TY - JOUR A1 - Cui, Jingjing A1 - Dietz, Maximilian A1 - Härterich, Marcel A1 - Fantuzzi, Felipe A1 - Lu, Wei A1 - Dewhurst, Rian D. A1 - Braunschweig, Holger T1 - Diphosphino-Functionalized 1,8-Naphthyridines: a Multifaceted Ligand Platform for Boranes and Diboranes JF - Chemistry—A European Journal N2 - A 1,8-naphthyridine diphosphine (NDP) reacts with boron-containing Lewis acids to generate complexes featuring a number of different naphthyridine bonding modes. When exposed to diborane B\(_{2}\)Br\(_{4}\), NDP underwent self-deprotonation to afford [NDP-B\(_{2}\)Br\(_{3}\)]Br, an unsymmetrical diborane comprised of four fused rings. The reaction of two equivalents of monoborane BBr\(_{3}\) and NDP in a non-polar solvent provided the simple phosphine-borane adduct [NDP(BBr\(_{3}\))\(_{2}\)], which then underwent intramolecular halide abstraction to furnish the salt [NDP-BBr\(_{2}\)][BBr\(_{4}\)], featuring a different coordination mode from that of [NDP-B\(_{2}\)Br\(_{3}\)]Br. Direct deprotonation of NDP by KHMDS or PhCH2K generates mono- and dipotassium reagents, respectively. The monopotassium reagent reacts with one or half an equivalent of B\(_{2}\)(NMe\(_{2}\))\(_{2}\)Cl\(_{2}\) to afford NDP-based diboranes with three or four amino substituents. KW - pincer ligand KW - potassium reagent KW - diborane KW - naphthyridine KW - boron Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256994 VL - 27 IS - 63 ER - TY - JOUR A1 - Huang, Mingming A1 - Wu, Zhu A1 - Krebs, Johannes A1 - Friedrich, Alexandra A1 - Luo, Xiaoling A1 - Westcott, Stephen A. A1 - Radius, Udo A1 - Marder, Todd B. T1 - Ni-Catalyzed Borylation of Aryl Sulfoxides JF - Chemistry—A European Journal N2 - A nickel/N-heterocyclic carbene (NHC) catalytic system has been developed for the borylation of aryl sulfoxides with B\(_{2}\)(neop)\(_{2}\) (neop=neopentyl glycolato). A wide range of aryl sulfoxides with different electronic and steric properties were converted into the corresponding arylboronic esters in good yields. The regioselective borylation of unsymmetric diaryl sulfoxides was also feasible leading to borylation of the sterically less encumbered aryl substituent. Competition experiments demonstrated that an electron-deficient aryl moiety reacts preferentially. The origin of the selectivity in the Ni-catalyzed borylation of electronically biased unsymmetrical diaryl sulfoxide lies in the oxidative addition step of the catalytic cycle, as oxidative addition of methoxyphenyl 4-(trifluoromethyl)phenyl sulfoxide to the Ni(0) complex occurs selectively to give the structurally characterized complex trans-[Ni(ICy)\(_{2}\)(4-CF\(_{3}\)-C\(_{6}\)H\(_{4}\)){(SO)-4-MeO-C\(_{6}\)H\(_{4}\)}] 4. For complex 5, the isomer trans-[Ni(ICy)\(_{2}\)(C\(_{6}\)H\(_{5}\))(OSC\(_{6}\)H\(_{5}\))] 5-I was structurally characterized in which the phenyl sulfinyl ligand is bound via the oxygen atom to nickel. In solution, the complex trans-[Ni(ICy)\(_{2}\)(C\(_{6}\)H\(_{5}\))(OSC\(_{6}\)H\(_{5}\))] 5-I is in equilibrium with the S-bonded isomer trans-[Ni(ICy)\(_{2}\)(C\(_{6}\)H\(_{5}\))(SOC\(_{6}\)H\(_{5}\))] 5, as shown by NMR spectroscopy. DFT calculations reveal that these isomers are separated by a mere 0.3 kJ/mol (M06/def2-TZVP-level of theory) and connected via a transition state trans-[Ni(ICy)\(_{2}\)(C\(_{6}\)H\(_{5}\))(η\(^{2}\)-{SO}-C\(_{6}\)H\(_{5}\))], which lies only 10.8 kcal/mol above 5. KW - Boron KW - cross-coupling KW - N-heterocyclic carbenes KW - nickel KW - borylation Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256778 VL - 27 IS - 31 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 - Liu, Zhiqiang A1 - Kole, Goutam Kumar A1 - Budiman, Yudha P. A1 - Tian, Ya-Ming A1 - Friedrich, Alexandra A1 - Luo, Xiaoling A1 - Westcott, Stephen A. A1 - Radius, Udo A1 - Marder, Todd B. T1 - Transition metal catalyst-free, base-promoted 1,2-additions of polyfluorophenylboronates to aldehydes and ketones JF - Angewandte Chemie International Edition N2 - A novel protocol for the transition metal-free 1,2-addition of polyfluoroaryl boronate esters to aldehydes and ketones is reported, which provides secondary alcohols, tertiary alcohols, and ketones. Control experiments and DFT calculations indicate that both the ortho-F substituents on the polyfluorophenyl boronates and the counterion K\(^+\) in the carbonate base are critical. The distinguishing features of this procedure include the employment of commercially available starting materials and the broad scope of the reaction with a wide variety of carbonyl compounds giving moderate to excellent yields. Intriguing structural features involving O−H⋅⋅⋅O and O−H⋅⋅⋅N hydrogen bonding, as well as arene-perfluoroarene interactions, in this series of racemic polyfluoroaryl carbinols have also been addressed. KW - inorganic chemistry KW - transition metal-free KW - alcohol KW - 1,2-additionreaction KW - boronateesters KW - fluoroarene Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256487 VL - 60 IS - 30 ER - TY - JOUR A1 - Hagspiel, Stephan A1 - Fantuzzi, Felipe A1 - Dewhurst, Rian D. A1 - Gärtner, Annalena A1 - Lindl, Felix A1 - Lamprecht, Anna A1 - Braunschweig, Holger T1 - Adducts of the parent boraphosphaketene H\(_2\)BPCO and their decarbonylative insertion chemistry JF - Angewandte Chemie International Edition N2 - The first examples of Lewis base adducts of the parent boraphosphaketene (H\(_2\)B-PCO) and their cyclodimers are prepared. One of these adducts is shown to undergo mild decarbonylation and phosphinidene insertion into a B−C bond of a borole, forming very rare examples of 1,2-phosphaborinines, B/P isosteres of benzene. The strong donor properties of these 1,2-phosphaborinines are confirmed by the synthesis of their π complexes with the Group 6 metals. KW - inorganic chemistry KW - phosphorus KW - boron KW - decarbonylation KW - heterocycles KW - ketenes Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256470 VL - 60 IS - 24 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 - Chen, Xing A1 - Meng, Guoyun A1 - Liao, Guanming A1 - Rauch, Florian A1 - He, Jiang A1 - Friedrich, Alexandra A1 - Marder, Todd B. A1 - Wang, Nan A1 - Chen, Pangkuan A1 - Wang, Suning A1 - Yin, Xiaodong T1 - Highly Emissive 9-Borafluorene Derivatives: Synthesis, Photophysical Properties and Device Fabrication JF - Chemistry—A European Journal N2 - A series of 9-borafluorene derivatives, functionalised with electron-donating groups, have been prepared. Some of these 9-borafluorene compounds exhibit strong yellowish emission in solution and in the solid state with relatively high quantum yields (up to 73.6 % for FMesB-Cz as a neat film). The results suggest that the highly twisted donor groups suppress charge transfer, but the intrinsic photophysical properties of the 9-borafluorene systems remain. The new compounds showed enhanced stability towards the atmosphere, and exhibited excellent thermal stability, revealing their potential for application in materials science. Organic light-emitting diode (OLED) devices were fabricated with two of the highly emissive compounds, and they exhibited strong yellow-greenish electroluminescence, with a maximum luminance intensity of >22 000 cd m\(^{-2}\). These are the first two examples of 9-borafluorene derivatives being used as light-emitting materials in OLED devices, and they have enabled us to achieve a balance between