TY - JOUR A1 - Brückner, Tobias A1 - Fantuzzi, Felipe A1 - Stennett, Tom E. A1 - Krummenacher, Ivo A1 - Dewhurst, Rian D. A1 - Engels, Bernd A1 - Braunschweig, Holger T1 - Isolation of neutral, mono-, and dicationic B\(_2\)P\(_2\) rings by diphosphorus addition to a boron-boron triple bond JF - Angewandte Chemie International Edition N2 - The NHC-stabilised diboryne (B\(_2\)(SIDep)\(_2\); SIDep=1,3-bis(2,6-diethylphenyl)imidazolin-2-ylidene) undergoes a high-yielding P−P bond activation with tetraethyldiphosphine at room temperature to form a B\(_2\)P\(_2\) heterocycle via a diphosphoryldiborene by 1,2-diphosphination. The heterocycle can be oxidised to a radical cation and a dication, respectively, depending on the oxidant used and its counterion. Starting from the planar, neutral 1,3-bis(alkylidene)-1,3-diborata-2,4-diphosphoniocyclobutane, each oxidation step leads to decreased B−B distances and loss of planarity by cationisation. X-ray analyses in conjunction with DFT and CASSCF/NEVPT2 calculations reveal closed-shell singlet, butterfly-shaped structures for the NHC-stabilised dicationic B\(_2\)P\(_2\) rings, with their diradicaloid, planar-ring isomers lying close in energy. KW - inorganic chemistry KW - radicals KW - boron KW - density functional calculations KW - oxidation KW - phosphorus heterocycles Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256451 VL - 60 IS - 24 ER - TY - JOUR A1 - Brückner, Tobias A1 - Dewhurst, Rian D. A1 - Dellermann, Theresa A1 - Müller, Marcel A1 - Braunschweig, Holger T1 - Mild synthesis of diboryldiborenes by diboration of B–B triple bonds JF - Chemical Science N2 - A set of diboryldiborenes are prepared by the mild, catalyst-free, room-temperature diboration of the B–B triple bonds of doubly base-stabilized diborynes. Two of the product diboryldiborenes are found to be air- and water-stable in the solid state, an effect that is attributed to their high crystallinity and extreme insolubility in a wide range of solvents. KW - boron KW - diborenes KW - diboration KW - triple bonds KW - diborynes Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-186306 VL - 10 ER - TY - INPR A1 - Brückner, Tobias A1 - Arrowsmith, Merle A1 - Heß, Merlin A1 - Hammond, Kai A1 - Müller, Marcel A1 - Braunschweig, Holger T1 - Synthesis of fused B,N-heterocycles by alkyne cleavage, NHC ring-expansion and C-H activation at a diboryne T2 - Chemical Communications N2 - The addition of alkynes to a staturated N-heterocyclic carbene (NHC)-supported diboryne results in spontaneous cycloaddition, with complete B≡B and C≡C triple bond cleavage, NHC ring- expansion and activation of a variety of C-H bonds, leading to the formation of complex mixtures of fused B,N-heterocycles. KW - heterocycles KW - alkynes KW - boron KW - carbenes Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-184899 N1 - This is the pre-peer reviewed version of the following article: Chem. Commun., 2019,55, 6700-6703, which has been published in final form at doi:10.1039/C9CC02657F ER - TY - INPR A1 - Braunschweig, Holger A1 - Krummenacher, Ivo A1 - Lichtenberg, Crispin A1 - Mattock, James A1 - Schäfer, Marius A1 - Schmidt, Uwe A1 - Schneider, Christoph A1 - Steffenhagen, Thomas A1 - Ullrich, Stefan A1 - Vargas, Alfredo T1 - Dibora[2]ferrocenophane: A Carbene-Stabilized Diborene in a Strained cis-Configuration T2 - Angewandte Chemie, International Edition N2 - Unsaturated bridges that link the two cyclopentadienyl ligands together in strained ansa metallocenes are rare and limited to carbon-carbon double bonds. The synthesis and isolation of a strained ferrocenophane containing an unsaturated two-boron bridge, isoelectronic with a C=C double bond, was achieved by reduction of a carbene-stabilized 1,1’-bis(dihaloboryl)ferrocene. A combination of spectroscopic and electrochemical measurements as well as density functional theory (DFT) calculations was used to assess the influence of the unprecedented strained cis configuration on the optical and electrochemical properties of the carbene-stabilized diborene unit. Initial reactivity studies show that the dibora[2]ferrocenophane is prone to boron-boron double bond cleavage reactions. KW - Boron KW - Metallocenes KW - Metallocene KW - Bor KW - Diborane KW - density functional calculations KW - strained molecules KW - diborenes Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-141981 N1 - This is the pre-peer reviewed version of the following article: Angewandte Chemie, International Edition, Volume 56, Issue 3, 889–892, which has been published in final form at doi:10.1002/anie.201609601. