TY  - INPR
A1  - Böhnke, Julian
A1  - Dellermann, Theresa
A1  - Celik, Mehmet Ali
A1  - Krummenacher, Ivo
A1  - Dewhurst, Rian D.
A1  - Demeshko, Serhiy
A1  - Ewing, William C.
A1  - Hammond, Kai
A1  - Heß, Merlin
A1  - Bill, Eckhard
A1  - Welz, Eileen
A1  - Röhr, Merle I. S.
A1  - Mitric, Roland
A1  - Engels, Bernd
A1  - Meyer, Franc
A1  - Braunschweig, Holger
T1  - Isolation of diradical products of twisted double bonds
T2  - Nature Communications
N2  - Molecules containing multiple bonds between atoms—most often in the form of olefins—are ubiquitous in nature, commerce, and science, and as such have a huge impact on everyday life. Given their prominence, over the last few decades, frequent attempts have been made to perturb the structure and reactivity of multiply-bound species through bending and twisting. However, only modest success has been achieved in the quest to completely twist double bonds in order to homolytically cleave the associated π bond. Here, we present the isolation of double-bond-containing species based on boron, as well as their fully twisted diradical congeners, by the incorporation of attached groups with different electronic properties. The compounds comprise a structurally authenticated set of diamagnetic multiply-bound and diradical singly-bound congeners of the same class of compound.
KW  - diradicals
KW  - diborenes
KW  - carbenes
KW  - boron
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-160248
N1  - Submitted version of Julian Böhnke, Theresa Dellermann, Mehmet Ali Celik, Ivo Krummenacher, Rian D. Dewhurst, Serhiy Demeshko, William C. Ewing, Kai Hammond, Merlin Heß, Eckhard Bill, Eileen Welz, Merle I. S. Röhr, Roland Mitrić, Bernd Engels, Franc Meyer & Holger Braunschweig: Isolation of diborenes and their 90°-twisted diradical congeners. Nature Communications. Volume 9, Article number: 1197 (2018) doi:10.1038/s41467-018-02998-3
ER  - 
TY  - INPR
A1  - Schmidt, Uwe
A1  - Fantuzzi, Felipe
A1  - Arrowsmith, Merle
A1  - Hermann, Alexander
A1  - Prieschl, Dominic
A1  - Rempel, Anna
A1  - Engels, Bernd
A1  - Braunschweig, Holger
T1  - Tuneable reduction of cymantrenylboranes to diborenes or borylene-derived boratafulvenes
T2  - Chemical Communications
N2  - Whereas the reduction of N-heterocyclic carbene (NHC)-stabilised cymantrenyldibromoboranes, (NHC)BBr\(_2\)Cym, in benzene results in formation of the corresponding diborenes (NHC)\(_2\)B\(_2\)Cym\(_2\), a change of solvent to THF yields a borylene of the form (NHC)\(_2\)BCym, stabilised through its boratafulvene resonance form.
KW  - Borylene
KW  - Diborene
KW  - Boranes
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-222149
ER  - 
TY  - JOUR
A1  - Böhnke, Julian
A1  - Dellermann, Theresa
A1  - Celik, Mehmet Ali
A1  - Krummenacher, Ivo
A1  - Dewhurst, Rian D.
A1  - Demeshko, Serhiy
A1  - Ewing, William C.
A1  - Hammond, Kai
A1  - Heß, Merlin
A1  - Bill, Eckhard
A1  - Welz, Eileen
A1  - Röhr, Merle I. S.
A1  - Mitric, Roland
A1  - Engels, Bernd
A1  - Meyer, Franc
A1  - Braunschweig, Holger
T1  - Isolation of diborenes and their 90°-twisted diradical congeners
JF  - Nature Communications
N2  - Molecules containing multiple bonds between atoms—most often in the form of olefins—are ubiquitous in nature, commerce, and science, and as such have a huge impact on everyday life. Given their prominence, over the last few decades, frequent attempts have been made to perturb the structure and reactivity of multiply-bound species through bending and twisting. However, only modest success has been achieved in the quest to completely twist double bonds in order to homolytically cleave the associated π bond. Here, we present the isolation of double-bond-containing species based on boron, as well as their fully twisted diradical congeners, by the incorporation of attached groups with different electronic properties. The compounds comprise a structurally authenticated set of diamagnetic multiply-bound and diradical singly-bound congeners of the same class of compound.