maintaining their intrinsic properties while improving their stability. KW - boron heterocycles KW - photophysics KW - organic light-emitting diodes KW - luminescence KW - density functional calculations Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256738 VL - 27 IS - 20 ER - TY - JOUR A1 - Zottnick, Sven H. A1 - Sprenger, Jan A. P. A1 - Finze, Maik A1 - Müller‐Buschbaum, Klaus T1 - Statistic Replacement of Lanthanide Ions in Bis‐salicylatoborate Coordination Polymers for the Deliberate Control of the Luminescence Chromaticity JF - ChemistryOpen N2 - Based on the strand‐like coordination polymer (CP) type \(^{1}\)\(_{∞}\)[Ln(BSB)\(_{3}\)(py)\(_{2}\)], [BSB]−=bis‐salicylatoborate anion, mixed Eu/Tb‐containing compounds of the constitution \(^{1}\)\(_{∞}\)[Eu\(_{x}\)Tb\(_{1-x}\)(BSB)\(_{3}\)(py)\(_{2}\)] were synthesised ionothermally for a phase width of (x=0.25–0.75) and characterized regarding structure and optical properties. Previously, known only for other lanthanides, the mixed 1D−Eu/Tb‐CPs show excellent options for statistic replacement of the Ln‐cations during synthesis yielding solid solutions. The products are highly luminescent, with the chromaticity being a direct function of the amount of the respective Ln‐ions. Corresponding to an overall addition of emission intensities, the green Tb\(^{3+}\) emission and the red Eu\(^{3+}\) emission allow for a chromaticity control that also includes yellow emission. Control of the luminescence colour renders them suitable examples of the versatility of statistic replacement of metal ions in coordination chemistry. In addition, crystallization of [EMIm]\(_{2}\)[YCl\(_{5}\)(py)] illuminates possible other products of the ionothermal reactions of [EMIm][BSB] with LnCl\(_{3}\) constituted by components not being part of the main CPs. KW - borates KW - coordination polymers KW - ionic liquids KW - lanthanides KW - luminescence Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-239953 VL - 10 IS - 2 SP - 164 EP - 170 ER - TY - JOUR A1 - Budiman, Yudha P. A1 - Westcott, Stephen A. A1 - Radius, Udo A1 - Marder, Todd B. T1 - Fluorinated Aryl Boronates as Building Blocks in Organic Synthesis JF - Advanced Synthesis & Catalysis N2 - Organoboron compounds are well known building blocks for many organic reactions. However, under basic conditions, polyfluorinated aryl boronic acid derivatives suffer from instability issues that are accelerated in compounds containing an ortho‐fluorine group, which result in the formation of the corresponding protodeboronation products. Therefore, a considerable amount of research has focused on novel methodologies to synthesize these valuable compounds while avoiding the protodeboronation issue. This review summarizes the latest developments in the synthesis of fluorinated aryl boronic acid derivatives and their applications in cross‐coupling reactions and other transformations. image KW - homogeneous catalysis KW - boron reagents KW - boronates KW - fluorine KW - fluoroarene Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225908 VL - 363 IS - 9 SP - 2224 EP - 2255 ER - TY - JOUR A1 - Matler, Alexander A1 - Arrowsmith, Merle A1 - Schorr, Fabian A1 - Hermann, Alexander A1 - Hofmann, Alexander A1 - Lenczyk, Carsten A1 - Braunschweig, Holger T1 - Reactivity of Terminal Iron Borylenes and Bis(borylenes) with Carbodiimides: Cycloaddition, Metathesis, Insertion and C−H Activation Pathways JF - European Journal of Inorganic Chemistry N2 - The reactions of carbodiimides with the iron arylborylene complex [Fe=BDur(CO)\(_{3}\)(PMe\(_{3}\))] (Dur=2,3,5,6-Me\(_{4}\)C\(_{6}\)H) and the iron bis(borylene) complex [Fe{=BDur}{=BN(SiMe\(_{3}\))\(_{2}\)}(CO)\(_{3}\)] yield