4151-78-4Relevant academic research and scientific papers
Oxygen-Oxygen Bond Cleavage and Formation in Co(II)-Mediated Stoichiometric O2 Reduction via the Potential Intermediacy of a Co(IV) Oxyl Radical
Nurdin, Lucie,Spasyuk, Denis M.,Fairburn, Laura,Piers, Warren E.,Maron, Laurent
supporting information, p. 16094 - 16105 (2018/11/27)
In reactions of significance to alternative energy schemes, metal catalysts are needed to overcome kinetically and thermodynamically difficult processes. Often, high-oxidation-state, high-energy metal oxo intermediates are proposed as mediators in elementary steps involving O-O bond cleavage and formation, but the mechanisms of these steps are difficult to study because of the fleeting nature of these species. Here we utilized a novel dianionic pentadentate ligand system that enabled a detailed mechanistic investigation of the protonation of a cobalt(III)-cobalt(III) peroxo dimer, a known intermediate in oxygen reduction catalysis to hydrogen peroxide. It was shown that double protonation occurs rapidly and leads to a low-energy O-O bond cleavage step that generates a Co(III) aquo complex and a highly reactive Co(IV) oxyl cation. The latter was probed computationally and experimentally implicated through chemical interception and isotope labeling experiments. In the absence of competing chemical reagents, it dimerizes and eliminates dioxygen in a step highly relevant to O-O bond formation in the oxygen evolution step in water oxidation. Thus, the study demonstrates both facile O-O bond cleavage and formation in the stoichiometric reduction of O2 to H2O with 2 equiv of Co(II) and suggests a new pathway for selective reduction of O2 to water via Co(III)-O-O-Co(III) peroxo intermediates.
Multiply borylated arenes: X-ray crystal structure analyses and quantum chemical calculations
Haberecht, Monika C.,Heilmann, Julia B.,Haghiri, Alireza,Bolte, Michael,Bats, Jan W.,Lerner, Hans-Wolfram,Holthausen, Max C.,Wagner, Matthias
, p. 904 - 913 (2008/10/09)
Optimised synthesis procedures and results of X-ray single crystal structure analyses for 4-(dibromoboryl)toluene, 1,3-bis(dibromoboryl)benzene, 1,4-bis(dibromoboryl)benzene, and 1,3,5-tris(dibromoboryl)benzene are reported. These compounds have also been studied by Hartree-Fock (HF), density functional theory (DFT), and Moller-Plesset second-order perturbation (MP2) methods in combination with the polarized double-ζ valence (SVP) and polarized triple-ζ valence (TZVP) basis sets of Ahlrichs and coworkers. A comparison of the quantum chemical results for optimised geometries and computed NMR chemical shifts with experiment is presented to test the quality of the various methods for this class of compounds. All DFT methods tested yield optimised geometries within the experimental error bars of 3σ for bond lengths, whereas larger deviations among the methods are observed for computed NMR chemical shifts. This calibration recommends the B3LYP/SVP combination as a reliable and computationally efficient level of theory to assess the structures and absolute and relative 1H-, 13C- and 11B NMR shift values of borylated aromatic compounds in future investigations.
Synthesis and characterization of triarylborthiins, Ar3B3S3 (Ar=4-MeC6H4, 3-MeC6H4, 2-MeC6H4, 4-EtC6H4, and 3,5-Me2C6H3)
Beckett, Michael A.,Minton, Paul R.,Werschkun, Barbara
, p. 37 - 42 (2007/10/02)
The air/moisture-sensitive triarylborthiins, Ar3B3S3 (Ar=4-MeC6H4, 3-MeC6H4, 2-MeC6H4, 4-EtC6H4, and 3,5-Me2C6H3), have been prepared by the reaction of ArBBr2 with HgS in benzene at reflux and have been characterized by 11B NMR and IR spectroscopy and ma
Darstellung von Arylhalogenboranen
Haubold, Wolfgang,Herdtle, Joerg,Gollinger, Walter,Einholz, Wolfgang
, p. 1 - 8 (2007/10/02)
In a ligand-exchange reaction between aryltrimethylsilanes, (ArSiMe3) and halogenboranes, (BX3 or ArBX2), arylhalogenboranes (ArBX2, ArAr'BX or Ar2BX) and halogentrimethylsilane are formed.This transfer of substituted aromatic groups from a silicon to a boron atom is an efficient synthetic pathway for the preparation of the corresponding arylhalogenboranes and diarylhalogenboranes with different aryl groups.Physical properties and spectroscopical data of the new arylhalogenboranes are given.
A New Borylation Method for Alkylbenzene and Polystyrene
Paetzold, Peter,Hoffmann, Juergen
, p. 3724 - 3733 (2007/10/02)
The borylation of alkylbenzenes by Hal2BH (Hal = F, Cl, Br) gives H2 and a mixture of m- and p-alkyl(dihaloboryl)benzenes.In the case of bulky alkyl groups, such as isopropyl, tert-butyl, these are partially split off as R - H and RBHal2.The phenyl groups in polystyrene-divinylbenzene copolymers undergo borylation with Br2BH in a 55percent yield.
