173463-94-0Relevant articles and documents
Effects of boron doping on the structural and optoelectronic properties of 9,10-diarylanthracenes
Hoffend, Claas,Diefenbach, Martin,Januszewski, Estera,Bolte, Michael,Lerner, Hans-Wolfram,Holthausen, Max C.,Wagner, Matthias
, p. 13826 - 13837 (2013)
Key structural and optoelectronic properties of 9,10-dihydro-9,10- diboraanthracene (DBA) derivatives carrying mesityl (2a), 2-methylnaphthyl- (2b) and 9-phenyl-2,7-di-tert-butylanthryl (2c) substituents at the boron atoms have systematically been compared with the properties of their all-carbon congeners 4a-c. The experimental investigations have been augmented by quantum-chemical calculations. Steric repulsion leads to large dihedral angles between the aryl substituents and the DBA (2a-c) or anthrylene (4a-c) cores; as a result, the B-C bonds of 2a-c are kinetically shielded from hydrolysis and oxidative degradation. Lithium metal reduces the mesityl derivative 2a to the inverse sandwich complexes [Li(OR2)n]2[2a] (X-ray crystallography; OR2 = THF, n = 2; Et2O, n = 1). In line with the nodal structures of the LUMO of 2a/HOMO of [Li(THF)2] 2[2a], the C-C bond lengths of the anionic fragment [2a]2- show characteristic differences to those of 2a and come close to the C-C bond lengths of the isoelectronic species 4a. X-ray crystallography on anti-2b × 2 C6H6 and anti-4b × 2 C6H 6 reveals an essentially identical packing of the main molecules. The benzene solvate molecules, however, interact in a very different manner with anti-2b or anti-4b, which can be traced down to subtle disparities between the electron density distributions of the two compounds. 2a-c undergo a photoinduced aryl-to-DBA charge transfer; the back electron transfer results in blue (2a), green (2b) and red (2c) emission, albeit with low quantum yields. 4a-c are characterised by a local π-π* photoexcitation of the central 9,10-anthrylene fragments and corresponding blue emission. Each of the compounds 2a-c gives rise to two reversible DBA-centred one-electron transitions in the cyclic voltammogram.
Dual Role of Doubly Reduced Arylboranes as Dihydrogen- and Hydride-Transfer Catalysts
Von Grotthuss, Esther,Prey, Sven E.,Bolte, Michael,Lerner, Hans-Wolfram,Wagner, Matthias
supporting information, p. 6082 - 6091 (2019/04/17)
Doubly reduced 9,10-dihydro-9,10-diboraanthracenes (DBAs) are introduced as catalysts for hydrogenation as well as hydride-transfer reactions. The required alkali metal salts M2[DBA] are readily accessible from the respective neutral DBAs and Li metal, Na metal, or KC8. In the first step, the ambiphilic M2[DBA] activate H2 in a concerted, metal-like fashion. The rates of H2 activation strongly depend on the B-bonded substituents and the counter cations. Smaller substituents (e.g., H, Me) are superior to bulkier groups (e.g., Et, pTol), and a Mes substituent is even prohibitively large. Li+ ions, which form persistent contact ion pairs with [DBA]2-, slow the H2-addition rate to a higher extent than more weakly coordinating Na+/K+ ions. For the hydrogenation of unsaturated compounds, we identified Li2[4] (Me substituents at boron) as the best performing catalyst; its substrate scope encompasses Ph(H)C=NtBu, Ph2C=CH2, and anthracene. The conversion of E-Cl to E-H bonds (E = C, Si, Ge, P) was best achieved by using Na2[4]. The latter protocol provides facile access also to Me2Si(H)Cl, a most important silicone building block. Whereas the H2-transfer reaction regenerates the dianion [4]2- and is thus immediately catalytic, the H--transfer process releases the neutral 4, which has to be recharged by Na metal before it can enter the cycle again. To avoid Wurtz-type coupling of the substrate, the reduction of 4 must be performed in the absence of the element halide, which demands an alternating process management (similar to the industrial anthraquinone process).
Synthesis and Structures of 9,10-Dihydro-9,10-diboraanthracene Derivatives
Mueller, P.,Huck, S.,Koeppel, H.,Pritzkow, H.,Siebert, W.
, p. 1476 - 1484 (2007/10/03)
A series of alkyl and amino derivatives of the tricyclic organoborane system 9,10-dihydro-9,10-diboraanthracene was synthesized and examined.The reactions of 9,10-dichlor-9,10-dihydro-9,10-diboraanthracene (1a) with suitable reagents yield the corresponding alkyl, aryl or amino derivatives 1 c-h, respectively.The compounds have been characterized by 1H, 13C and 11B NMR spectroscopy.X-ray structure analyses have shown that the amino derivatives have bent structures, while the H2N compound 1h is planar.Calculations were carried out to study the reasons for the deformation of some of the amino-substituted derivatives.These calculations indicate that steric reasons are responsible for the deformation.Electrochemical investigations show reversible reductions of the dimethyl derivative 1c leading to the radical anion and the dianion.Both anions have been structurally characterized by X-ray diffraction studies. - Keywords: 9,10-Dihydro-9,10-diboraanthracenes, Organoboranes, Electrochemistry
