anie.201601691},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-138237},
  pages     = {5606 -- 5609},
  year      = {2016},
  abstract  = {The reactions of a diborene with elemental selenium or tellurium are shown to afford a diboraselenirane or diboratellurirane, respectively. These reactions are reminiscent of the sequestration of subvalent oxygen and nitrogen in the formation of oxiranes and aziridines; however, such reactivity is not known between alkenes and the heavy chalcogens. Although carbon is too electronegative to affect the reduction of elements with lower relative electronegativity, the highly reducing nature of the B B double bond enables reactions with Se0 and Te0. The capacity of multiple bonds between boron atoms to donate electron density is highlighted in reactions where diborynes behave as nucleophiles, attacking one of the two Te atoms of diaryltellurides, forming salts consisting of diboratellurenium cations and aryltelluride anions.},
  subject      = {Bor},
  language  = {en}
}
@article{ArnoldBraunschweigGruss2011,
  author    = {Arnold, Thomas and Braunschweig, Holger and Gruss, Katrin},
  title     = {cyclo-Tri-mu-oxido-tris{[(eta 5,eta 5)-1,2-bis(cyclopentadienyl)-1,1,2,2-tetramethyldisilane]zirconium(IV)}: a trimeric disila-bridged oxidozirconocene},
  series = {Acta Crystallographica Section E: metal-organic compounds},
  volume    = {67},
  journal   = {Acta Crystallographica Section E: metal-organic compounds},
  doi       = {10.1107/S1600536811007094},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-134802},
  pages     = {M391-sup-23},
  year      = {2011},
  abstract  = {The title compound, [Zr(3)(C(14)H(20)Si(2))(3)O(3)], consists of three disila-bridged zirconocene units, which are connected via an oxide ligand, forming a nearly planar six-membered ring with a maximum displacement of 0.0191 (8) A. The compound was isolated as a by-product from a mixture of [(C(5)H(4)SiMe(2))(2)ZrCl(2)] and Li[AlH(4)] in Et(2)O.},
  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{HeRauchFriedrichetal.2019,
  author    = {He, Jiang and Rauch, Florian and Friedrich, Alexandra and Sieh, Daniel and Ribbeck, Tatjana and Krummenacher, Ivo and Braunschweig, Holger and Finze, Maik and Marder, Todd B.},
  title     = {N-Heterocyclic Olefins as Electron Donors in Combination with Triarylborane Acceptors: Synthesis, Optical and Electronic Properties of D-π-A Compounds},
  series = {Chemistry - A European Journal},
  volume    = {25},
  journal   = {Chemistry - A European Journal},
  doi       = {10.1002/chem.201903118},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-204690},
  pages     = {13777-13784},
  year      = {2019},
  abstract  = {N-heterocyclic olefins (NHOs), relatives of N-heterocyclic carbenes (NHCs), exhibit high nucleophilicity and soft Lewis basic character. To investigate their π-electron donating ability, NHOs were attached to triarylborane π-acceptors (A) giving donor (D)-π-A compounds 1-3. In addition, an enamine π-donor analogue (4) was synthesized for comparison. UV-visible absorption studies show a larger red shift for the NHO-containing boranes than for the enamine analogue, a relative of cyclic (alkyl)(amino) carbenes (CAACs). Solvent-dependent emission studies indicate that 1-4 have moderate intramolecular charge-transfer (ICT) behavior. Electrochemical investigations reveal that the NHO-containing boranes have extremely low reversible oxidation potentials (e.g., for 3, \(E^{ox}_{1/2}\) =-0.40 V vs. ferrocene/ferrocenium, Fc/Fc\(^+\), in THF). Time-dependent (TD) DFT calculations show that the HOMOs of 1-3 are much more destabilized than that of the enamine-containing 4, which confirms the stronger donating ability of NHOs.},
  language  = {en}
}
@article{BoehnkeDellermannCeliketal.2018,
  author    = {B{\"o}hnke, Julian and Dellermann, Theresa and Celik, Mehmet Ali and Krummenacher, Ivo and Dewhurst, Rian D. and Demeshko, Serhiy and Ewing, William C. and Hammond, Kai and Heß, Merlin and Bill, Eckhard and Welz, Eileen and R{\"o}hr, Merle I. S. and Mitric, Roland and Engels, Bernd and Meyer, Franc and Braunschweig, Holger},
  title     = {Isolation of diborenes and their 90°-twisted diradical congeners},
  series = {Nature Communications},
  volume    = {9},
  journal   = {Nature Communications},
