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  - Arrowsmith, Merle
A1  - Böhnke, Julian
A1  - Braunschweig, Holger
A1  - Celik, Mehmet
A1  - Claes, Christina
A1  - Ewing, William
A1  - Krummenacher, Ivo
A1  - Lubitz, Katharina
A1  - Schneider, Christoph
T1  - Neutral Diboron Analogues of Archetypal Aromatic Species by Spontaneous Cycloaddition
N2  - Among the numerous routes organic chemists have developed to synthesize benzene derivatives and heteroaro- matic compounds, transition-metal-catalyzed cycloaddition reactions are the most elegant. In contrast, cycloaddition reactions of heavier alkene and alkyne analogues, though limited in scope, proceed uncatalyzed. In this work we present the first spontaneous cycloaddition reactions of lighter alkene and alkyne analogues. Selective addition of unactivated alkynes to boron–boron multiple bonds under ambient con- ditions yielded diborocarbon equivalents of simple aromatic hydrocarbons, including the first neutral 6p-aromatic dibora- benzene compound, a 2 p-aromatic triplet biradical 1,3-dibor- ete, and a phosphine-stabilized 2 p-homoaromatic 1,3-dihydro- 1,3-diborete. DFT calculations suggest that all three com- pounds are aromatic and show frontier molecular orbitals matching those of the related aromatic hydrocarbons, C6H6 and C4H42+, and homoaromatic C4H5+.
KW  - Aromaticity
KW  - Biradicals
KW  - Boron
KW  - Cycloaddition
KW  - Multiple bonds
KW  - Diborane
KW  - Cycloaddition
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-142500
ER  -