KW  - chemical bonding
KW  - diradicals
KW  - organometallic chemistry
KW  - diborenes
KW  - carbenes
KW  - boron
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-160431
VL  - 9
IS  - Article number: 1197
ER  - 
TY  - JOUR
A1  - Weiser, Jonas
A1  - Cui, Jingjing
A1  - Dewhurst, Rian D.
A1  - Braunschweig, Holger
A1  - Engels, Bernd
A1  - Fantuzzi, Felipe
T1  - Structure and bonding of proximity‐enforced main‐group dimers stabilized by a rigid naphthyridine diimine ligand
JF  - Journal of Computational Chemistry
N2  - The development of ligands capable of effectively stabilizing highly reactive main‐group species has led to the experimental realization of a variety of systems with fascinating properties. In this work, we computationally investigate the electronic, structural, energetic, and bonding features of proximity‐enforced group 13–15 homodimers stabilized by a rigid expanded pincer ligand based on the 1,8‐naphthyridine (napy) core. We show that the redox‐active naphthyridine diimine (NDI) ligand enables a wide variety of structural motifs and element‐element interaction modes, the latter ranging from isolated, element‐centered lone pairs (e.g., E = Si, Ge) to cases where through‐space π bonds (E = Pb), element‐element multiple bonds (E = P, As) and biradical ground states (E = N) are observed. Our results hint at the feasibility of NDI‐E2 species as viable synthetic targets, highlighting the versatility and potential applications of napy‐based ligands in main‐group chemistry.
KW  - bond theory
KW  - computational chemistry
KW  - density functional calculations
KW  - main group elements
KW  - N ligands
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-312586
VL  - 44
IS  - 3
SP  - 456
EP  - 467
ER  - 
TY  - JOUR
A1  - Saalfrank, Christian
A1  - Fantuzzi, Felipe
A1  - Kupfer, Thomas
A1  - Ritschel, Benedikt
A1  - Hammond, Kai
A1  - Krummenacher, Ivo
A1  - Bertermann, Rüdiger
A1  - Wirthensohn, Raphael
A1  - Finze, Maik
A1  - Schmid, Paul
A1  - Engel, Volker
A1  - Engels, Bernd
A1  - Braunschweig, Holger
T1  - cAAC‐Stabilized 9,10‐diboraanthracenes—Acenes with Open‐Shell Singlet Biradical Ground States
JF  - Angewandte Chemie International Edition
N2  - Narrow HOMO–LUMO gaps and high charge‐carrier mobilities make larger acenes potentially high‐efficient materials for organic electronic applications. The performance of such molecules was shown to significantly increase with increasing number of fused benzene rings. Bulk quantities, however, can only be obtained reliably for acenes up to heptacene. Theoretically, (oligo)acenes and (poly)acenes are predicted to have open‐shell singlet biradical and polyradical ground states, respectively, for which experimental evidence is still scarce. We have now been able to dramatically lower the HOMO–LUMO gap of acenes without the necessity of unfavorable elongation of their conjugated π system, by incorporating two boron atoms into the anthracene skeleton. Stabilizing the boron centers with cyclic (alkyl)(amino)carbenes gives neutral 9,10‐diboraanthracenes, which are shown to feature disjointed, open‐shell singlet biradical ground states.
KW  - acenes
KW  - biradicals
KW  - bond Activation
KW  - boron
KW  - heterocycles
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-217795
VL  - 59
IS  - 43
SP  - 19338
EP  - 19343
ER  - 
TY  - JOUR
A1  - Brunecker, Carina
A1  - Müssig, Jonas H.