  number    = {Article number: 1197},
  doi       = {10.1038/s41467-018-02998-3},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-160431},
  year      = {2018},
  abstract  = {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.},
  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{ThiessMellerupBraunschweig2019,
  author    = {Thiess, Torsten and Mellerup, Soren K. and Braunschweig, Holger},
  title     = {B-B Cleavage and Ring-Expansion of a 1,4,2,3-Diazadiborinine with N-Heterocyclic Carbenes},
  series = {Chemistry - A European Journal},
  volume    = {25},
  journal   = {Chemistry - A European Journal},
  number    = {59},
  doi       = {10.1002/chem.201903259},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-206173},
  pages     = {13572-13578},
  year      = {2019},
  abstract  = {A 1,4,2,3-diazadiborinine derivative was found to form Lewis adducts with strong two-electron donors such as N-heterocyclic and cyclic (alkyl)(amino)carbenes. Depending on the donor, some of these Lewis pairs are thermally unstable, converting to sole B,N-embedded products upon gentle heating. The products of these reactions, which have been fully characterized by NMR spectroscopy, elemental analysis, and single-crystal X-ray diffraction, were identified as B,N-heterocycles with fused 1,5,2,4-diazadiborepine and 1,4,2-diazaborinine rings. Computational modelling of the reaction mechanism provides insight into the formation of these unique structures, suggesting that a series of B-H, C-N, and B-B bond activation steps are responsible for these "intercalation" reactions between the 1,4,2,3-diazadiborinine and NHCs.},
  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{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{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{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{RauchFuchsFriedrichetal.2020,
  author    = {Rauch, Florian and Fuchs, Sonja and Friedrich, Alexandra and Sieh, Daniel and Krummenacher, Ivo and Braunschweig, Holger and Finze, Maik and Marder, Todd B.},
  title     = {Highly Stable, Readily Reducible, Fluorescent, Trifluoromethylated 9-Borafluorenes},
  series = {Chemistry - A European Journal},
  volume    = {26},
  journal   = {Chemistry - A European Journal},
  number    = {56},
  doi       = {10.1002/chem.201905559},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218390},
  pages     = {12794 -- 12808},
  year      = {2020},
  abstract  = {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.},
  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{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{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}
}
@article{HuangWangDewhurstetal.2020,
  author    = {Huang, Zhenguo and Wang, Suning and Dewhurst, Rian D. and Ignat'ev, Nikolai V. and Finze, Maik and Braunschweig, Holger},
  title     = {Boron: Its Role in Energy-Related Processes and Applications},
  series = {Angewandte Chemie International Edition},
  volume    = {59},
  journal   = {Angewandte Chemie International Edition},
  number    = {23},
  doi       = {10.1002/anie.201911108},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218514},
  pages     = {8800 -- 8816},
  year      = {2020},
  abstract  = {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.},
  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{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{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{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{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{HattoriMichailSchmiedeletal.2019,
  author    = {Hattori, Yohei and Michail, Evripidis and Schmiedel, Alexander and Moos, Michael and Holzapfel, Marco and Krummenacher, Ivo and Braunschweig, Holger and M{\"u}ller, Ulrich and Pflaum, Jens and Lambert, Christoph},
  title     = {Luminescent Mono-, Di-, and Tri-radicals: Bridging Polychlorinated Triarylmethyl Radicals by Triarylamines and Triarylboranes},
  series = {Chemistry - A European Journal},
  volume    = {25},
  journal   = {Chemistry - A European Journal},
  number    = {68},
  doi       = {10.1002/chem.201903007},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-208162},
  pages     = {15463-15471},
  year      = {2019},