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. ER - TY - JOUR A1 - Braunschweig, Holger A1 - Constantinidis, Philipp A1 - Dellermann, Theresa A1 - Ewing, William A1 - Fischer, Ingo A1 - Hess, Merlin A1 - Knight, Fergus A1 - Rempel, Anna A1 - Schneider, Christoph A1 - Ullrich, Stefan A1 - Vargas, Alfredo A1 - Woolins, Derek T1 - Highly Strained Heterocycles Constructed from Boron–Boron Multiple Bonds and Heavy Chalcogens JF - Angewandte Chemie, International Edition N2 - The reactions of a diborene with elemental selenium or tellurium are shown to afford a diboraselenirane or diboratellurirane, respectively. These reactions are reminiscent of the sequestration of subvalent oxygen and nitrogen in the formation of oxiranes and aziridines; however, such reactivity is not known between alkenes and the heavy chalcogens. Although carbon is too electronegative to affect the reduction of elements with lower relative electronegativity, the highly reducing nature of the B B double bond enables reactions with Se0 and Te0. The capacity of multiple bonds between boron atoms to donate electron density is highlighted in reactions where diborynes behave as nucleophiles, attacking one of the two Te atoms of diaryltellurides, forming salts consisting of diboratellurenium cations and aryltelluride anions. KW - Boron KW - Heterocycles KW - Multiple bonds KW - Selenium KW - Tellurium KW - Bor KW - Heterocyclische Verbindungen KW - Selen KW - Tellur Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-138237 N1 - This is the peer reviewed version of the following article: Angew. Chem. Int. Ed. 2016, 55, 5606–5609, which has been published in final form at 10.1002/anie.201601691. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. N1 - Accepted Version VL - 55 IS - 18 SP - 5606 EP - 5609 ER - TY - INPR A1 - Braunschweig, Holger A1 - Brückner, Tobias A1 - Deißenberger, Andrea A1 - Dewhurst, Rian A1 - Gackstatter, Annika A1 - Gärtner, Annalena A1 - Hofmann, Alexander A1 - Kupfer, Thomas A1 - Prieschl, Dominic A1 - Thiess, Torsten A1 - Wang, Sunewang Rixin T1 - Reaction of Dihalodiboranes(4) with N-Heterocyclic Silylenes: Facile Construction of 1-Aryl-2-Silyl-1,2-Diboraindanes T2 - Chemistry, A European Journal N2 - Dihalodiboranes(4) react with an N-heterocyclic silylene (NHSi) to generate NHSi-adducts of 1-aryl-2-silyl-1,2-diboraindanes as confirmed by X-ray crystallography, featuring the functionalization of both B–X (X = halogen) bonds and a C–H bond under mild conditions. Coordination of a third NHSi to the proposed 1,1-diaryl- 2,2-disilyldiborane(4) intermediates, generated by a two-fold B–X insertion, may be crucial for the C–H borylation that leads to the final products. Notably, our results demonstrate the first C–H borylation with a strong B–F bond activated by silylene insertion. KW - diborane KW - boron KW - silylenes KW - CH activation KW - bond activation KW - diboraindanes KW - diboranes KW - synthetic methods KW - borylation Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-153068 N1 - This is the pre-peer reviewed version of the following article: H. Braunschweig, T. Brückner, A. Deißenberger, R. D. Dewhurst, A. Gackstatter, A. Gärtner, A. Hofmann, T. Kupfer, D. Prieschl, T. Thiess, S. R. Wang, Reaction of Dihalodiboranes(4) with a N-Heterocyclic Silylene: Facile Construction of 1-Aryl-2-Silyl-1,2-Diboraindanes, Chem. Eur. J. 2017, 23, 9491., which has been published in final form at dx.doi.org/10.1002/chem.201702377. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving ER - TY - INPR A1 - Auerhammer, Dominic A1 - Arrowsmith, Merle A1 - Böhnke, Julian A1 - Braunschweig, Holger A1 - Dewhurst, Rian D. A1 - Kupfer, Thomas T1 - Brothers from Another Mother: a Borylene and its Dimer are Non-Interconvertible but Connected through Reactivity T2 - Chemical Science N2 - The self-stabilizing, tetrameric cyanoborylene [(cAAC)B(CN)]4 (I, cAAC = 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) and its diborene relative, [(cAAC)(CN)B=B(CN)(cAAC)] (II), both react with disulfides and diselenides to yield the corresponding cAAC-supported cyanoboron bis(chalcogenides). Furthermore, reactions of I or II with elemental sulfur and selenium in various stoichiometries provided access to a variety of cAAC- stabilized cyanoboron-chalcogen heterocycles, including a unique dithiaborirane, a diboraselenirane, 