@unpublished{BraunschweigKrummenacherLichtenbergetal.2016, author = {Braunschweig, Holger and Krummenacher, Ivo and Lichtenberg, Crispin and Mattock, James and Sch{\"a}fer, Marius and Schmidt, Uwe and Schneider, Christoph and Steffenhagen, Thomas and Ullrich, Stefan and Vargas, Alfredo}, title = {Dibora[2]ferrocenophane: A Carbene-Stabilized Diborene in a Strained cis-Configuration}, series = {Angewandte Chemie, International Edition}, journal = {Angewandte Chemie, International Edition}, doi = {10.1002/anie.201609601}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-141981}, pages = {9}, year = {2016}, abstract = {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.}, subject = {Metallocene}, language = {en} } @article{BraunschweigKramer2014, author = {Braunschweig, Holger and Kramer, T.}, title = {Crystal structure of μ-1κC:2(\(η^2\))-carbonyl-carbonyl-1κC-chlorido-2κCl-μ-chloridoborylene-1:2\(κ^2\) B:B-[1(\(η^5\))-pentamethylcyclopentadienyl](tricyclohexylphosphane-2κP)iron(II)platinum(II) benzene monosolvate}, volume = {70}, number = {11}, doi = {10.1107/S1600536814023381}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-120120}, pages = {421-423}, year = {2014}, abstract = {In the mol­ecular structure of the dinuclear title compound \([η^5-(C_5(CH_3)_5)(CO)Fe{(μ-BCl)(μ-CO)}PtCl(P(C_6H_{11})_3)]·C_6H_6\), the two metal atoms, iron(II) and platinum(II), are bridged by one carbonyl (μ-CO) and one chlorido­borylene ligand (μ-BCl). The \(Pt^{II}\) atom is additionally bound to a chloride ligand situated trans to the bridging borylene, and a tri­cyclo­hexyl­phosphane ligand \((PCy_3)\) trans to the carbonyl ligand, forming a distorted square-planar structural motif at the \(Pt^{II}\) atom. The \(Fe_{II}\) atom is bound to a penta­methyl­cyclo­penta­dienyl ligand \([η^5-C_5(CH_3)_5]\) and one carbonyl ligand (CO), forming a piano-stool structure. Additionally, one benzene solvent mol­ecule is incorporated into the crystal structure, positioned staggered relative to the penta­methyl­cyclo­penta­dienyl ligand at the \(Fe^{II}\) atom, with a centroid-centroid separation of 3.630 (2) {\AA}.}, language = {en} } @article{BraunschweigEwingGhoshetal.2016, author = {Braunschweig, Holger and Ewing, William C. and Ghosh, Sundargopal and Kramer, Thomas and Mattock, James D. and {\"O}streicher, Sebastian and Vargas, Alfredo and Werner, Christine}, title = {Trimetallaborides as starting points for the syntheses of large metal-rich molecular borides and clusters}, series = {Chemical Science}, volume = {7}, journal = {Chemical Science}, number = {1}, doi = {10.1039/c5sc03206g}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-191511}, pages = {109-116}, year = {2016}, abstract = {Treatment of an anionic dimanganaborylene complex ([{Cp(CO)\(_2\)Mn}\(_2\)B]\(^-\)) with coinage metal cations stabilized by a very weakly coordinating Lewis base (SMe\(_2\)) led to the coordination of the incoming metal and subsequent displacement of dimethylsulfide in the formation of hexametalladiborides featuring planar four-membered M\(_2\)B\(_2\) cores (M = Cu, Au) comparable to transition metal clusters constructed around four-membered rings composed solely of coinage metals. The analogies between compounds consisting of B\(_2\)M\(_2\) units and M\(_4\) (M = Cu, Au) units speak to the often overlooked metalloid nature of boron. Treatment of one of these compounds (M = Cu) with a Lewis-basic metal fragment (Pt(PCy\(_3\))\(_2\)) led to the formation of a tetrametallaboride featuring two manganese, one copper and one platinum atom, all bound to boron in a geometry not yet seen for this kind of compound. Computational examination suggests that this geometry is the result of d\(^{10}\)-d\(^{10}\) dispersion interactions between the copper and platinum fragments.