Dokument-ID Dokumenttyp Verfasser/Autoren Herausgeber Haupttitel Abstract Auflage Verlagsort Verlag Erscheinungsjahr Seitenzahl Schriftenreihe Titel Schriftenreihe Bandzahl ISBN Quelle der Hochschulschrift Konferenzname Quelle:Titel Quelle:Jahrgang Quelle:Heftnummer Quelle:Erste Seite Quelle:Letzte Seite URN DOI Abteilungen OPUS4-16025 unpublished Stennett, Tom; Mattock, James; Vollert, Ivonne; Vargas, Alfredo; Braunschweig, Holger Unsymmetrical, Cyclic Diborenes and Thermal Rearrangement to a Borylborylene Cyclic diboranes(4) based on a chelating monoanionic, benzylphosphine linker were prepared by boron-silicon exchange between arylsilanes and B\(_2\)Br\(_4\). Coordination of Lewis bases to the remaining sp\(^2\) boron atom yielded unsymmetrical sp\(^3\)-sp\(^3\) diboranes, which were reduced with KC\(_8\) to their corresponding trans-diborenes. These compounds were studied by a combination of spectroscopic methods, X-ray diffraction and DFT calculations. PMe\(_3\)-stabilized diborene 6 was found to undergo thermal rearrangement to gem- diborene 8. DFT calculations on 8 reveal a polar boron-boron bond, and indicate that the compound is best described as a borylborylene. 2018 4098-4102 Angewandte Chemie, International Edition 57 urn:nbn:de:bvb:20-opus-160258 10.1002/anie.201800671 Institut für Anorganische Chemie OPUS4-15305 unpublished Wang, Sunewang Rixin; Arrowsmith, Merle; Braunschweig, Holger; Dewhurst, Rian; Dömling, Michael; Mattock, James; Pranckevicius, Conor; Vargas, Alfredo Monomeric 16-Electron π-Diborene Complexes of Zn(II) and Cd(II) Despite the prevalence of stable π-complexes of most d\(^{10}\) metals, such as Cu(I) and Ni(0), with ethylene and other olefins, complexation of d\(^{10}\) Zn(II) to simple olefins is too weak to form isolable complexes due to the metal ion's limited capacity for π-backdonation. By employing more strongly donating π- ligands, namely neutral diborenes with a high-lying π(B=B) or- bital, monomeric 16-electron M(II)-diborene (M = Zn, Cd) π- complexes were synthesized in good yields. Metal-B2 π- interactions in both the solid and solution state were confirmed by single-crystal X-ray analyses and their solution NMR and UV-vis absorption spectroscopy, respectively. The M(II) centers adopt a trigonal planar geometry and interact almost symmetrically with both boron atoms. The MB2 planes significantly twist out of the MX\(_2\) planes about the M-centroid(B-B) vector, with angles rang- ing from 47.0° to 85.5°, depending on the steric interactions be- tween the diborene ligand and the MX\(_2\) fragment. 2017 Journal of the American Chemical Society urn:nbn:de:bvb:20-opus-153058 10.1021/jacs.7b06644 Institut für Anorganische Chemie OPUS4-14198 unpublished Braunschweig, Holger; Krummenacher, Ivo; Lichtenberg, Crispin; Mattock, James; Schäfer, Marius; Schmidt, Uwe; Schneider, Christoph; Steffenhagen, Thomas; Ullrich, Stefan; Vargas, Alfredo Dibora[2]ferrocenophane: A Carbene-Stabilized Diborene in a Strained cis-Configuration 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. 2016 9 Angewandte Chemie, International Edition urn:nbn:de:bvb:20-opus-141981 10.1002/anie.201609601 Institut für Anorganische Chemie OPUS4-17826 unpublished Stennett, Tom; Mattock, James; Pentecost, Leanne; Vargas, Alfredo; Braunschweig, Holger Chelated Diborenes and their Inverse-Electron-Demand Diels- Alder Reactions with Dienes A doubly base-stabilized diborane based on a benzylphosphine linker was prepared by a salt elimination reaction between 2-LiC\(_6\)H\(_4\)CH\(_2\)PCy\(_2\).Et\(_2\)O and B\(_2\)Br\(_4\). This compound was reduced with KC8 to its corresponding diborene, with the benzylphosphine forming a five-membered chelate. The diborene reacts with butadiene, 2-trimethylsiloxy-1,3-butadiene and isoprene to form 4,5-diboracyclohexenes, which interconvert between their 1,1- (geminal) and 1,2- (vicinal) chelated isomers. The 1,1-chelated diborene undergoes a halide-catalysed isomerisation into its thermodynamically favoured 1,2-isomer, which undergoes Diels-Alder reactions more slowly than the kinetic product. 2018 Angewandte Chemie, International Edition urn:nbn:de:bvb:20-opus-178268 10.1002/anie.201809217 Institut für Anorganische Chemie