TY - JOUR A1 - Belaidi, Houmam A1 - Rauch, Florian A1 - Zhang, Zuolun A1 - Latouche, Camille A1 - Boucekkine, Abdou A1 - Marder, Todd B. A1 - Halet, Jean-Francois T1 - Insights into the optical properties of triarylboranes with strongly electron-accepting bis(fluoromesityl)boryl groups: when theory meets experiment JF - ChemPhotoChem N2 - The photophysical properties (absorption, fluorescence and phosphorescence) of a series of triarylboranes of the form 4-D-C\(_6\)H\(_4\)-B(Ar)\(_2\) (D=\(^t\)Bu or NPh\(_2\); Ar=mesityl (Mes) or 2,4,6-tris(trifluoromethylphenyl (Fmes)) were analyzed theoretically using state-of-the-art DFT and TD-DFT methods. Simulated emission spectra and computed decay rate constants are in very good agreement with the experimental data. Unrestricted electronic computations including vibronic contributions explain the unusual optical behavior of 4-\(^t\)Bu-C\(_6\)H\(_4\)-B(Fmes)\(_2\) 2, which shows both fluorescence and phosphorescence at nearly identical energies (at 77 K in a frozen glass). Analysis of the main normal modes responsible for the phosphorescence vibrational fine structure indicates that the bulky tert-butyl group tethered to the phenyl ring is strongly involved. Interestingly, in THF solvent, the computed energies of the singlet and triplet excited states are very similar for compound 2 only, which may explain why 2 shows phosphorescence in contrast to the other members of the series. KW - boron KW - density functional calculations KW - luminescence KW - phosphorescence KW - photophysics KW - activated delayes flourescence KW - 3-coordinate organoboron compounds KW - light-emitting-diodes KW - phosphorescene spectra KW - molecular structures KW - high efficiency KW - pi-conjugation KW - trivalent boron KW - single photon KW - donor Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-205600 VL - 4 IS - 3 ER - TY - JOUR A1 - Liu, Xiaocui A1 - Ming, Wenbo A1 - Friedrich, Alexandra A1 - Kerner, Florian A1 - Marder, Todd B. T1 - Copper-Catalyzed Triboration of Terminal Alkynes Using B\(_2\)pin\(_2\): Efficient Synthesis of 1,1,2-Triborylalkenes JF - Angewandte Chemie International Edition N2 - We report herein the catalytic triboration of terminal alkynes with B\(_2\)pin\(_2\) (bis(pinacolato)diboron) using readily available Cu(OAc)\(_2\) and P\(^n\)Bu\(_3\). Various 1,1,2‐triborylalkenes, a class of compounds that have been demonstrated to be potential matrix metalloproteinase (MMP‐2) inhibitors, were obtained directly in moderate to good yields. The process features mild reaction conditions, a broad substrate scope, and good functional group tolerance. This copper‐catalyzed reaction can be conducted on a gram scale to produce the corresponding 1,1,2‐triborylalkenes in modest yields. The utility of these products was demonstrated by further transformations of the C−B bonds to prepare gem ‐dihaloborylalkenes (F, Cl, Br), monohaloborylalkenes (Cl, Br), and trans ‐diaryldiborylalkenes, which serve as important synthons and have previously been challenging to prepare. KW - boronate esters KW - borylation KW - cross-coupling KW - diboration KW - halogenation Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-206694 VL - 59 IS - 1 ER - TY - JOUR A1 - Bélanger-Chabot, Guillaume A1 - Braunschweig, Holger T1 - Hexahalogendiborat‐Dianionen: Eine neue Klasse