}, language = {en} } @article{BraunschweigDewhurstSchwabetal.2010, author = {Braunschweig, Holger and Dewhurst, Rian D. and Schwab, Katrin and Wagner, Katharina}, title = {{N ',N ''-Bis[2,6-bis(1-methylethyl)phenyl]-N,N-dimethylguanidinato-kappa N-2 ',N ''}dibromidoborane}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67622}, year = {2010}, abstract = {In the molecular structure of the title compound, C27H40N3BBr2, the B atom is connected to two bromide substituents and a guanidinate scaffold, forming a four- membered ring. An aryl group is connected to each N atom in the ring that contains two isopropyl groups in positions 2 and 6.}, subject = {Anorganische Chemie}, language = {en} } @article{BraunschweigDamme2010, author = {Braunschweig, Holger and Damme, Alexander}, title = {1,2-Bis(dimethylamino)-1,2-bis(2,4,6-triisopropylphenyl)diborane(4)}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67639}, year = {2010}, abstract = {In the molecular structure of the title compound, C34H58B2N2, each B atom of the diborane(4) is connected to one dimethylamino group and one Tip ligand (Tip = 2,4,6-triisopropylphenyl). These findings indicate that the increased steric demand of the Tip groups exerts influence solely on the B—B separation but not on the overall geometry of the title compound.}, subject = {Anorganische Chemie}, language = {en} } @article{BraunschweigConstantinidisDellermannetal.2016, author = {Braunschweig, Holger and Constantinidis, Philipp and Dellermann, Theresa and Ewing, William and Fischer, Ingo and Hess, Merlin and Knight, Fergus and Rempel, Anna and Schneider, Christoph and Ullrich, Stefan and Vargas, Alfredo and Woolins, Derek}, title = {Highly Strained Heterocycles Constructed from Boron-Boron Multiple Bonds and Heavy Chalcogens}, series = {Angewandte Chemie, International Edition}, volume = {55}, journal = {Angewandte Chemie, International Edition}, number = {18}, doi = {10.1002/anie.201601691}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-138237}, pages = {5606 -- 5609}, year = {2016}, abstract = {The reactions of a diborene with elemental selenium or tellurium are shown to afford a diboraselenirane or diboratellurirane, respectively. These reactions are reminiscent of the sequestration of subvalent oxygen and nitrogen in the formation of oxiranes and aziridines; however, such reactivity is not known between alkenes and the heavy chalcogens. Although carbon is too electronegative to affect the reduction of elements with lower relative electronegativity, the highly reducing nature of the B B double bond enables reactions with Se0 and Te0. The capacity of multiple bonds between boron atoms to donate electron density is highlighted in reactions where diborynes behave as nucleophiles, attacking one of the two Te atoms of diaryltellurides, forming salts consisting of diboratellurenium cations and aryltelluride anions.}, subject = {Bor}, language = {en} } @unpublished{BraunschweigBruecknerDeissenbergeretal.2017, author = {Braunschweig, Holger and Br{\"u}ckner, Tobias and Deißenberger, Andrea and Dewhurst, Rian and Gackstatter, Annika and G{\"a}rtner, Annalena and Hofmann, Alexander and Kupfer, Thomas and Prieschl, Dominic and Thiess, Torsten and Wang, Sunewang Rixin}, title = {Reaction of Dihalodiboranes(4) with N-Heterocyclic Silylenes: Facile Construction of 1-Aryl-2-Silyl-1,2-Diboraindanes}, series = {Chemistry, A European Journal}, journal = {Chemistry, A European Journal}, doi = {10.1002/chem.201702377}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-153068}, year = {2017}, abstract = {Dihalodiboranes(4) react with an N-heterocyclic silylene (NHSi) to generate NHSi-adducts of 1-aryl-2-silyl-1,2-diboraindanes as confirmed by X-ray crystallography, featuring the functionalization of both B-X (X = halogen) bonds and a C-H bond under mild conditions. Coordination of a third NHSi to the proposed 1,1-diaryl- 2,2-disilyldiborane(4) intermediates, generated by a two-fold B-X insertion, may be crucial for the C-H borylation that leads to the final products. Notably, our results demonstrate the first C-H borylation with a strong B-F bond activated by silylene insertion.