TY  - INPR
A1  - Stennett, Tom
A1  - Mattock, James
A1  - Vollert, Ivonne
A1  - Vargas, Alfredo
A1  - Braunschweig, Holger
T1  - Unsymmetrical, Cyclic Diborenes and Thermal Rearrangement to a Borylborylene
T2  - Angewandte Chemie, International Edition
N2  - Cyclic diboranes(4) based on a chelating monoanionic, benzylphosphine linker were prepared by boron-silicon exchange between arylsilanes and B\(_2\)Br\(_4\). Coordination of Lewis bases to the remaining sp\(^2\) boron atom yielded unsymmetrical sp\(^3\)-sp\(^3\) diboranes, which were reduced with KC\(_8\) to their corresponding trans-diborenes. These compounds were studied by a combination of spectroscopic methods, X-ray diffraction and DFT calculations. PMe\(_3\)-stabilized diborene 6 was found to undergo thermal rearrangement to gem- diborene 8. DFT calculations on 8 reveal a polar boron-boron bond, and indicate that the compound is best described as a borylborylene.
KW  - boron
KW  - borylene
KW  - multiple bonds
KW  - rearrangement
KW  - DFT calculations
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-160258
N1  - This is the pre-peer reviewed version of the following article: T. E. Stennett, J. D. Mattock, I. Vollert, A. Vargas, H. Braunschweig, Angew. Chem. Int. Ed. 2018, 57, 4098., which has been published in final form at DOI: 10.1002/anie.201800671. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
VL  - 57
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  - Böhnke, Julian
A1  - Braunschweig, Holger
A1  - Jiménez-Halla, Oscar
A1  - Krummenacher, Ivo
A1  - Stennett, Tom E.
T1  - Half-Sandwich Complexes of an Extremely Electron-Donating, Re-dox-Active η\(^6\)-Diborabenzene Ligand
T2  - Journal of the American Chemical Society
N2  - The heteroarene 1,4-bis(CAAC)-1,4-diborabenzene (1; CAAC = cyclic (alkyl)(amino)carbene) reacts with [(MeCN)\(_3\)M(CO)\(_3\)] (M = Cr, Mo, W) to yield half-sandwich complexes of the form [(η\(^6\)-diborabenzene)M(CO)\(_3\)] (M = Cr (2), Mo (3), W (4)). Investigation of the new complexes with a combination of X-ray diffraction, spectroscopic methods and DFT calculations shows that ligand 1 is a remarkably strong electron donor. In particular, [(η\(^6\)-arene)M(CO)\(_3\)] complexes of this ligand display the lowest CO stretching frequencies yet observed for this class of complex. Cyclic voltammetry on complexes 2-4 revealed one reversi- ble oxidation and two reversible reduction events in each case, with no evidence of ring-slippage of the arene to the η\(^4\) binding mode. Treatment of 4 with lithium metal in THF led to identification of the paramagnetic complex [(1)W(CO)\(_3\)]Li·2THF (5). Compound 1 can also be reduced in the absence of a transition metal to its dianion 1\(^{2–}\), which possesses a quinoid-type structure.
KW  - half-sandwich complexes
KW  - transition metal complex
KW  - boron
KW  - redox reactions
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-156766
N1  - This document is the unedited Author's version of a Submitted Work that was subsequently accepted for publication in Journal of the American Chemical Society, copyright © 2017 American Chemical Society after peer review. To access the final edited and published work see dx.doi.org/10.1021/jacs.7b12394.
ER  -