binärer Borhalogenide JF - Angewandte Chemie N2 - Die elektronenpräzisen binären Borsubhalogenide [B\(_2\)X\(_6\)]\(^{2−}\) (X=F, Br, I) wurden synthetisiert und strukturell im Festkörper untersucht. Zudem konnte die vermutete Existenz von [B\(_2\)Cl\(_6\)]\(^{2−}\) mittels Röntgendiffraktometrie nachgewiesen werden. Diese Dianionen sind isoelektronisch zu den Hexahalogeniden des Ethans und können als Homologe des Tetrahalogenborat‐Anions BX\(_4\)\(^−\) betrachtet werden. Darüber hinaus gehören sie zu den seltenen Beispielen von elektronenpräzisen binären Borverbindungen (B\(_2\)X\(_4\), BX\(_3\), [BX\(_4\)]\(^−\)). KW - Binäre Verbindungen KW - Bor KW - Elektronenpräzise Diborate KW - Halogene Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-212605 VL - 131 IS - 40 ER - TY - JOUR A1 - Tendera, Lukas A1 - Schaub, Thomas A1 - Krahfuss, Mirjam J. A1 - Kuntze‐Fechner, Maximilian W. A1 - Radius, Udo T1 - Large vs. Small NHC Ligands in Nickel(0) Complexes: The Coordination of Olefins, Ketones and Aldehydes at [Ni(NHC)\(_{2}\)] JF - European Journal of Inorganic Chemistry N2 - Investigations concerning the reactivity of Ni(0) complexes [Ni(NHC)\(_{2}\)] of NHCs (N‐heterocyclic carbene) of different steric demand, Mes\(_{2}\)Im (= 1,3‐dimesitylimidazoline‐2‐ylidene) and iPr\(_{2}\)Im (= 1,3‐diisopropyl‐imidazoline‐2‐ylidene), with olefins, ketones and aldehydes are reported. The reaction of [Ni(Mes\(_{2}\)Im)\(_{2}\)] 1 with ethylene or methyl acrylate afforded the complexes [Ni(Mes\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐C\(_{2}\)H\(_{4}\))] 3 and [Ni(Mes\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐(C,C)‐H\(_{2}\)C=CHCOOMe)] 4, as it was previously reported for [Ni\(_{2}\)(iPr\(_{2}\)Im)\(_{4}\)(µ‐(η\(^{2}\):η\(^{2}\))‐COD)] 2 as a source for [Ni(iPr\(_{2}\)Im)\(_{2}\)]. In contrast to 2, complex 1 does not react with sterically more demanding olefins such as tetramethylethylene, 1,1‐diphenylethylene and cyclohexene. The reaction of [Ni(NHC)\(_{2}\)] with more π‐acidic ketones or aldehydes led to formation of complexes with side‐on η\(^{2}\)‐(C,O)‐coordinating ligands: [Ni(iPr\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=CH\(^{t}\)Bu)] 5, [Ni(iPr\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=CHPh)] 6, [Ni(iPr\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=CMePh)] 7, [Ni(iPr\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=CPh\(_{2}\))] 8, [Ni(iPr\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=C(4‐F‐C\(_{6}\)H\(_{4}\))\(_{2}\))] 9, [Ni(iPr\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=C(OMe)(CF\(_{3}\)))] 10 and [Ni(Mes\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=CHPh)] 11, [Ni(Mes\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=CH(CH(CH\(_{3}\))\(_{2}\)))] 12, [Ni(Mes\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=CH(4‐NMe\(_{2}\)‐C\(_{6}\)H\(_{4}\)))] 13, [Ni(Mes\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=CH(4‐OMe‐C\(_{6}\)H\(_{4}\)))] 14, [Ni(Mes\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=CPh\(_{2}\))] 15 and [Ni(Mes\(_{2}\)Im)\(_{2}\)(η\(^{2}\)‐O=C(4‐F‐C\(_{6}\)H\(_{4}\))\(_{2}\))] 16. The reaction of 1 and 2 with these simple aldehydes and ketones does not lead to a significantly different outcome, but NHC ligand rotation is hindered for the Mes\(_{2}\)Im complexes 