  abstract  = {Up to three polychlorinated pyridyldiphenylmethyl radicals bridged by a triphenylamine carrying electron withdrawing (CN), neutral (Me), or donating (OMe) groups were synthesized and analogous radicals bridged by tris(2,6-dimethylphenyl)borane were prepared for comparison. All compounds were as stable as common closed-shell organic compounds and showed significant fluorescence upon excitation. Electronic, magnetic, absorption, and emission properties were examined in detail, and experimental results were interpreted using DFT calculations. Oxidation potentials, absorption and emission energies could be tuned depending on the electron density of the bridges. The triphenylamine bridges mediated intramolecular weak antiferromagnetic interactions between the radical spins, and the energy difference between the high spin and low spin states was determined by temperature dependent ESR spectroscopy and DFT calculations. The fluorescent properties of all radicals were examined in detail and revealed no difference for high and low spin states which facilitates application of these dyes in two-photon absorption spectroscopy and OLED devices.},
  language  = {en}
}
@article{LenczykRoyOberdorfetal.2019,
  author    = {Lenczyk, Carsten and Roy, Dipak Kumar and Oberdorf, Kai and Nitsch, J{\"o}rn and Dewhurst, Rian D. and Radacki, Krzysztof and Halet, Jean-Fran{\c{c}}ois and Marder, Todd B. and Bickelhaupt, Matthias and Braunschweig, Holger},
  title     = {Toward Transition-Metal-Templated Construction of Arylated B\(_{4}\) Chains by Dihydroborane Dehydrocoupling},
  series = {Chemistry - A European Journal},
  volume    = {25},
  journal   = {Chemistry - A European Journal},
  number    = {72},
  doi       = {10.1002/chem.201904772},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-214324},
  pages     = {16544-16549},
  year      = {2019},
  abstract  = {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.},
  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{LenczykRoyNitschetal.2019,
  author    = {Lenczyk, Carsten and Roy, Dipak Kumar and Nitsch, J{\"o}rn and Radacki, Krzysztof and Rauch, Florian and Dewhurst, Rian D. and Bickelhaupt, F. Matthias and Marder, Todd B. and Braunschweig, Holger},
  title     = {Steric Effects Dictate the Formation of Terminal Arylborylene Complexes of Ruthenium from Dihydroboranes},
  series = {Chemistry - A European Journal},
  volume    = {25},
  journal   = {Chemistry - A European Journal},
  number    = {59},
  issn      = {1521-3765},
  doi       = {10.1002/chem.201902890},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-219537},
  pages     = {13566-13571},
  year      = {2019},
  abstract  = {The steric and electronic properties of aryl substituents in monoaryl borohydrides (Li[ArBH\(_3\)]) and dihydroboranes were systematically varied and their reactions with [Ru(PCy\(_3\))\(_2\)HCl(H\(_2\))] (Cy: cyclohexyl) were studied, resulting in bis(σ)-borane or terminal borylene complexes of ruthenium. These variations allowed for the investigation of the factors involved in the activation of dihydroboranes in the synthesis of terminal borylene complexes. The complexes were studied by multinuclear NMR spectroscopy, mass spectrometry, X-ray diffraction analysis, and density functional theory (DFT) calculations. The experimental and computational results suggest that the ortho-substitution of the aryl groups is necessary for the formation of terminal borylene complexes.},
  language  = {en}
}
@article{Belanger‐ChabotBraunschweig2019,
  author    = {B{\´e}langer-Chabot, Guillaume and Braunschweig, Holger},
  title     = {Hexahalodiborate Dianions: A New Family of Binary Boron Halides},
  series = {Angewandte Chemie International Edition},
  volume    = {58},
  journal   = {Angewandte Chemie International Edition},
  number    = {40},
  doi       = {10.1002/anie.201906666},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-219688},
  pages     = {14270-14274},
  year      = {2019},
  abstract  = {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\(_4\)]\(^-\).},
  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}
}
@article{HermannFantuzziArrowsmithetal.2020,
  author    = {Hermann, Alexander and Fantuzzi, Felipe and Arrowsmith, Merle and Zorn, Theresa and Krummenacher, Ivo and Ritschel, Benedikt and Radacki, Krzysztof and Engels, Bernd and Braunschweig, Holger},
