TY  - JOUR
A1  - Ansell, Melvyn B.
A1  - Kostakis, George E.
A1  - Braunschweig, Holger
A1  - Navarro, Oscar
A1  - Spencer, John
T1  - Synthesis of functionalized hydrazines: facile homogeneous (N-heterocyclic carbene)-palladium(0)-catalyzed diboration and silaboration of azobenzenes
JF  - Advanced Synthesis & Catalysis
N2  - The bis(N-heterocyclic carbene)(diphenylacetylene)palladium complex Pd(ITMe)\(_2\)(PhCCPh)] (ITMe=1,3,4,5-tetramethylimidazol-2-ylidene) acts as a highly active pre-catalyst in the diboration and silaboration of azobenzenes to synthesize a series of novel functionalized hydrazines. The reactions proceed using commercially available diboranes and silaboranes under mild reaction conditions.
KW  - Palladium-catalyzed silaboration
KW  - B-B bond
KW  - molecular-structure
KW  - terminal alkynes
KW  - crystal-structure
KW  - alkenes
KW  - complexes
KW  - mechanism
KW  - boron
KW  - design
KW  - azobenzenes
KW  - dilaboration
KW  - N-heterocyclic carbenes
KW  - palladium
KW  - silaboration
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-186582
VL  - 358
IS  - 23
ER  - 
TY  - JOUR
A1  - Horrer, Günther
A1  - Krahfuß, Mirjam J.
A1  - Lubitz, Katharina
A1  - Krummenacher, Ivo
A1  - Braunschweig, Holger
A1  - Radius, Udo
T1  - N-Heterocyclic Carbene and Cyclic (Alkyl)(amino)carbene Complexes of Titanium(IV) and Titanium(III)
JF  - European Journal of Inorganic Chemistry
N2  - The reaction of one and two equivalents of the N ‐heterocyclic carbene IMes [IMes = 1,3‐bis(2,4,6‐trimethyl‐phenyl)imidazolin‐2‐ylidene] or the cyclic (alkyl)(amino)carbene cAAC\(^{Me}\) [cAAC\(^{Me}\) = 1‐(2,6‐diisopropyl‐phenyl)‐3,3,5,5‐tetra‐methylpyrrolidin‐2‐ylidene] with [TiCl\(_{4}\)] in n ‐hexane results in the formation of mono‐ and bis‐carbene complexes [TiCl\(_{4}\)(IMes)] 1 , [TiCl\(_{4}\)(IMes)2] 2 , [TiCl\(_{4}\)(cAAC\(^{Me}\))] 3 , and [TiCl\(_{4}\)(cAAC\(^{Me}\))\(_{2}\)] 4 , respectively. For comparison, the titanium(IV) NHC complex [TiCl\(_{4}\)(Ii Pr\(^{Me}\))] 5 (Ii Pr\(^{Me}\) = 1,3‐diisopropyl‐4,5‐dimethyl‐imidazolin‐2‐ylidene) has been synthesized and structurally characterized. The reaction of [TiCl\(_{4}\)(IMes)] 1 with PMe\(_{3}\) affords the mixed substituted complex [TiCl\(_{4}\)(IMes)(PMe\(_{3}\))] 6 . The reactions of [TiCl\(_{3}\)(THF)\(_{3}\)] with two equivalents of the carbenes IMes and cAAC\(^{Me}\) in n ‐hexane lead to the clean formation of the titanium(III) complexes [TiCl\(_{3}\)(IMes)\(_{2}\)] 7 and [TiCl\(_{3}\)(cAAC\(^{Me}\))\(_{2}\)] 8 . Compounds 1 –8 have been completely characterized by elemental analysis, IR and multinuclear NMR spectroscopy and for 2 –5 , 7 and 8 by X‐ray diffraction. Magnetometry in solution, EPR and UV/Vis spectroscopy and DFT calculations performed on 7 and 8 are indicative of a predominantly metal‐centered d\(^{1}\)‐radical in both cases.
KW  - N-heterocyclic carbenes
KW  - carbene ligands
KW  - Titanium
KW  - structure elucidation
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-208725
VL  - 2020
IS  - 3
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  - 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  -