3, 4 and 11–16 according to NMR spectroscopy. The solid‐state structures of 3, 4, 11 and 12 reveal significantly larger C\(_{NHC}\)‐Ni‐C\(_{NHC}\) angles in the Mes\(_{2}\)Im complexes compared to the iPr\(_{2}\)Im complexes. As electron transfer in d\(^{8}\)‐ (or d\(^{10}\)‐) ML\(_{2}\) complexes to π‐acidic ligands depends on the L–M–L bite angle, the different NHCs lead thus to a different degree of electron transfer and activation of the olefin, aldehyde or ketone ligand, i.e., [Ni(iPr\(_{2}\)Im)\(_{2}\)] is the better donor to these π‐acidic ligands. Furthermore, we identified two different side products from the reaction of 1 with benzaldehyde, trans‐[Ni(Mes\(_{2}\)Im)\(_{2}\)H(OOCPh)] 17 and [Ni\(_{2}\)(Mes\(_{2}\)Im)\(_{2}\)(µ\(_{2}\)‐CO)(µ\(_{2}\)‐η\(^{2}\)‐C,O‐PhCOCOPh)] 18, which indicate that radical intermediates and electron transfer processes might be of importance in the reaction of 1 with aldehydes and ketones. KW - Nickel Complexes KW - N‐Heterocyclic Carbenes KW - NHC Complexes KW - Olefin Complexes KW - Aldehyde Complexes Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-216058 VL - 2020 IS - 33 SP - 3194 EP - 3207 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 - Hock, Andreas A1 - Werner, Luis A1 - Riethmann, Melanie A1 - Radius, Udo T1 - Bis‐NHC Aluminium and Gallium Dihydride Cations [(NHC)\(_{2}\)EH\(_{2}\)]\(^{+}\) (E = Al, Ga) JF - European Journal of Inorganic Chemistry N2 - The NHC alane and gallane adducts (NHC)·AlH\(_{2}\)I (NHC = Me\(_{2}\)Im\(^{Me}\) 7, iPr\(_{2}\)Im 8, iPr\(_{2}\)Im\(^{Me}\) 9) and (NHC)·GaH\(_{2}\)I (NHC = Me\(_{2}\)Im\(^{Me}\) 10, iPr\(_{2}\)Im\(^{Me}\) 11, Dipp\(_{2}\)Im 12; R\(_{2}\)Im = 1,3‐di‐organyl‐imidazolin‐2‐ylidene; Dipp = 2,6‐diisopropylphenyl; iPr = isopropyl; Me\(_{2}\)Im\(^{Me}\) = 1,3,4,5‐tetra‐methyl‐imidazolin‐2‐ylidene) were prepared either by the simple yet efficient reaction of the NHC adduct (NHC)·AlH\(_{3}\) with elemental iodine or by the treatment of (NHC)·GaH\(_{3}\) with an excess of methyl iodide at room temperature. The reaction of one equivalent of the group 13 NHC complexes with an additional equivalent of the corresponding NHC afforded cationic aluminium and gallium hydrides [(NHC)\(_{2}\)·AlH\(_{2}\)]\(^{+}\)I− (NHC = Me\(_{2}\)Im\(^{Me}\) 13, iPr\(_{2}\)Im 14, iPr\(_{2}\)Im\(^{Me}\) 15) and [(NHC)\(_{2}\)·GaH\(_{2}\)]\(^{+}\)I− (NHC = Me\(_{2}\)Im\(^{Me}\) 16, iPr\(_{2}\)Im\(^{Me}\) 17) and the normal and abnormal NHC coordinated compound [(Dipp\(_{2}\)Im)·GaH\(_{2}\)(aDipp\(_{2}\)Im)]+I− 18. Compounds 7–18 were isolated and characterized by means of elemental analysis, IR and multinuclear NMR spectroscopy and by X‐ray diffraction of the compounds 7, 9, 10, 15, 16 and 18. KW - aluminium KW - cations KW - Gallium KW - main group elements KW - heterocyclic carbenes Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-217928 VL - 2020 IS - 42 SP - 4015 EP - 4023 ER - TY - JOUR A1 - Mansour, Ahmed M. A1 - Steiger, Christoph A1 - Nagel, Christoph A1 - Schatzschneider, Ulrich T1 - Wavelength‐dependent control of the CO release kinetics of manganese(I) tricarbonyl PhotoCORMs with benzimidazole coligands JF - European Journal of Inorganic Chemistry N2 - A series of photoactivatable CO‐releasing molecules (PhotoCORMs) was prepared from manganese pentacarbonyl bromide and 1H‐benzimidazol‐2‐ylmethyl‐(N‐phenyl)amine