}, language = {en} } @article{BraunschweigArnoldGruss2011, author = {Braunschweig, Holger and Arnold, Thomas and Gruss, Katrin}, title = {cyclo-Tri-mu-oxido-tris{[(eta 5,eta 5)-1,2-bis(cyclopentadienyl)-1,1,2,2-tetramethyldisilane]zirconium(IV)}: atrimeric disila-bridged oxidozirconocene}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-74737}, year = {2011}, abstract = {no abstract available}, subject = {Chemie}, language = {en} } @article{BergerRueheSchwarzmannetal.2021, author = {Berger, Sarina M. and R{\"u}he, Jessica and Schwarzmann, Johannes and Phillipps, Alexandra and Richard, Ann-Katrin and Ferger, Matthias and Krummenacher, Ivo and Tumir, Lidija-Marija and Ban, Željka and Crnolatac, Ivo and Majhen, Dragomira and Barišić, Ivan and Piantanida, Ivo and Schleier, Domenik and Griesbeck, Stefanie and Friedrich, Alexandra and Braunschweig, Holger and Marder, Todd B.}, title = {Bithiophene-Cored, mono-, bis-, and tris-(Trimethylammonium)-Substituted, bis-Triarylborane Chromophores: Effect of the Number and Position of Charges on Cell Imaging and DNA/RNA Sensing}, series = {Chemistry—A European Journal}, volume = {27}, journal = {Chemistry—A European Journal}, number = {56}, doi = {10.1002/chem.202102308}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256963}, pages = {14057-14072}, year = {2021}, abstract = {The synthesis, photophysical, and electrochemical properties of selectively mono-, bis- and tris-dimethylamino- and trimethylammonium-substituted bis-triarylborane bithiophene chromophores are presented along with the water solubility and singlet oxygen sensitizing efficiency of the cationic compounds Cat\(^{1+}\), Cat\(^{2+}\), Cat(i)\(^{2+}\), and Cat\(^{3+}\). Comparison with the mono-triarylboranes reveals the large influence of the bridging unit on the properties of the bis-triarylboranes, especially those of the cationic compounds. Based on these preliminary investigations, the interactions of Cat\(^{1+}\), Cat\(^{2+}\), Cat(i)\(^{2+}\), and Cat\(^{3+}\) with DNA, RNA, and DNApore were investigated in buffered solutions. The same compounds were investigated for their ability to enter and localize within organelles of human lung carcinoma (A549) and normal lung (WI38) cells showing that not only the number of charges but also their distribution over the chromophore influences interactions and staining properties.}, language = {en} } @article{BachmannHelbigCrumbachetal.2022, author = {Bachmann, Jonas and Helbig, Andreas and Crumbach, Merian and Krummenacher, Ivo and Braunschweig, Holger and Helten, Holger}, title = {Fusion of Aza- and Oxadiborepins with Furans in a Reversible Ring-Opening Process Furnishes Versatile Building Blocks for Extended π-Conjugated Materials}, series = {Chemistry - A European Journal}, volume = {28}, journal = {Chemistry - A European Journal}, number = {63}, doi = {10.1002/chem.202202455}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-293926}, year = {2022}, abstract = {A modular synthesis of both difurooxa- and difuroazadiborepins from a common precursor is demonstrated. Starting from 2,2′-bifuran, after protection of the positions 5 and 5' with bulky silyl groups, formation of the novel polycycles proceeds through opening of the furan rings to a dialkyne and subsequent re-cyclization in the borylation step. The resulting bifuran-fused diborepins show pronounced stability, highly planar tricyclic structures, and intense blue light emission. Deprotection and transformation into dibrominated building blocks that can be incorporated into π-extended materials can be performed in one step. Detailed DFT calculations provide information about the aromaticity of the constituent rings of this polycycle.