TY - INPR A1 - Braunschweig, Holger A1 - Krummenacher, Ivo A1 - Lichtenberg, Crispin A1 - Mattock, James A1 - Schäfer, Marius A1 - Schmidt, Uwe A1 - Schneider, Christoph A1 - Steffenhagen, Thomas A1 - Ullrich, Stefan A1 - Vargas, Alfredo T1 - Dibora[2]ferrocenophane: A Carbene-Stabilized Diborene in a Strained cis-Configuration T2 - Angewandte Chemie, International Edition N2 - Unsaturated bridges that link the two cyclopentadienyl ligands together in strained ansa metallocenes are rare and limited to carbon-carbon double bonds. The synthesis and isolation of a strained ferrocenophane containing an unsaturated two-boron bridge, isoelectronic with a C=C double bond, was achieved by reduction of a carbene-stabilized 1,1’-bis(dihaloboryl)ferrocene. A combination of spectroscopic and electrochemical measurements as well as density functional theory (DFT) calculations was used to assess the influence of the unprecedented strained cis configuration on the optical and electrochemical properties of the carbene-stabilized diborene unit. Initial reactivity studies show that the dibora[2]ferrocenophane is prone to boron-boron double bond cleavage reactions. KW - Boron KW - Metallocenes KW - Metallocene KW - Bor KW - Diborane KW - density functional calculations KW - strained molecules KW - diborenes Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-141981 N1 - This is the pre-peer reviewed version of the following article: Angewandte Chemie, International Edition, Volume 56, Issue 3, 889–892, which has been published in final form at doi:10.1002/anie.201609601. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. ER - TY - INPR A1 - Wang, Sunewang R. A1 - Arrowsmith, Merle A1 - Böhnke, Julian A1 - Braunschweig, Holger A1 - Dellermann, Theresa A1 - Dewhurst, Rian D. A1 - Kelch, Hauke A1 - Krummenacher, Ivo A1 - Mattock, James D. A1 - Müssig, Jonas H. A1 - Thiess, Torsten A1 - Vargas, Alfredo A1 - Zhang, Jiji T1 - Engineering a Small HOMO-LUMO Gap and Intramolecular B–B Hydroarylation by Diborene/Anthracene Orbital Intercalation T2 - Angewandte Chemie, International Edition N2 - The diborene 1 was synthesized by reduction of a mixture of 1,2-di-9-anthryl-1,2-dibromodiborane(4) (6) and trimethylphosphine with potassium graphite. The X-ray structure of 1 shows the two anthryl rings to be parallel and their π(C\(_{14}\)) systems perpendicular to the diborene π(B=B) system. This twisted conformation allows for intercalation of the relatively high-lying π(B=B) orbital and the low-lying π* orbital of the anthryl moiety with no significant conjugation, resulting in a small HOMO-LUMO gap (HLG) and ultimately an unprecedented anthryl B–B bond hydroarylation. The HLG of 1 was estimated to be 1.57 eV from the onset of the long wavelength band in its UV–vis absorption spectrum (THF, λ\(_{onset}\) = 788 nm). The oxidation of 1 with elemental selenium afforded diboraselenirane 8 in quantitative yield. By oxidative abstraction of one phosphine ligand by another equivalent of elemental selenium, the B–B and C\(^1\)–H bonds of 8 were cleaved to give the cyclic 1,9-diboraanthracene 9. KW - boron KW - small HOMO-LUMO gap KW - diborenes KW - borylation KW - hydroarylation Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148126 N1 - This is the pre-peer reviewed version of the following article: S. R. Wang, M. Arrowsmith, J. Böhnke, H. Braunschweig, T. Dellermann, R. D. Dewhurst, H. Kelch, I. Krummenacher, J. D. Mattock, J. H. Müssig, T. Thiess, A. Vargas, J. Zhang, Angew. Chem. Int. Ed. 2017, 56, 8009., which has been published in final form at DOI: 10.1002/anie.201704063. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. VL - 56 IS - 27 ER - TY - INPR A1 - 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 - Hermann, Alexander A1 - Cid, Jessica A1 - Mattock, James D. A1 - Dewhurst, Rian D. A1 - Krummenacher, Ivo A1 - Vargas, Alfredo A1 - Ingleson, Michael J. A1 - Braunschweig, Holger T1 - Diboryldiborenes: π‐Conjugated B\(_4\) Chains Isoelectronic to the Butadiene Dication T2 - Angewandte Chemie, International Edition N2 - sp\(^2\)–sp\(^3\) diborane species based on bis(catecholato)diboron and N-heterocyclic carbenes (NHCs) are subjected to catechol/bromide exchange selectively at the sp\(^3\) boron atom. The reduction of the resulting 1,1-dibromodiborane adducts led to reductive coupling and isolation of doubly NHC-stabilized 1,2-diboryldiborenes. These compounds are the first examples of molecules exhibiting pelectron delocalization over an all-boron chain. KW - diboranes KW - diborenes KW - N-heterocyclic carbenes KW - boron chains KW - pi-conjugation Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-167977 N1 - This is the pre-peer reviewed version of the following article: A. Hermann, J. Cid, J. D. Mattock, R. D. Dewhurst, I. Krummenacher, A. Vargas, M. J. Ingleson, H. Braunschweig, Angew. Chem. Int. Ed. 2018, 57, 10091, which has been published in final form at https://doi.org/10.1002/anie.201805394. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. ER -