a wide variety of temperature-dependent products, including known FeBNC and novel FeBNB metallacycles, complexes of N-heterocyclic boracarbene and spiro-boracarbene ligands and a unique 1,3,2,4-diazadiborolyl pianostool complex, characterized by NMR spectroscopy and X-ray crystallography. The product distributions can be rationalized by considering sequences of cycloaddition, metathesis, insertion, and C−H activation pathways mainly governed by sterics. KW - structure elucidation KW - borylene complexes KW - cycloaddition KW - metathesis KW - reaction mechanisms Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-257397 VL - 2021 IS - 45 ER - TY - JOUR A1 - Philipp, Michael S. M. A1 - Krahfuss, Mirjam J. A1 - Radacki, Krzysztof A1 - Radius, Udo T1 - N‐Heterocyclic Carbene and Cyclic (Alkyl)(amino)carbene Adducts of Antimony(III) JF - European Journal of Inorganic Chemistry N2 - A systematic study on Lewis-acid/base adducts of N-heterocyclic carbenes (NHCs) and the cyclic (alkyl)(amino)carbene cAAC\(^{Me}\) (1-(2,6-di-iso-propylphenyl)-3,3,5,5-tetramethyl-pyrrolidin-2-ylidene) with antimony(III) chlorides of the general formula SbCl\(_{2}\)R (R=Cl, Ph, Mes) is presented. The reaction of the NHCs Me\(_{2}\)Im\(^{Me}\) (1,3,4,5-tetra-methyl-imidazolin-2-ylidene), iPr\(_{2}\)Im\(^{Me}\) (1,3-di-isopropyl-4,5-dimethyl-imidazolin-2-ylidene), Mes\(_{2}\)Im, Dipp\(_{2}\)Im (R\(_{2}\)Im=1,3-di-organyl-imidazolin-2-ylidene; Mes=2,4,6-trimethylphenyl, Dipp=2,6-di-isopropylphenyl) and cAAC\(^{Me}\) with antimony(III) compounds SbCl\(_{2}\)R (R=Cl (1), Ph (2) and Mes (3)) yields the adducts NHC ⋅ SbCl\(_{2}\)R (R=Cl (4), Ph (5) and Mes (6); NHC=Me\(_{2}\)Im\(^{Me}\) (a), iPr\(_{2}\)Im\(^{Me}\) (b), Dipp\(_{2}\)Im (c) and Mes\(_{2}\)Im (d)) and cAAC\(^{Me}\) ⋅ SbCl\(_{2}\)R (R=Cl (4 e) and Ph (5 e)). Thermal treatment of (Dipp\(_{2}\)Im) ⋅ SbCl\(_{2}\)Ar (Ar=Ph (5 c) and Mes (6 c)) in benzene leads to isomerization to the backbone coordinated \(^{a}\)NHC-adduct \(^{a}\)Dipp\(_{2}\)Im ⋅ SbCl\(_{2}\)Ar (Ar=Mes (7) and Ph (8)) (\(^{"a"}\) denotes “abnormal” coordination mode of the NHC) in high yields. One of the chloride substituents at antimony of 7 can be abstracted by GaCl3 or Ag[BF\(_{4}\)] to obtain the imidazolium salts [\(^{a}\)Dipp\(_{2}\)Im ⋅ SbClMes][BF\(_{4}\)] (9) and [\(^{a}\)Dipp\(_{2}\)Im ⋅ SbClMes][GaCl\(_{4}\)] (10). KW - N-Heterocyclic carbenes KW - antimony KW - cyclic (alkyl)(amino)carbenes KW - Lewis acid/base adducts KW - main group element halides Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-257408 VL - 2021 IS - 38 ER - TY - JOUR A1 - Full, Julian A1 - Panchal, Santosh P. A1 - Götz, Julian A1 - Krause, Ana‐Maria A1 - Nowak‐Król, Agnieszka T1 - Modular Synthesis of Organoboron Helically Chiral Compounds: Cutouts from Extended Helices JF - Angewandte Chemie International Edition N2 - Two types of helically chiral compounds bearing one and two boron atoms were synthesized by a modular approach. Formation of the helical scaffolds was executed by the introduction of boron to flexible biaryl and triaryl derived from small achiral building blocks. All‐ortho‐fused azabora[7]helicenes feature exceptional configurational stability, blue or green fluorescence with quantum yields (Φ\(_{fl}\)) of 18–24 % in solution, green or yellow solid‐state emission (Φ\(_{fl}\) up to 23 %), and strong chiroptical response with large dissymmetry factors of up to 1.12×10\(^{-2}\). Azabora[9]helicenes consisting of angularly and linearly fused rings are blue emitters exhibiting Φ\(_{fl}\) of up to 47 % in CH\(_{2}\)Cl\(_{2}\) and 25 % in the solid state. As revealed by the DFT calculations, their P–M interconversion pathway is more complex than that