Reactivity of Two-Electron-Reduced Boron Formazanate Compounds with Electrophiles: Facile N-H/N-C Bond Homolysis Due to the Formation of Stable Ligand Radicals

Ranajit Mondol, Edwin Otten*

*Corresponding author for this work

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Abstract

The reactivity of a boron complex with a redoxactive formazanate ligand, LBPh2 [L = PhNNC(p-tol)NNPh], was studied. Two-electron reduction of this main-group complex generates the stable, nucleophilic dianion [LBPh2](2-), which reacts with the electrophiles BnBr and H2O to form products that derive from ligand benzylation and protonation, respectively. The resulting complexes are anionic boron analogues of leucoverdazyls. N-C and N-H bond homolysis of these compounds was studied by exchange NMR spectroscopy and kinetic experiments. The weak N-C and N-H bonds in these systems derive from the stability of the resulting borataverdazyl radical, in which the unpaired electron is delocalized over the four N atoms in the ligand backbone. We thus demonstrate the ability of this system to take up two electrons and an electrophile (E+ = Bn+, H+) in a process that takes place on the organic ligand. In addition, we show that the [2e(-)/E+] stored on the ligand can be converted to E-center dot radicals, reactivity that has implications in energy storage applications such as hydrogen evolution.

Original languageEnglish
Pages (from-to)9720-9727
Number of pages8
JournalInorganic Chemistry
Volume57
Issue number16
Early online date15-Feb-2018
DOIs
Publication statusPublished - 20-Aug-2018

Keywords

  • ELECTROCATALYTIC HYDROGEN EVOLUTION
  • COBALT-DITHIOLENE COMPLEXES
  • DENSITY-FUNCTIONAL THEORY
  • REDOX NON-INNOCENCE
  • H BOND
  • ELECTROCHEMICAL PROPERTIES
  • CYCLOADDITION CHEMISTRY
  • ALUMINUM(III) COMPLEX
  • DIFLUORIDE COMPLEXES
  • MOLECULAR CATALYSTS

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