ligands (L) bearing different electron‐donating and electron‐withdrawing groups R = H, 4‐CH\(_3\), 4‐OCH\(_3\), 4‐Cl, 4‐NO\(_2\), 2‐, 3‐, and 4‐COOCH\(_3\) on the phenyl substituent to give octahedral manganese(I) complexes of the general formula [MnBr(CO)\(_3\)(L)]. Aerated DMSO solutions of the compounds are stable in the dark for 16 h with no CO release. However, the compounds rapidly release CO upon illumination at 412–525 nm, depending on the substitution pattern. Its influence on the photophysical and photochemical properties was systematically explored using UV/Vis spectroscopy and CO release measurements with a commercial gas sensor system. In the nitro‐substituted compound, the electronically excited state switched from benzimidazole‐ to phenyl‐centered, leading to a markedly different photochemical behavior of this visible‐light activated PhotoCORM. KW - CO‐releasing molecules (CORMs) KW - Manganese Carbonyl ligands KW - Benzimidazole KW - TDDFT Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-218362 VL - 2019 IS - 42 ER - TY - JOUR A1 - Liu, Xiaocui A1 - Ming, Wenbo A1 - Friedrich, Alexandra A1 - Marder, Todd B. T1 - Kupfer‐katalysierte Triborierung terminaler Alkine mit B2pin2: Effiziente Synthese von 1,1,2‐Triborylalkenen JF - Angewandte Chemie N2 - Wir berichten über die katalytische Triborierung terminaler Alkine mit B\(_2\)pin\(_2\) (Bis‐(pinakolato)‐dibor) unter Verwendung von einfach zugänglichem Cu(OAc)\(_2\) und P\(^n\)Bu\(_3\). Verschiedene 1,1,2‐Triborylalkene, eine Verbindungsklasse mit potentieller Funktion als Matrix‐Metallo‐Proteinase(MMP‐2)‐Inhibitor, werden direkt in mäßigen bis guten Ausbeuten erhalten. Das Verfahren zeichnet sich durch milde Reaktionsbedingungen, ein breites Substratspektrum und eine gute Verträglichkeit gegenüber funktionellen Gruppen aus. Diese Cu‐katalysierte Reaktion kann im Gramm‐Maßstab durchgeführt werden und liefert die entsprechenden 1,1,2‐Triborylalkene in mäßigen Ausbeuten. Die Verwendung solcher Verbindungen wird anhand weiterer Transformationen der C−B‐Bindungen zur Darstellung eines geminalen Dihalogenborylalkens (F, Cl, Br), eines Monohalogendiborylalkens (Cl, Br) und eines trans‐Diaryldiborylalkens demonstriert, welche bedeutende Synthesebausteine darstellen und bisher nur schwer zugänglich waren. KW - Boronatester KW - Borylierung KW - Diborierung KW - Halogenierung KW - Kreuzkupplungen Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-219699 VL - 132 IS - 1 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 - Schmidt, Uwe A1 - Werner, Luis A1 - Arrowsmith, Merle A1 - Deissenberger, Andrea A1 - Hermann, Alexander A1 - Hofmann, Alexander A1 - Ullrich, Stefan A1 - Mattock, James D. A1 - Vargas, Alfredo A1 - Braunschweig, Holger T1 - Trans‐selektive Dihydroborierung eines cis‐Diborens durch Insertion: Synthese eines linearen sp\(^3\)‐sp\(^2\)‐sp\(^3\)‐Triborans und anschließende Kationisierung JF - Angewandte Chemie N2 - Die Reaktion zwischen Aryl‐ und Amino(dihydro)boranen und Dibora[2]ferrocenophan 1 führt zur Bildung von 1,3‐trans‐Dihydrotriboranen durch formale Hydrierung und Insertion eines Borylens in die B=B Doppelbindung. Die Aryltriboran‐Derivate unterliegen einer reversiblen Photoisomerisierung zugunsten eines cis‐1,2‐μ‐H‐3‐Hydrotriborans, während eine Hydridabstraktion zu kationischen