of H1. Single‐crystal X‐ray analysis shows clear differences in the packing arrangement of methyl and phenyl derivatives. These molecules are proposed as primary structures of extended helices. KW - chirality KW - circular dichroism KW - fluorescence KW - helicene KW - organoboron Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225775 VL - 60 IS - 8 SP - 4350 EP - 4357 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 - Kole, Goutam Kumar A1 - Merz, Julia A1 - Amar, Anissa A1 - Fontaine, Bruno A1 - Boucekkine, Abdou A1 - Nitsch, Jörn A1 - Lorenzen, Sabine A1 - Friedrich, Alexandra A1 - Krummenacher, Ivo A1 - Košćak, Marta A1 - Braunschweig, Holger A1 - Piantanida, Ivo A1 - Halet, Jean-François A1 - Müller-Buschbaum, Klaus A1 - Marder, Todd B. T1 - 2- and 2,7-substituted para-N-methylpyridinium pyrenes: syntheses, molecular and electronic structures, photophysical, electrochemical, and spectroelectrochemical properties and binding to double-stranded (ds) DNA JF - Chemistry - A European Journal N2 - Two N-methylpyridinium compounds and analogous N-protonated salts of 2- and 2,7-substituted 4-pyridyl-pyrene compounds were synthesised and their crystal structures, photophysical properties both in solution and in the solid state, electrochemical and spectroelectrochemical properties were studied. Upon methylation or protonation, the emission maxima are significantly bathochromically shifted compared to the neutral compounds, although the absorption maxima remain almost unchanged. As a result, the cationic compounds show very large apparent Stokes shifts of up to 7200 cm\(^{-1}\). The N-methylpyridinium compounds have a single reduction at ca. −1.5 V vs. Fc/Fc\(^+\) in MeCN. While the reduction process was reversible for the 2,7-disubstituted compound, it was irreversible for the mono-substituted one. Experimental findings are complemented by DFT and TD-DFT calculations. Furthermore, the N-methylpyridinium compounds show strong interactions with calf thymus (ct)-DNA, presumably by intercalation, which paves the way for further applications of these multi-functional compounds as potential DNA-bioactive agents. KW - inorganic chemistry KW - viologens KW - chromophores KW - luminescent KW - pyrenes KW - pyridinium Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256642 VL - 27 IS - 8 ER - TY - JOUR A1 - Brunecker, Carina A1 - Arrowsmith, Merle A1 - Fantuzzi, Felipe A1 - Braunschweig, Holger T1 - Platin‐vermittelte Kupplung von B=N‐Einheiten: Synthese von BNBN‐Analoga von 1,3‐Dienen und Butatrien JF - Angewandte Chemie N2 - Die 1:2-Reaktion von [μ-(dmpm)Pt(nbe)]\(_{2}\) (dmpm=Bis(dimethylphosphino)methan, nbe=Norbornen) mit Cl\(_{2}\)BNR(SiMe\(_{3}\)) (R=tBu, SiMe\(_{3}\)) führt durch eine B-N-Kupplung über eine ClSiMe\(_{3}\)-Eliminierung zu unsymmetrischen (N-Aminoboryl)aminoboryl-Pt\(^{I}\)\(_{2}\)-Komplexen. Eine anschließende intramolekulare ClSiMe\(_{3}\)-Eliminierung des tBu-Derivats führt zu einer Cyclisierung der BNBN-Einheit unter Bildung eines einzigartigen 1,3,2,4-Diazadiboretidin-2-yl-Liganden. Im Gegensatz hierzu steht die analoge Reaktion mit Br\(_{2}\)BN(SiMe\(_{3}\))\(_{2}\), die über eine zweifache BrSiMe\(_{3}\)-Eliminierung zu einem Pt\(^{II}\)\(_{2}\)-A-Frame-Komplex führt, der von einem linearen Isoster des Butatriens verbrückt wird. Strukturelle und theoretische Daten bestätigen eine π-Elektronen-Delokalisierung über die gesamte BNBN-Einheit. KW - 1,3,2,4-Diazadiboretidin-2-yl-Ligand KW - A-Frame-Komplex KW - B-N-Kupplung KW - Butatrien-Analogon KW - Isosterie Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-244792 VL - 133 IS - 31 SP - 17000 EP - 17004 ER - TY - JOUR A1 - Budiman, Yudha P. A1 - Lorenzen, Sabine