A1  - Arrowsmith, Merle
A1  - Fantuzzi, Felipe
A1  - Stoy, Andreas
A1  - Böhnke, Julian
A1  - Hofmann, Alexander
A1  - Bertermann, Rüdiger
A1  - Engels, Bernd
A1  - Braunschweig, Holger
T1  - Boranediyl‐ and Diborane(4)‐1,2‐diyl‐Bridged Platinum A‐Frame Complexes
JF  - Chemistry – A European Journal
N2  - Diplatinum A‐frame complexes with a bridging (di)boron unit in the apex position were synthesized in a single step by the double oxidative addition of dihalo(di)borane precursors at a bis(diphosphine)‐bridged Pt\(^{0}\)\(_{2}\) complex. While structurally analogous to well‐known μ‐borylene complexes, in which delocalized dative three‐center‐two‐electron M‐B‐M bonding prevails, theoretical investigations into the nature of Pt−B bonding in these A‐frame complexes show them to be rare dimetalla(di)boranes displaying two electron‐sharing Pt−B σ‐bonds. This is experimentally reflected in the low kinetic stability of these compounds, which are prone to loss of the (di)boron bridgehead unit.
KW  - boron
KW  - bonding
KW  - EDA-NOCV
KW  - oxidative addition
KW  - platinum
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-214707
VL  - 26
IS  - 39
SP  - 8518
EP  - 8523
ER  - 
TY  - JOUR
A1  - Brückner, Tobias
A1  - Fantuzzi, Felipe
A1  - Stennett, Tom E.
A1  - Krummenacher, Ivo
A1  - Dewhurst, Rian D.
A1  - Engels, Bernd
A1  - Braunschweig, Holger
T1  - Isolation of neutral, mono-, and dicationic B\(_2\)P\(_2\) rings by diphosphorus addition to a boron-boron triple bond
JF  - Angewandte Chemie International Edition
N2  - The NHC-stabilised diboryne (B\(_2\)(SIDep)\(_2\); SIDep=1,3-bis(2,6-diethylphenyl)imidazolin-2-ylidene) undergoes a high-yielding P−P bond activation with tetraethyldiphosphine at room temperature to form a B\(_2\)P\(_2\) heterocycle via a diphosphoryldiborene by 1,2-diphosphination. The heterocycle can be oxidised to a radical cation and a dication, respectively, depending on the oxidant used and its counterion. Starting from the planar, neutral 1,3-bis(alkylidene)-1,3-diborata-2,4-diphosphoniocyclobutane, each oxidation step leads to decreased B−B distances and loss of planarity by cationisation. X-ray analyses in conjunction with DFT and CASSCF/NEVPT2 calculations reveal closed-shell singlet, butterfly-shaped structures for the NHC-stabilised dicationic B\(_2\)P\(_2\) rings, with their diradicaloid, planar-ring isomers lying close in energy.
KW  - inorganic chemistry
KW  - radicals
KW  - boron
KW  - density functional calculations
KW  - oxidation
KW  - phosphorus heterocycles
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256451
VL  - 60
IS  - 24
ER  - 
TY  - JOUR
A1  - Saalfrank, Christian
A1  - Fantuzzi, Felipe
A1  - Kupfer, Thomas
A1  - Ritschel, Benedikt
A1  - Hammond, Kai
A1  - Krummenacher, Ivo
A1  - Bertermann, Rüdiger
A1  - Wirthensohn, Raphael
A1  - Finze, Maik
A1  - Schmid, Paul
A1  - Engel, Volker
A1  - Engels, Bernd
A1  - Braunschweig, Holger
T1  - cAAC‐stabilisierte 9,10‐Diboraanthracene – offenschalige Singulettbiradikale
JF  - Angewandte Chemie
N2  - Geringe HOMO-LUMO-Abstände und eine hohe Ladungsträgermobilität prädestinieren die höheren Acene für Anwendungen im Bereich der Organoelektronik. Die Leistungsfähigkeit derartiger Verbindungen steigt hierbei dramatisch mit der Anzahl anellierter Benzolringe. Größere Acenmengen sind synthetisch bisher jedoch nur für Acene bis Heptacen verlässlich zugänglich. Theoretischen Studien zufolge besitzen (Oligo)acene offenschalige Singulettbiradikal- und (Poly)acene polyradikalische Grundzustände. Eindeutige experimentelle Belege für diese Vorhersagen sind hingegen äußerst selten. Durch den Einbau von zwei Boratomen in das Anthracengrundgerüst konnten wir den HOMO-LUMO-Abstand von Acenen dramatisch verringern und zwar ohne die Notwendigkeit einer Ausweitung des konjugierten π-Systems. Stabilisierung der Borzentren durch cyclische (Alkyl)(amino)carbene lieferte hierbei neutrale 9,10-Diboraanthracene mit disjunkten, offenschaligen Singulettbiradikal-Grundzuständen.