1,3-dichalcogena-2,4-diboretanes, 1,3,4-trichalcogena- 2,5-diborolanes and a rare six-membered 1,2,4,5-tetrathia-3,6-diborinane. Stepwise addition reactions and solution stability studies provided insights into the mechanism of these reactions and the subtle differences in reactivity observed between I and II. KW - borylenes KW - diborenes KW - boron KW - carbenes KW - chalcogens Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-157125 ER - TY - INPR A1 - Auerhammer, Dominic A1 - Arrowsmith, Merle A1 - Bissinger, Philipp A1 - Braunschweig, Holger A1 - Dellermann, Theresa A1 - Kupfer, Thomas A1 - Lenczyk, Carsten A1 - Roy, Dipak A1 - Schäfer, Marius A1 - Schneider, Christoph T1 - Increasing the Reactivity of Diborenes: Derivatization of NHC- Supported Dithienyldiborenes with Electron-Donor Groups T2 - Chemistry, A European Journal N2 - A series of NHC-supported 1,2-dithienyldiborenes was synthesized from the corresponding (dihalo)thienylborane NHC precursors. NMR and UV-vis spectroscopic data, as well as X-ray crystallographic analyses, were used to assess the electronic and steric influences on the B=B double bond of various NHCs and electron-donating substituents on the thienyl ligands. Crystallographic data showed that the degree of coplanarity of the diborene core and thienyl groups is highly dependent on the sterics of the substituents. Furthermore, any increase in the electron- donating ability of the substituents resulted in the destabilization of the HOMO and greater instability of the resulting diborenes. KW - diborenes KW - N-heterocyclic carbenes KW - electron donors KW - structural analysis KW - spectroscopy Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-155419 N1 - This is the pre-peer reviewed version of the following article: Auerhammer, D., Arrowsmith, M., Bissinger, P., Braunschweig, H., Dellermann, T., Kupfer, T., Lenczyk, C., Roy, D. K., Schäfer, M. and Schneider, C. (2017), Increasing the Reactivity of Diborenes: Derivatization of NHC-Supported Dithienyldiborenes with Electron-Donor Groups. Chem. Eur. J.. doi:10.1002/chem.201704669, which has been published in final form at doi:10.1002/chem.201704669. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. ER - TY - INPR A1 - Arrowsmith, Merle A1 - Mattock, James D. A1 - Böhnke, Julian A1 - Krummenacher, Ivo A1 - Vargas, Alfredo A1 - Braunschweig, Holger T1 - Direct access to a cAAC-supported dihydrodiborene and its dianion T2 - Chemical Communications N2 - The two-fold reduction of (cAAC)BHX\(_2\) (cAAC = 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene; X = Cl, Br) provides a facile, high-yielding route to the dihydrodiborene (cAAC)\(_2\)B\(_2\)H\(_2\). The (chloro)hydroboryl anion reduction intermediate was successfully isolated using a crown ether. Overreduction of the diborene to its dianion [(cAAC)\(_2\)B\(_2\)H\(_2\)]\(^{2−}\) causes a decrease in the B–B bond order whereas the B–C bond orders increase. KW - carbenes KW - diborenes KW - boron KW - main-group chemistry KW - diborynes Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-164276 N1 - This is the pre-peer reviewed version of the following article: Chemical Communications, 2018, 54, 4669-4672 which has been published at DOI: 10.1039/C8CC01580E ER - TY - INPR A1 - Arrowsmith, Merle A1 - Dömling, Michael A1 - Schmidt, Uwe A1 - Werner, Luis A1 - Castro, Abril C. A1 - Jiménez-Halla, J. Oscar C. A1 - Müssig, Jonas A1 - Prieschl, Dominic A1 - Braunschweig, Holger T1 - Spontaneous trans‐Selective Transfer Hydrogenation of Apolar B=B Double Bonds T2 - Angewandte Chemie, International Edition N2 - The transfer hydrogenation of NHC-supported diborenes with dimethylamine borane proceeds with high selectivity for the trans-1,2-dihydrodiboranes(6). DFT calculations suggest a stepwise proton-first-hydride-second reaction mechanism via an intermediate μ-hydrodiboronium dimethylaminoborate ion pair. KW - transfer hydrogenation KW - diborene KW - amine borane dehydrocoupling KW - diboranes KW - DFT mechanism Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-184874 N1 - This is the pre-peer reviewed version of the following article: M. Dömling, M. Arrowsmith, U. Schmidt, L. Werner, A. C. Castro, J. O. C. Jiménez-Halla, R. Bertermann, J. Müssig, D. Prieschl, H. Braunschweig, Angew. Chem. Int. Ed. 2019, 58, 9782. doi:10.1002/anie.201902656, which has been published in final form at https://doi.org/10.1002/anie.201902656. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. ER -