A1 - Liu, Zhiqiang A1 - Radius, Udo A1 - Marder, Todd B. T1 - Base‐Free Pd‐Catalyzed C−Cl Borylation of Fluorinated Aryl Chlorides JF - Chemistry – A European Journal N2 - Catalytic C−X borylation of aryl halides containing two ortho‐fluorines has been found to be challenging, as most previous methods require stoichiometric amounts of base and the polyfluorinated aryl boronates suffer from protodeboronation, which is accelerated by ortho‐fluorine substituents. Herein, we report that a combination of Pd(dba)2 (dba=dibenzylideneacetone) with SPhos (2‐dicyclohexylphosphino‐2’,6’‐dimethoxybiphenyl) as a ligand is efficient to catalyze the C‐Cl borylation of aryl chlorides containing two ortho‐fluorine substituents. This method, conducted under base‐free conditions, is compatible with the resulting di‐ortho‐fluorinated aryl boronate products which are sensitive to base. KW - boronate ester KW - borylation KW - cross-coupling KW - fluoroarene KW - palladium-catalyzed Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225687 VL - 27 IS - 11 SP - 3869 EP - 3874 ER - TY - JOUR A1 - Krahfuss, Mirjam J. A1 - Radius, Udo T1 - N‐Heterocyclic Silylene Main Group Element Chemistry: Adduct Formation, Insertion into E−X Bonds and Cyclization of Organoazides JF - European Journal of Inorganic Chemistry N2 - Investigations concerning the reactivity of the N‐heterocyclic silylene Dipp\(_{2}\)NHSi (1, 1,3‐bis(2,6‐diisopropylphenyl)‐1,3‐diaza‐2‐silacyclopent‐4‐en‐2‐ylidene) towards selected alanes and boranes, elemental halides X\(_{2}\) (X=Br, I), selected halide containing substrates such as tin chlorides and halocarbons, as well as organoazides are presented. The NHSi adducts Dipp\(_{2}\)NHSi⋅AlI\(_{3}\) (2), Dipp\(_{2}\)NHSi⋅Al(C\(_{6}\)F\(_{5}\))\(_{3}\) (3), and Dipp\(_{2}\)NHSi⋅B(C\(_{6}\)F\(_{5}\))\(_{3}\) (4) were formed by the reaction of Dipp\(_{2}\)NHSi with the corresponding Lewis acids AlI\(_{3}\), Al(C\(_{6}\)F\(_{6}\))\(_{3}\) and B(C\(_{6}\)F\(_{5}\))\(_{3}\). Adducts 3 and 4 were tested with respect to their ability to activate small organic molecules, but no frustrated Lewis pair reactivity was observed. Reactions of Dipp\(_{2}\)NHSi with Br\(_{2}\), I\(_{2}\), Ph\(_{2}\)SnCl\(_{2}\) and Me\(_{3}\)SnCl led to formation of Dipp\(_{2}\)NHSiBr\(_{2}\) (5), Dipp\(_{2}\)NHSiI\(_{2}\) (6), Dipp\(_{2}\)NHSiCl\(_{2}\) (7) and {(Me\(_{3}\)Sn)N(Dipp)CH}\(_{2}\) (8), respectively. The reaction with the halocarbons methyl iodide, benzyl chloride, and benzyl bromide afforded the insertion products Dipp\(_{2}\)NHSi(I)(CH\(_{3}\)) (9), Dipp\(_{2}\)NHSi(Cl)(CH\(_{2}\)Ph) (10) and Dipp\(_{2}\)NHSi(Br)(CH\(_{2}\)Ph) (11). Reaction of Dipp\(_{2}\)NHSi with the organoazides Ad‐N\(_{3}\) (Ad=adamantyl) and TMS‐N\(_{3}\) (TMS=trimethylsilyl) led to the formation of 1‐Dipp\(_{2}\)NHSi‐2,5‐bis(adamantyl)‐tetrazoline (12) and bis(trimethylsilyl)amido azido silane (13), respectively. For 2,6‐(diphenyl)phenyl‐N\(_{3}\) C−H activation occurs and a cyclosilamine 14 was isolated. KW - arbenes KW - E−X bond activation KW - acid/base adducts KW - Organoazides KW - Silylenes Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-224507 VL - 2021 IS - 6 SP - 548 EP - 561 ER - TY - JOUR A1 - Oberdorf, Kai A1 - Hanft, Anna A1 - Ramler, Jacqueline A1 - Krummenacher, Ivo A1 - Bickelhaupt, Matthias A1 - Poater, Jordi A1 - Lichtenberg, Crispin T1 - Bismuth Amides Mediate Facile and Highly Selective Pn–Pn Radical‐Coupling Reactions (Pn=N, P, As) JF - Angewandte Chemie, International Edition N2 - The controlled release of well‐defined radical species under mild conditions for subsequent use in selective reactions is an important and challenging task in synthetic chemistry. We