KW  - Acene
KW  - Bindungsaktivierung
KW  - Biradikale
KW  - Bor
KW  - Heterocyclen
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-218582
VL  - 132
IS  - 43
SP  - 19502
EP  - 19507
ER  - 
TY  - JOUR
A1  - Rang, Maximilian
A1  - Fantuzzi, Felipe
A1  - Arrowsmith, Merle
A1  - Krummenacher, Ivo
A1  - Beck, Eva
A1  - Witte, Robert
A1  - Matler, Alexander
A1  - Rempel, Anna
A1  - Bischof, Tobias
A1  - Radacki, Krzysztof
A1  - Engels, Bernd
A1  - Braunschweig, Holger
T1  - Reduktion und Umlagerung eines Bor(I)‐Carbonylkomplexes
JF  - Angewandte Chemie
N2  - Bei der Einelektronenreduktion eines durch eine cyclisches (Alkyl)(amino)carben (CAAC) stabilisierten Arylborylen-Carbonylkomplexes erfolgt die Bildung eines dimeren Borylketyl-Radikalanions, bedingt durch eine intramolekulare Arylmigration zum CO Kohlenstoffatom. Computergestützte Analyse liefert Hinweise auf eine radikalanionische [(CAAC)B(CO)Ar]\(^{.-}\) Zwischenstufe. Weiterführende Reduktion des entstandenen Komplexes liefert ein hoch nukleophiles (Boranyliden)methanolat.
KW  - Biradikale
KW  - Bor-Carbonylkomplexe
KW  - Dichtefunktionalrechnungen
KW  - Reduktionen
KW  - Umlagerungen
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-224409
VL  - 133
IS  - 6
SP  - 3000
EP  - 3005
ER  - 
TY  - JOUR
A1  - Schmidt, Paul
A1  - Fantuzzi, Felipe
A1  - Klopf, Jonas
A1  - Schröder, Niklas B.
A1  - Dewhurst, Rian D.
A1  - Braunschweig, Holger
A1  - Engel, Volker
A1  - Engels, Bernd
T1  - Twisting versus delocalization in CAAC- and NHC-stabilized boron-based biradicals: the roles of sterics and electronics
JF  - Chemistry - A European Journal
N2  - Twisted boron-based biradicals featuring unsaturated C\(_2\)R\(_2\) (R=Et, Me) bridges and stabilization by cyclic (alkyl)(amino)carbenes (CAACs) were recently prepared. These species show remarkable geometrical and electronic differences with respect to their unbridged counterparts. Herein, a thorough computational investigation on the origin of their distinct electrostructural properties is performed. It is shown that steric effects are mostly responsible for the preference for twisted over planar structures. The ground-state multiplicity of the twisted structure is modulated by the σ framework of the bridge, and different R groups lead to distinct multiplicities. In line with the experimental data, a planar structure driven by delocalization effects is observed as global minimum for R=H. The synthetic elusiveness of C\(_2\)R\(_2\)-bridged systems featuring N-heterocyclic carbenes (NHCs) was also investigated. These results could contribute to the engineering of novel main group biradicals.