  title     = {Oxidation, Coordination, and Nickel-Mediated Deconstruction of a Highly Electron-Rich Diboron Analogue of 1,3,5-Hexatriene},
  series = {Angewandte Chemie, International Edition},
  volume    = {59},
  journal   = {Angewandte Chemie, International Edition},
  number    = {36},
  doi       = {10.1002/anie.202006131},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-240652},
  pages     = {15717-15725},
  year      = {2020},
  abstract  = {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).},
  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{RauchEndresFriedrichetal.2020,
  author    = {Rauch, Florian and Endres, Peter and Friedrich, Alexandra and Sieh, Daniel and H{\"a}hnel, Martin and Krummenacher, Ivo and Braunschweig, Holger and Finze, Maik and Ji, Lei and Marder, Todd B.},
  title     = {An Iterative Divergent Approach to Conjugated Starburst Borane Dendrimers},
  series = {Chemistry - A European Journal},
  volume    = {26},
  journal   = {Chemistry - A European Journal},
  number    = {57},
  doi       = {10.1002/chem.202001985},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218345},
  pages     = {12951 -- 12963},
  year      = {2020},
  abstract  = {Using a new divergent approach, conjugated triarylborane dendrimers were synthesized up to the 2nd generation. The synthetic strategy consists of three steps: 1) functionalization, via iridium catalyzed C-H borylation; 2) activation, via fluorination of the generated boronate ester with K[HF\(_{2}\)] or [N(nBu\(_{4}\))][HF\(_{2}\)]; and 3) expansion, via reaction of the trifluoroborate salts with aryl Grignard reagents. The concept was also shown to be viable for a convergent approach. All but one of the conjugated borane dendrimers exhibit multiple, distinct and reversible reduction potentials, making them potentially interesting materials for applications in molecular accumulators. Based on their photophysical properties, the 1st generation dendrimers exhibit good conjugation over the whole system. However, the conjugation does not increase further upon expansion to the 2nd generation, but the molar extinction coefficients increase linearly with the number of triarylborane subunits, suggesting a potential application as photonic antennas.},
  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{NeesKupferHofmannetal.2020,
  author    = {Nees, Samuel and Kupfer, Thomas and Hofmann, Alexander and Braunschweig, Holger},
  title     = {Planar Cyclopenten-4-yl Cations: Highly Delocalized π Aromatics Stabilized by Hyperconjugation},
  series = {Angewandte Chemie International Edition},
  volume    = {59},
  journal   = {Angewandte Chemie International Edition},
  number    = {42},
  doi       = {10.1002/anie.202009644},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218358},
  pages     = {18809 -- 18815},
  year      = {2020},
  abstract  = {Theoretical studies predicted the planar cyclopenten-4-yl cation to be a classical carbocation, and the highest-energy isomer of C\(_{5}\)H\(_{7}\)\(^{+}\). Hence, its existence has not been verified experimentally so far. We were now able to isolate two stable derivatives of the cyclopenten-4-yl cation by reaction of bulky alanes Cp\(^{R}\)AlBr\(_{2}\) with AlBr3. Elucidation of their (electronic) structures by X-ray diffraction and quantum chemistry studies revealed planar geometries and strong hyperconjugation interactions primarily from the C-Al σ bonds to the empty p orbital of the cationic sp\(^{2}\) carbon center. A close inspection of the molecular orbitals (MOs) and of the anisotropy of current (induced) density (ACID), as well as the evaluation of various aromaticity descriptors indicated distinct aromaticity for these cyclopenten-4-yl derivatives, which strongly contrasts the classical description of this system. Here, strong delocalization of π electrons spanning the whole carbocycle has been verified, thus providing rare examples of π aromaticity involving saturated sp\(^{3}\) carbon atoms.},
  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{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{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{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{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{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}
}