TY  - JOUR
A1  - Thiess, Torsten
A1  - Mellerup, Soren  K.
A1  - Braunschweig, Holger
T1  - B–B Cleavage and Ring-Expansion of a 1,4,2,3-Diazadiborinine with N-Heterocyclic Carbenes
JF  - Chemistry - A European Journal
N2  - 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.
KW  - B,N-heterocylcles
KW  - B-B bond activation
KW  - diazadiborinines
KW  - NHCs
KW  - ring-expansion reactions
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-206173
VL  - 25
IS  - 59
ER  - 
TY  - INPR
A1  - Englert, Lukas
A1  - Stoy, Andreas
A1  - Arrowsmith, Merle
A1  - Müssig, Jonas H.
A1  - Thaler, Melanie
A1  - Deißenberger, Andrea
A1  - Häfner, Alena
A1  - Böhnke, Julian
A1  - Hupp, Florian
A1  - Seufert, Jens
A1  - Mies, Jan
A1  - Damme, Alexander
A1  - Dellermann, Theresa
A1  - Hammond, Kai
A1  - Kupfer, Thomas
A1  - Radacki, Krzysztof
A1  - Thiess, Torsten
A1  - Braunschweig, Holger
T1  - Stable Lewis Base Adducts of Tetrahalodiboranes: Synthetic Methods and Structural Diversity
T2  - Chemistry - A European Journal
N2  - A series of 22 new bis(phosphine), bis(carbene) and bis(isonitrile) tetrahalodiborane adducts has been synthesized, either by direct adduct formation with highly sensitive B2X4 precursors (X = Cl, Br, I) or by ligand exchange at stable B2X4(SMe2)2 precursors (X = Cl, Br) with labile dimethylsulfide ligands. The isolated compounds have been fully characterized using NMR spectroscopic, (C,H,N)- elemental and, for 20 of these compounds, X-ray crystallographic analysis, revealing an unexpected variation in the bonding motifs. Besides the classical B2X4L2 diborane(6) adducts, some of the more sterically demanding carbene ligands induce a halide displacement leading to the first halide-bridged monocationic diboron species, [B2X3L2]A (A = BCl4, Br, I). Furthermore, low-temperature 1:1 reactions of B2Cl4 with sterically demanding N-heterocyclic carbenes led to the formation of kinetically unstable mono-adducts, one of which was structurally characterized. A comparison of the NMR and structural data of new and literature-known bis-adducts shows several trends pertaining to the nature of the halides and the stereoelectronic properties of the Lewis bases employed.
KW  - diborane(6)
KW  - Lewis-base adducts
KW  - ligand exchange
KW  - crystallography
KW  - NMR spectroscopy
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-184888
N1  - This is the pre-peer reviewed version of the following article: L. Englert, A. Stoy, M. Arrowsmith, J. H. Muessig, M. Thaler, A. Deißenberger, A. Häfner, J. Böhnke, F. Hupp, J. Seufert, J. Mies, A. Damme, T. Dellermann, K. Hammond, T. Kupfer, K. Radacki, T. Thiess, H. Braunschweig, Chem. Eur. J. 2019, 25, 8612. https://doi.org/10.1002/chem.201901437, which has been published in final form at https://doi.org/10.1002/chem.201901437. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.
ER  -