}, language = {en} } @unpublished{AuerhammerArrowsmithBoehnkeetal.2018, author = {Auerhammer, Dominic and Arrowsmith, Merle and B{\"o}hnke, Julian and Braunschweig, Holger and Dewhurst, Rian D. and Kupfer, Thomas}, title = {Brothers from Another Mother: a Borylene and its Dimer are Non-Interconvertible but Connected through Reactivity}, series = {Chemical Science}, journal = {Chemical Science}, doi = {10.1039/C7SC04789D}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-157125}, year = {2018}, abstract = {The self-stabilizing, tetrameric cyanoborylene [(cAAC)B(CN)]4 (I, cAAC = 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) and its diborene relative, [(cAAC)(CN)B=B(CN)(cAAC)] (II), both react with disulfides and diselenides to yield the corresponding cAAC-supported cyanoboron bis(chalcogenides). Furthermore, reactions of I or II with elemental sulfur and selenium in various stoichiometries provided access to a variety of cAAC- stabilized cyanoboron-chalcogen heterocycles, including a unique dithiaborirane, a diboraselenirane, 1,3-dichalcogena-2,4-diboretanes, 1,3,4-trichalcogena- 2,5-diborolanes and a rare six-membered 1,2,4,5-tetrathia-3,6-diborinane. Stepwise addition reactions and solution stability studies provided insights into the mechanism of these reactions and the subtle differences in reactivity observed between I and II.}, language = {en} } @article{AuerhammerArrowsmithBraunschweigetal.2017, author = {Auerhammer, Dominic and Arrowsmith, Merle and Braunschweig, Holger and Dewhurst, Rian D. and Jim{\´e}nez-Halla, J. Oscar C. and Kupfer, Thomas}, title = {Nucleophilic addition and substitution at coordinatively saturated boron by facile 1,2-hydrogen shuttling onto a carbene donor}, series = {Chemical Science}, volume = {8}, journal = {Chemical Science}, number = {10}, doi = {10.1039/c7sc03193a}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170255}, pages = {7066-7071}, year = {2017}, abstract = {The reaction of [(cAAC\(^{Me}\))BH\(_{3}\)] (cAAC\(^{Me}\) = 1-(2,6-iPr\(_{2}\)C\(_{6}\)H\(_{3}\))-3,3,5,5-tetramethylpyrrolidin-2-ylidene) with a range of organolithium compounds led to the exclusive formation of the corresponding (dihydro)organoborates, Li\(^{+}\)[(cAAC\(^{Me}\)H)BH\(_{2}\)R]- (R = sp\(^{3}\)-, sp\(^{2}\)-, or sp-hybridised organic substituent), by migration of one boron-bound hydrogen atom to the adjacent carbene carbon of the cAAC ligand. A subsequent deprotonation/salt metathesis reaction with Me3SiCl or spontaneous LiH elimination yielded the neutral cAAC-supported mono(organo)boranes, [(cAAC\(^{Me}\)H)BH\(_{2}\)R]- (R]. Similarly the reaction of [cAAC\(^{Me}\))BH\(_{3}\)] with a neutral donor base L resulted in adduct formation by shuttling one boron-bound hydrogen to the cAAC ligand, to generate [(cAAC\(^{Me}\)H)BH\(_{2}\)L], either irreversibly (L = cAAC\(^{Me}\)) or reversibly (L = pyridine). Variable-temperature NMR data and DFT calculations on [(cAAC\(^{Me}\)H)BH\(_{2}\)(cAAC\(^{Me}\))] show that the hydrogen on the former carbene carbon atom exchanges rapidly with the boron-bound hydrides.}, language = {en} } @unpublished{AuerhammerArrowsmithBissingeretal.2017, author = {Auerhammer, Dominic and Arrowsmith, Merle and Bissinger, Philipp and Braunschweig, Holger and Dellermann, Theresa and Kupfer, Thomas and Lenczyk, Carsten and Roy, Dipak and Sch{\"a}fer, Marius and Schneider, Christoph}, title = {Increasing the Reactivity of Diborenes: Derivatization of NHC- Supported Dithienyldiborenes with Electron-Donor Groups}, series = {Chemistry, A European Journal}, journal = {Chemistry, A European Journal}, doi = {10.1002/chem.201704669}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-155419}, year = {2017}, abstract = {A series of NHC-supported 1,2-dithienyldiborenes was synthesized from the corresponding (dihalo)thienylborane NHC precursors. NMR and UV-vis spectroscopic data, as well as X-ray crystallographic analyses, were used to assess the electronic and steric influences on the B=B double bond of various NHCs and electron-donating substituents on the thienyl ligands. Crystallographic data showed that the degree of coplanarity of the diborene core and thienyl groups is highly dependent on the sterics of the substituents. Furthermore, any increase in the electron- donating ability of the substituents resulted in the destabilization of the HOMO and greater instability of the resulting diborenes.