Triboranen führt, welche die ersten doppelt basenstabilisierten B\(_3\)H\(_4\)\(^+\)‐Analoga darstellen. KW - Diboren KW - Hydroborierung KW - Kation KW - Photoisomerisierung KW - Triboran Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-219713 VL - 132 IS - 1 ER - TY - JOUR A1 - Bélanger‐Chabot, Guillaume A1 - Braunschweig, Holger T1 - Hexahalodiborate Dianions: A New Family of Binary Boron Halides JF - Angewandte Chemie International Edition N2 - The electron‐precise binary boron subhalide species [B\(_2\)X\(_6\)]\(^{2−}\) X=F, Br, I) were synthesized and their structures confirmed by X‐ray crystallography. The existence of the previously claimed [B\(_2\)Cl\(_6\)]\(^{2−}\), which had been questioned, was also confirmed by X‐ray crystallography. The dianions are isoelectronic to hexahaloethanes, are subhalide analogues of the well‐known tetrahaloborate anions (BX\(_4\)\(^−\)), and are rare examples of molecular electron‐precise binary boron species beyond B\(_2\)X\(_4\), BX\(_3\), and [BX\(_4\)]\(^−\). KW - binary species KW - boron KW - electron-precise diborates KW - halogens Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-219688 VL - 58 IS - 40 ER - TY - JOUR A1 - Schmidt, Uwe A1 - Werner, Luis A1 - Arrowsmith, Merle A1 - Deissenberger, Andrea A1 - Hermann, Alexander A1 - Hofmann, Alexander A1 - Ullrich, Stefan A1 - Mattock, James D. A1 - Vargas, Alfredo A1 - Braunschweig, Holger T1 - trans-Selective Insertional Dihydroboration of a cis-Diborene: Synthesis of Linear sp\(^3\)-sp\(^2\)-sp\(^3\)-Triboranes and Subsequent Cationization JF - Angewandte Chemie International Edition N2 - The reaction of aryl‐ and amino(dihydro)boranes with dibora[2]ferrocenophane 1 leads to the formation 1,3‐trans ‐dihydrotriboranes by formal hydrogenation and insertion of a borylene unit into the B=B bond. The aryltriborane derivatives undergo reversible photoisomerization to the cis ‐1,2‐μ‐H‐3‐hydrotriboranes, while hydride abstraction affords cationic triboranes, which represent the first doubly base‐stabilized B3H4\(^+\) analogues. KW - cations KW - hydroboration KW - photoisomerization KW - triboranes KW - diborenes Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-208090 VL - 59 IS - 1 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 - 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 - 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 - Wirthensohn, Raphael A1 - Finze, Maik T1 - The crystal structure of trimethylsulfonium tris(trifluoromethylsulfonyl)methanide, C\(_7\)H\(_9\)F\(_9\)O\(_6\)S\(_4\) JF - Zeitschrift für Kristallographie - New Crystal Structures N2 - C\(_7\)H\(_9\)F\(_9\)O\(_6\)S\(_4\), orthorhombic, P2\(_1\)2\(_1\)2\(_1\) (no. 19), a = 8.80180(10) Å, b= 10.96580(10) Å, c = 16.91360(10) Å,V= 1632.48(3) Å\(^3\), Z= 4, R\(_{gt}\)(F) = 0.0222, wR\(_{ref}\)(F\(^2\)) = 0.0604, T = 100 K. KW - chemistry Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-231358 VL - 236 IS - 2 ER - TY - JOUR A1 - Emmert, Marcel A1 - Heß, Konrad A1 - Gräb, Patrick A1 - Geidel, Ekkehard T1 - Experiments to Introduce Students into the Temperature Dependence of the Reaction Rate JF - World Journal of Chemical Education N2 - It is a challenge in chemical education to understand basic principles of chemical reaction kinetics on an experimental basis because of the relatively extensive