KW  - chemistry
KW  - radicals
KW  - ab initio calculations
KW  - boron
KW  - carbene ligands
KW  - density functional calculations
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256636
VL  - 27
IS  - 16
ER  - 
TY  - JOUR
A1  - Roy, Dipak Kumar
A1  - Tröster, Tobias
A1  - Fantuzzi, Felipe
A1  - Dewhurst, Rian D.
A1  - Lenczyk, Carsten
A1  - Radacki, Krzysztof
A1  - Pranckevicius, Conor
A1  - Engels, Bernd
A1  - Braunschweig, Holger
T1  - Isolation and Reactivity of an Antiaromatic s‐Block Metal Compound
JF  - Angewandte Chemie International Edition
N2  - The concepts of aromaticity and antiaromaticity have a long history, and countless demonstrations of these phenomena have been made with molecules based on elements from the p, d, and f blocks of the periodic table. In contrast, the limited oxidation‐state flexibility of the s‐block metals has long stood in the way of their participation in sophisticated π‐bonding arrangements, and truly antiaromatic systems containing s‐block metals are altogether absent or remain poorly defined. Using spectroscopic, structural, and computational techniques, we present herein the synthesis and authentication of a heterocyclic compound containing the alkaline earth metal beryllium that exhibits significant antiaromaticity, and detail its chemical reduction and Lewis‐base‐coordination chemistry.
KW  - antiaromaticity
KW  - aromaticity
KW  - beryllium
KW  - heterocycles
KW  - s-block metals
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-224447
VL  - 60
IS  - 7
SP  - 3812
EP  - 3819
ER  - 
TY  - JOUR
A1  - Hermann, Alexander
A1  - Fantuzzi, Felipe
A1  - Arrowsmith, Merle
A1  - Zorn, Theresa
A1  - Krummenacher, Ivo
A1  - Ritschel, Benedikt
A1  - Radacki, Krzysztof
A1  - Engels, Bernd
A1  - Braunschweig, Holger
T1  - Oxidation, Coordination, and Nickel-Mediated Deconstruction of a Highly Electron-Rich Diboron Analogue of 1,3,5-Hexatriene
JF  - Angewandte Chemie, International Edition
N2  - The reductive coupling of an N-heterocyclic carbene (NHC) stabilized (dibromo)vinylborane yields a 1,2-divinyl- diborene, which, although isoelectronic to a 1,3,5-triene, displays no extended p conjugation because of twisting of the C\(_2\)B\(_2\)C\(_2\) chain. While this divinyldiborene coordinates to copper(I) and platinum(0) in an η\(^2\)-B\(_2\) and η\(^4\)-C\(_2\)B\(_2\) fashion, respectively, it undergoes a complex rearrangement to an η\(^4\)-1,3-diborete upon complexation with nickel(0).
KW  - boron
KW  - diborenes
KW  - carbenes
KW  - conjugation
KW  - density-functional calculations
KW  - rearrangements
KW  - structure elucidation
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-240652
VL  - 59
IS  - 36
ER  - 
TY  - JOUR
A1  - Ramler, Jaqueline
A1  - Fantuzzi, Felipe
A1  - Geist, Felix
A1  - Hanft, Anna
A1  - Braunschweig, Holger
A1  - Engels, Bernd
A1  - Lichtenberg, Crispin
T1  - The dimethylbismuth cation: entry into dative Bi-Bi bonding and unconventional methyl exchange
JF  - Angewandte Chemie International Edition
N2  - The dimethyl bismuth cation, [BiMe\(_2\)(SbF\(_6\))], has been isolated and characterized. Reaction with BiMe\(_3\) allows access to the first compound featuring Bi→Bi donor–acceptor bonding. In solution, dynamic behavior with methyl exchange via an unusual S\(_E\)2 mechanism is observed, underlining the unique properties of bismuth species as soft Lewis acids with the ability to undergo reversible Bi−C bond cleavage.
KW  - inorganic chemistry
KW  - methyl exchange
KW  - bismuth
KW  - cationic species
KW  - electrophilic substitution
KW  - Lewis acidity
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256543
VL  - 60
ER  -