}, language = {en} } @unpublished{ArrowsmithMattockBoehnkeetal.2018, author = {Arrowsmith, Merle and Mattock, James D. and B{\"o}hnke, Julian and Krummenacher, Ivo and Vargas, Alfredo and Braunschweig, Holger}, title = {Direct access to a cAAC-supported dihydrodiborene and its dianion}, series = {Chemical Communications}, journal = {Chemical Communications}, doi = {10.1039/C8CC01580E}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-164276}, year = {2018}, abstract = {The two-fold reduction of (cAAC)BHX\(_2\) (cAAC = 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene; X = Cl, Br) provides a facile, high-yielding route to the dihydrodiborene (cAAC)\(_2\)B\(_2\)H\(_2\). The (chloro)hydroboryl anion reduction intermediate was successfully isolated using a crown ether. Overreduction of the diborene to its dianion [(cAAC)\(_2\)B\(_2\)H\(_2\)]\(^{2-}\) causes a decrease in the B-B bond order whereas the B-C bond orders increase.}, language = {en} } @article{ArrowsmithEndresHeinzetal.2021, author = {Arrowsmith, Merle and Endres, Sara and Heinz, Myron and Nestler, Vincent and Holthausen, Max C. and Braunschweig, Holger}, title = {Probing the Boundaries between Lewis-Basic and Redox Behavior of a Parent Borylene}, series = {Chemistry—A European Journal}, volume = {27}, journal = {Chemistry—A European Journal}, number = {70}, doi = {10.1002/chem.202103256}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-257154}, pages = {17660-17668}, year = {2021}, abstract = {The parent borylene (CAAC)(Me\(_{3}\)P)BH, 1 (CAAC=cyclic alkyl(amino)carbene), acts both as a Lewis base and one-electron reducing agent towards group 13 trichlorides (ECl\(_{3}\), E=B, Al, Ga, In), yielding the adducts 1-ECl\(_{3}\) and increasing proportions of the radical cation [1]\(^{•+}\) for the heavier group 13 analogues. With boron trihalides (BX\(_{3}\), X=F, Cl, Br, I) 1 undergoes sequential adduct formation and halide abstraction reactions to yield borylboronium cations and shows an increasing tendency towards redox processes for the heavier halides. Calculations confirm that 1 acts as a strong Lewis base towards EX3 and show a marked increase in the B-E bond dissociation energies down both group 13 and the halide group.}, language = {en} } @unpublished{ArrowsmithDoemlingSchmidtetal.2019, author = {Arrowsmith, Merle and D{\"o}mling, Michael and Schmidt, Uwe and Werner, Luis and Castro, Abril C. and Jim{\´e}nez-Halla, J. Oscar C. and M{\"u}ssig, Jonas and Prieschl, Dominic and Braunschweig, Holger}, title = {Spontaneous trans-Selective Transfer Hydrogenation of Apolar B=B Double Bonds}, series = {Angewandte Chemie, International Edition}, journal = {Angewandte Chemie, International Edition}, doi = {10.1002/anie.201902656}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-184874}, year = {2019}, abstract = {The transfer hydrogenation of NHC-supported diborenes with dimethylamine borane proceeds with high selectivity for the trans-1,2-dihydrodiboranes(6). DFT calculations suggest a stepwise proton-first-hydride-second reaction mechanism via an intermediate μ-hydrodiboronium dimethylaminoborate ion pair.}, language = {en} } @unpublished{ArrowsmithBoehnkeBraunschweigetal.2017, author = {Arrowsmith, Merle and B{\"o}hnke, Julian and Braunschweig, Holger and Deißenberger, Andrea and Dewhurst, Rian and Ewing, William and H{\"o}rl, Christian and Mies, Jan and Muessig, Jonas}, title = {Simple Solution-Phase Syntheses of Tetrahalodiboranes(4) and their Labile Dimethylsulfide Adducts}, series = {Chemical Communications}, volume = {53}, journal = {Chemical Communications}, doi = {10.1039/C7CC03148C}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-149438}, pages = {8265-8267}, year = {2017}, abstract = {Convenient, solution-phase syntheses of tetrahalodiboranes(4) B\(_2\)F\(_4\), B\(_2\)Cl\(_4\) and B\(_2\)I\(_4\) are presented herein from common precursor B\(_2\)Br\(_4\). In addition, the dimethylsulfide adducts B\(_2\)Cl\(_4\)(SMe\(_2\))\(_2\) and B\(_2\)Br\(_4\)(SMe\(_2\))\(_2\) are conveniently prepared in one-step syntheses from the commercially-available starting material B\(_2\)(NMe\(_2\))\(_4\). The results provide simple access to the full range of tetrahalodiboranes(4) for the exploration of their untapped synthetic potential.