The parent borylene (CAAC)(Me P)BH, 1 (CAAC=cyclic alkyl(amino)carbene), acts both as a Lewis base and one-electron reducing agent towards group 13 trichlorides (ECl , E=B, Al, Ga, In), yielding the adducts 1-ECl and increasing proportions of the radical cation [1] for the heavier group 13 analogues. With boron trihalides (BX , 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 EX and show a marked increase in the B-E bond dissociation energies down both group 13 and the halide group.
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http://dx.doi.org/10.1002/chem.202103256 | DOI Listing |
J Am Chem Soc
March 2022
Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
Doubly N-heterocyclic-carbene-stabilized diborenes undergo facile reactions with CO, initially providing dibora-β-lactones. These lactones convert over time to their 2,4-diboraoxetan-3-one isomers through a presumed dissociative pathway and hypovalent boron species borylene carbonyls (LHB═C═O) and base-stabilized oxoboranes (LHB═O). Repeating these reactions with doubly cyclic(alkyl)(amino)carbene-stabilized diborenes allowed the isolation of a borylene carbonyl intermediate, whereas a base-stabilized oxoborane could be inferred by the isolation of a boroxine from the reaction mixture.
View Article and Find Full Text PDFChemistry
December 2021
Institute for Inorganic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
The parent borylene (CAAC)(Me P)BH, 1 (CAAC=cyclic alkyl(amino)carbene), acts both as a Lewis base and one-electron reducing agent towards group 13 trichlorides (ECl , E=B, Al, Ga, In), yielding the adducts 1-ECl and increasing proportions of the radical cation [1] for the heavier group 13 analogues. With boron trihalides (BX , 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 EX and show a marked increase in the B-E bond dissociation energies down both group 13 and the halide group.
View Article and Find Full Text PDFJ Am Chem Soc
August 2018
Institut für Anorganische Chemie , Julius-Maximilians Universität Würzburg, Am Hubland, 97074 Würzburg , Germany.
The desymmetrization of the cyclic (alkyl)(amino)carbene-supported diboracumulene B(cAAC) (cAAC = 1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidin-2-ylidene) by monoadduct formation with IMe (1,3-dimethylimidazol-2-ylidene) yields the zerovalent sp-sp diboron compound B(cAAC)(IMe), which provides a versatile platform for the synthesis of novel symmetrical and unsymmetrical zerovalent sp-sp diboron compounds by adduct formation with IMe and CO, respectively. Furthermore, B(cAAC)(IMe) displays enhanced reactivity compared to its symmetrical precursor, undergoing spontaneous intramolecular C-H activation and facile twofold hydrogenation, the latter resulting in B-B bond cleavage and the formation of the mixed-base parent borylene (cAAC)(IMe)BH.
View Article and Find Full Text PDFChemistry
April 2012
Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany.
The borylene complex [(OC)(5)Cr=B=N(SiMe(3))(2)] has been investigated by using threshold photoelectron-photoion coincidence spectroscopy with synchrotron radiation. The ionization energy of the parent complex and the 0 K appearance energies of the sequential CO loss channels have been determined. The derived bond-dissociation energies are used to discuss bonding and energetics in this compound.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
February 2012
Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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