experimental setup and the often time-consuming measurement series. This contribution offers an introduction into the field of the temperature dependence of reaction rate with easy-to-use experiments. Data logging systems have been used to get sufficient data-sets to evaluate different measurements in reaction kinetics. Several experiments were designed for practical courses in chemistry, which allow students to derive the simple van‘t Hoff rule on the one hand. On the other hand, the Arrhenius equation can only be derived on the basis of experimental data with the help of information from collision theory and Maxwell-Boltzmann distribution. KW - temperature dependence of reaction rate KW - van‘t Hoff rule KW - Arrhenius equation KW - ow-cost photometer Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-229993 VL - 8 IS - 2 ER - TY - JOUR A1 - Ferger, Matthias A1 - Berger, Sarina M. A1 - Rauch, Florian A1 - Schönitz, Markus A1 - Rühe, Jessica A1 - Krebs, Johannes A1 - Friedrich, Alexandra A1 - Marder, Todd B. T1 - Synthesis of Highly Functionalizable Symmetrically and Unsymmetrically Substituted Triarylboranes from Bench-Stable Boron Precursors JF - Chemistry—A European Journal N2 - A novel and convenient methodology for the one-pot synthesis of sterically congested triarylboranes by using bench-stable aryltrifluoroborates as the boron source is reported. This procedure gives systematic access to symmetrically and unsymmetrically substituted triarylboranes of the types BAr\(_{2}\)Ar’ and BArAr'Ar’’, respectively. Three unsymmetrically substituted triarylboranes as well as their iridium-catalyzed C−H borylation products are reported. These borylated triarylboranes contain one to three positions that can subsequently be orthogonally functionalized in follow-up reactions, such as Suzuki-Miyaura cross-couplings or Sonogashira couplings. KW - synthetic methods KW - boranes KW - borylation KW - chromophore KW - functionalization Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256827 VL - 27 IS - 35 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 - TY - JOUR A1 - Schorr, Fabian A1 - Schopper, Nils A1 - Riensch, Nicolas A1 - Fantuzzi, Felipe A1 - Neder, Marco A1 - Dewhurst, Rian D. A1 - Thiess, Thorsten A1 - Brückner, Tobias A1 - Hammond, Kai A1 - Helten, Holger A1 - Finze, Maik A1 - Braunschweig, Holger T1 - Controlled Synthesis of Oligomers Containing Main-Chain B(sp\(^{2}\))-B(sp\(^{2}\)) Bonds JF - Chemistry—A European Journal N2 - A number of novel alkynyl-functionalized diarylbis(dimethylamino)diboranes(4) are prepared by salt metathesis, and the appended alkynyl groups are subjected to hydroboration. Their reactions with monohydroboranes lead to discrete boryl-appended diborane(4) species, while dihydroboranes induce their catenation to oligomeric species, the first known examples of well-characterized macromolecular species with B−B bonds. The oligomeric species were found to comprise up to ten repeat units and are soluble in common organic solvents. Some of the oligomeric species have good air stability and all were characterized by NMR and vibrational spectroscopy and size-exclusion chromatography techniques. KW - oligomerization KW - boron KW - catenation KW - diborane KW - hydroboration Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-257274 VL - 27 IS - 64 ER -