}, language = {en} } @article{ArrowsmithBoehnkeBraunschweigetal.2016, author = {Arrowsmith, Merle and B{\"o}hnke, Julian and Braunschweig, Holger and Celik, Mehmet and Dellermann, Theresa and Hammond, Kai}, title = {Uncatalyzed Hydrogenation of First-Row Main Group Multiple Bonds}, series = {Chemistry, A European Journal}, volume = {22}, journal = {Chemistry, A European Journal}, number = {48}, doi = {10.1002/chem.201604094}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-139364}, pages = {17169 -- 17172}, year = {2016}, abstract = {Room temperature hydrogenation of an SIDep-stabilized diboryne (SIDep = 1,3-bis(diethylphenyl)-4,5-dihydroimidazol-2-ylidene) and a CAAC-supported diboracumulene (CAAC = 1-(2,6- diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) provided the first selective route to the corresponding 1,2-dihydrodiborenes. DFT calculations showed an overall exothermic (ΔG = 19.4 kcal mol\(^{-1}\) two-step asynchronous H\(_2\) addition mechanism proceeding via a bridging hydride.}, subject = {Diborane}, language = {en} } @unpublished{ArrowsmithBoehnkeBraunschweigetal.2016, author = {Arrowsmith, Merle and B{\"o}hnke, Julian and Braunschweig, Holger and Celik, Mehmet and Claes, Christina and Ewing, William and Krummenacher, Ivo and Lubitz, Katharina and Schneider, Christoph}, title = {Neutral Diboron Analogues of Archetypal Aromatic Species by Spontaneous Cycloaddition}, doi = {10.1002/anie.201602384}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-142500}, pages = {4}, year = {2016}, abstract = {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+.}, subject = {Diborane}, language = {en} } @article{ArrowsmithBoehnkeBraunschweigetal.2016, author = {Arrowsmith, Merle and B{\"o}hnke, Julian and Braunschweig, Holger and Celik, Mehmet and Claes, Christina and Ewing, William and Krummenacher, Ivo and Lubitz, Katharina and Schneider, Christoph}, title = {Neutral Diboron Analogues of Archetypal Aromatic Species by Spontaneous Cycloaddition}, series = {Angewandte Chemie, International Edition}, volume = {55}, journal = {Angewandte Chemie, International Edition}, doi = {10.1002/anie.201602384}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-138226}, pages = {11271-11275}, year = {2016}, abstract = {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 6 π-aromatic dibora- benzene compound, a 2  π-aromatic triplet biradical 1,3-dibor- ete, and a phosphine-stabilized 2  π-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, C\(_6\)H\(_6\) and C\(_4\)H\(_4\)\(^{2+}\), and homoaromatic C\(_4\)H\(_5\)\(^+\).}, language = {en} } @unpublished{ArrowsmithBoehnkeBraunschweigetal.2017, author = {Arrowsmith, Merle and B{\"o}hnke, Julian and Braunschweig, Holger and Celik, Mehmet Ali}, title = {Reactivity of a Dihydrodiborene with CO: Coordination, Insertion, Cleavage and Spontaneous Cyclic Alkyne Formation}, series = {Angewandte Chemie, International Edition}, journal = {Angewandte Chemie, International Edition}, doi = {10.1002/anie.201707907}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-153318}, year = {2017}, abstract = {Under a CO atmosphere the dihydrodiborene [(cAAC)HB=BH(cAAC)] underwent coordination of CO concomitant with reversible hydrogen migration from boron to the carbene carbon atom, as well as reversible CO insertion into the B=B bond. Heating of the CO-adduct resulted in two unusual cAAC ring-expansion products, one presenting a B=C bond to a six-membered 1,2-azaborinane-3-ylidene, the other an unprecedented nine-membered cyclic alkyne resulting from reductive cleavage of CO and spontaneous C≡C triple bond formation.