show here that simple bismuth amide species [Bi(NAr\(_2\))\(_3\)] readily release aminyl radicals [NAr\(_2\)]. at ambient temperature in solution. These reactions yield the corresponding hydrazines, Ar\(_2\)N−NAr\(_2\), as a result of highly selective N−N coupling. The exploitation of facile homolytic Bi−Pn bond cleavage for Pn−Pn bond formation was extended to higher homologues of the pnictogens (Pn=N–As): homoleptic bismuth amides mediate the highly selective dehydrocoupling of HPnR\(_2\) to give R\(_2\)Pn−PnR\(_2\). Analyses by NMR and EPR spectroscopy, single‐crystal X‐ray diffraction, and DFT calculations reveal low Bi−N homolytic bond‐dissociation energies, suggest radical coupling in the coordination sphere of bismuth, and reveal electronic and steric parameters as effective tools to control these reactions. KW - bismuth amides KW - radical species KW - pnictogen coupling KW - aminyl radicals KW - diphosphanes KW - heavier pnictogens KW - radical coupling Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-236582 VL - 60 IS - 12 ER - TY - JOUR A1 - Brückner, Tobias A1 - Heß, Merlin A1 - Stennett, Tom E. A1 - Rempel, Anna A1 - Braunschweig, Holger T1 - Synthesis of Boron Analogues of Enamines via Hydroamination of a Boron-Boron Triple Bond BT - Dedicated to Professor Wolfgang Kaim on the occasion of his 70th birthday JF - Angewandte Chemie, International Edition N2 - An N-heterocyclic-carbene-stabilized diboryne undergoes rapid, high-yielding and catalyst-free hydroamina- tion reactions with primary amines, yielding 1-amino-2-hydro- diborenes, which can be considered boron analogues of enamines. The electronics of the organic substituent at nitrogen influence the structure and further reactivity of the diborene product. With electron-rich anilines, a second hydroamination can occur at the diborene to generate 1,1-diamino-2,2-dihy- drodiboranes. With isopropylamine, the electronic influence of the alkyl substituent upon the diborene leads to an unprece- dented boron-mediated intramolecular N-dearylation reaction of an N-heterocyclic carbene unit. KW - boron KW - diborynes KW - diborenes KW - DFT KW - enamines KW - hydroamination KW - multiple bonds Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-240669 VL - 60 IS - 2 ER - TY - JOUR A1 - Zhang, Fangyuan A1 - Radacki, Krzysztof A1 - Braunschweig, Holger A1 - Lambert, Christoph A1 - Ravat, Prince T1 - Zinc-[7]helicenocyanine and its discrete π-stacked homochiral Dimer JF - Angewandte Chemie International Edition N2 - In this communication, we demonstrate a novel approach to prepare a discrete dimer of chiral phthalocyanine (Pc) by exploiting the flexible molecular geometry of helicenes, which enables structural interlocking and strong aggregation tendency of Pcs. Synthesized [7]helicene-Pc hybrid molecular structure, zinc-[7]helicenocyanine (Zn-7HPc), exclusively forms a stable dimeric pair consisting of two homochiral molecules. The dimerization constants were estimated to be as high as 8.96×10\(^6\) M\(^{−1}\) and 3.42×107 M\(^{−1}\) in THF and DMSO, respectively, indicating remarkable stability of dimer. In addition, Zn\(^{-7}\)HPc exhibited chiral self-sorting behavior, which resulted in preferential formation of a homochiral dimer also in the racemic sample. Two phthalocyanine subunits in the dimeric form strongly communicate with each other as revealed by a large comproportionation constant and observation of an IV-CT band for the thermodynamically stable mixed-valence state. KW - organic chemistry KW - supramolecular assembly KW - chirality KW - helicenes KW - homochiral dimer KW - phthalocyanines Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256534 VL - 60 ER -