TY  - JOUR
A1  - Lenczyk, Carsten
A1  - Roy, Dipak Kumar
A1  - Oberdorf, Kai
A1  - Nitsch, Jörn
A1  - Dewhurst, Rian D.
A1  - Radacki, Krzysztof
A1  - Halet, Jean-François
A1  - Marder, Todd B.
A1  - Bickelhaupt, Matthias
A1  - Braunschweig, Holger
T1  - Toward Transition‐Metal‐Templated Construction of Arylated B\(_{4}\) Chains by Dihydroborane Dehydrocoupling
JF  - Chemistry - A European Journal
N2  - The reactivity of a diruthenium tetrahydride complex towards three selected dihydroboranes was investigated. The use of [DurBH\(_{2}\)] (Dur=2,3,5,6‐Me\(_{4}\)C\(_{6}\)H) and [(Me\(_{3}\)Si)\(_{2}\)NBH\(_{2}\)] led to the formation of bridging borylene complexes of the form [(Cp\(^{*}\)RuH)\(_{2}\)BR] (Cp\(^{*}\)=C\(_{5}\)Me\(_{5}\); 1 a: R=Dur; 1 b: R=N(SiMe\(_{3}\))\(_{2}\)) through oxidative addition of the B−H bonds with concomitant hydrogen liberation. Employing the more electron‐deficient dihydroborane [3,5‐(CF\(_{3}\))\(_{2}\)‐C\(_{6}\)H\(_{3}\)BH\(_{2}\)] led to the formation of an anionic complex bearing a tetraarylated chain of four boron atoms, namely Li(THF)\(_{4}\)[(Cp\(^{*}\)Ru)\(_{2}\)B\(_{4}\)H\(_{5}\)(3,5‐(CF\(_{3}\))\(_{2}\)C\(_{6}\)H\(_{3}\))\(_{4}\)] (4), through an unusual, incomplete threefold dehydrocoupling process. A comparative theoretical investigation of the bonding in a simplified model of 4 and the analogous complex nido‐[1,2(Cp\(^{*}\)Ru)\(_{2}\)(μ‐H)B\(_{4}\)H\(_{9}\)] (I) indicates that there appear to be no classical σ‐bonds between the boron atoms in complex I, whereas in the case of 4 the B\(_{4}\) chain better resembles a network of three B−B σ bonds, the central bond being significantly weaker than the other two.
KW  - transition metal
KW  - B−H activation
KW  - boron
KW  - dehydrocoupling
KW  - ruthenium
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-214324
VL  - 25
IS  - 72
ER  - 
TY  - JOUR
A1  - Lenczyk, Carsten
A1  - Roy, Dipak Kumar
A1  - Nitsch, Jörn
A1  - Radacki, Krzysztof
A1  - Rauch, Florian
A1  - Dewhurst, Rian D.
A1  - Bickelhaupt, F. Matthias
A1  - Marder, Todd B.
A1  - Braunschweig, Holger
T1  - Steric Effects Dictate the Formation of Terminal Arylborylene Complexes of Ruthenium from Dihydroboranes
JF  - Chemistry - A European Journal
N2  - The steric and electronic properties of aryl substituents in monoaryl borohydrides (Li[ArBH\(_3\)]) and dihydroboranes were systematically varied and their reactions with [Ru(PCy\(_3\))\(_2\)HCl(H\(_2\))] (Cy: cyclohexyl) were studied, resulting in bis(σ)‐borane or terminal borylene complexes of ruthenium. These variations allowed for the investigation of the factors involved in the activation of dihydroboranes in the synthesis of terminal borylene complexes. The complexes were studied by multinuclear NMR spectroscopy, mass spectrometry, X‐ray diffraction analysis, and density functional theory (DFT) calculations. The experimental and computational results suggest that the ortho‐substitution of the aryl groups is necessary for the formation of terminal borylene complexes.
KW  - Arylborylene Complexes
KW  - Ruthenium
KW  - Dihydroboranes
KW  - boranes
KW  - borohydrides
KW  - borylenes
KW  - steric effects
KW  - sigma boranes
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-219537
SN  - 1521-3765
VL  - 25
IS  - 59
ER  - 
TY  - JOUR
A1  - Lindl, Felix
A1  - Guo, Xueying
A1  - Krummenacher, Ivo
A1  - Rauch, Florian
A1  - Rempel, Anna
A1  - Paprocki, Valerie
A1  - Dellermann, Theresa
A1  - Stennett, Tom E.
A1  - Lamprecht, Anna
A1  - Brückner, Tobias
A1  - Radacki, Krzysztof
A1  - Bélanger-Chabot, Guillaume
A1  - Marder, Todd B.
A1  - Lin, Zhenyang
A1  - Braunschweig, Holger
T1  - Rethinking Borole Cycloaddition Reactivity
JF  - Chemistry—A European Journal
N2  - Boroles are attracting broad interest for their myriad and diverse applications, including in synthesis, small molecule activation and functional materials. Their properties and reactivity are closely linked to the cyclic conjugated diene system, which has been shown to participate in cycloaddition reactions, such as the Diels-Alder reaction with alkynes. The reaction steps leading to boranorbornadienes, borepins and tricyclic boracyclohexenes from the thermal reaction of boroles with alkynes are seemingly well understood as judged from the literature. Herein, we question the long-established mechanistic picture of pericyclic rearrangements by demonstrating that seven-membered borepins (i. e., heptaphenylborepin and two derivatives substituted with a thienyl and chloride substituent on boron) exist in a dynamic equilibrium with the corresponding bicyclic boranorbornadienes, the direct Diels-Alder products, but are not isolable products from the reactions. Heating gradually converts the isomeric mixtures into fluorescent tricyclic boracyclohexenes, the most stable isomers in the series. Results from mechanistic DFT calculations reveal that the tricyclic compounds derive from the boranorbornadienes and not the borepins, which were previously believed to be intermediates in purely pericyclic processes.
KW  - pericyclic reaction
KW  - Boron
KW  - computational chemistry
KW  - isomer
KW  - isomerization
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256888
VL  - 27
IS  - 43
ER  -