}, language = {en} } @unpublished{ArrowsmithBraunschweigStennett2017, author = {Arrowsmith, Merle and Braunschweig, Holger and Stennett, Tom}, title = {Formation and Reactivity of Electron-Precise B-B Single and Multiple Bonds}, series = {Angewandte Chemie, International Edition}, volume = {56}, journal = {Angewandte Chemie, International Edition}, number = {1}, doi = {10.1002/anie.201610072}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-145631}, pages = {96-115}, year = {2017}, abstract = {Recent years have seen rapid advances in the chemistry of small molecules containing electron-precise boron-boron bonds. This review provides an overview of the latest methods for the controlled synthesis of B-B single and multiple bonds as well as the ever-expanding range of reactivity displayed by the latter.}, language = {en} } @article{ArnoldBraunschweigGruss2011, author = {Arnold, Thomas and Braunschweig, Holger and Gruss, Katrin}, title = {cyclo-Tri-mu-oxido-tris{[(eta 5,eta 5)-1,2-bis(cyclopentadienyl)-1,1,2,2-tetramethyldisilane]zirconium(IV)}: a trimeric disila-bridged oxidozirconocene}, series = {Acta Crystallographica Section E: metal-organic compounds}, volume = {67}, journal = {Acta Crystallographica Section E: metal-organic compounds}, doi = {10.1107/S1600536811007094}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-134802}, pages = {M391-sup-23}, year = {2011}, abstract = {The title compound, [Zr(3)(C(14)H(20)Si(2))(3)O(3)], consists of three disila-bridged zirconocene units, which are connected via an oxide ligand, forming a nearly planar six-membered ring with a maximum displacement of 0.0191 (8) A. The compound was isolated as a by-product from a mixture of [(C(5)H(4)SiMe(2))(2)ZrCl(2)] and Li[AlH(4)] in Et(2)O.}, language = {en} } @article{ArnoldBraunschweigDamme2012, author = {Arnold, Nicole and Braunschweig, Holger and Damme, Alexander}, title = {Bis(μ-diisopropyl-phosphanido-\(κ^2\)P:P)bis-[hydrido(triisopropyl-phosphane-κP)platinum(II)]}, series = {Acta crystallographica. Section E, Structure reports online}, volume = {E68}, journal = {Acta crystallographica. Section E, Structure reports online}, doi = {http://dx.doi.org/10.1107/S1600536812022829}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-123723}, pages = {m808}, year = {2012}, abstract = {In the centrosymmetric molecular structure of the title compound \([Pt_2(C_6H_{14}P)_2H_2)(C_9H_{21}P)_2]\), each \(Pt^{II}\) atom is bound on one side to a phosphane ligand \((PiPr_3)\) and a hydrido ligand. On the other side, it is bound to two phosphanide ligands \((μ-PiPr_2)\), which engage a bridging position between the two \(Pt^{II}\) atoms, forming a distorted square-planar structure motif. The PtPt distance is 3.6755(2){\AA}. A comparable molecular structure was observed for bis-(μ-di-tert-butyl-phosphanido)bis-[hydrido(triethyl-phosphane)platinum(II)] [Itazaki et al. (2004 ). Organometallics, 23, 1610-1621].}, language = {en} } @article{AnsellKostakisBraunschweigetal.2016, author = {Ansell, Melvyn B. and Kostakis, George E. and Braunschweig, Holger and Navarro, Oscar and Spencer, John}, title = {Synthesis of functionalized hydrazines: facile homogeneous (N-heterocyclic carbene)-palladium(0)-catalyzed diboration and silaboration of azobenzenes}, series = {Advanced Synthesis \& Catalysis}, volume = {358}, journal = {Advanced Synthesis \& Catalysis}, number = {23}, doi = {10.1002/adsc.201601106}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-186582}, pages = {3765-3769}, year = {2016}, abstract = {The bis(N-heterocyclic carbene)(diphenylacetylene)palladium complex Pd(ITMe)\(_2\)(PhCCPh)] (ITMe=1,3,4,5-tetramethylimidazol-2-ylidene) acts as a highly active pre-catalyst in the diboration and silaboration of azobenzenes to synthesize a series of novel functionalized hydrazines. The reactions proceed using commercially available diboranes and silaboranes under mild reaction conditions.}, language = {en} }