Oxidative Addition of Dihydrogen, Boron Compounds, and Aryl Halides to a Cobalt(I) Cation Supported by a Strong-Field Pincer Ligand

Stephan M. Rummelt, Hongyu Zhong, Nadia G. Léonard, Scott P. Semproni, Paul J. Chirik

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Abstract

Cationic cobalt(I) dinitrogen complexes with a strong-field tridentate pincer ligand were prepared, and the oxidative addition of polar and nonpolar bonds was studied. Addition of H 2 to [( iPr PNP)Co(N 2 )] + ( iPr PNP = 2,6-bis((diisopropylphosphaneyl)methyl)pyridine) in deuterated tetrahydrofuran (THF) resulted in rapid oxidative addition and formation of the cis-Co(III) dihydride complex, cis-[( iPr PNP)Co(H) 2 L] + , where L = THF or N 2 . The addition of H 2 was reversible as evidenced by the dynamics observed by variable-temperature 1 H NMR spectroscopy and the regeneration of [( iPr PNP)Co(N 2 )] + upon exposure to dinitrogen. In contrast, addition of HBPin (Pin = pinacolato), B 2 Pin 2 , and aryl halides resulted in the formation of net one-electron oxidation products: cationic Co(II)-boryl and Co(II)-halide/aryl complexes, respectively. All products were structurally characterized by X-ray crystallography, and the electronic structures were determined by a combination of magnetic moment measurements, electron paramagnetic resonance spectroscopy, and density functional theory calculations. Monitoring the addition of HBPin to [( iPr PNP)Co(N 2 )] + provided evidence for a transient Co(III) oxidative addition product that likely undergoes comproportionation with the cobalt(I) starting material to generate the observed Co(II) products.

Original languageEnglish (US)
Pages (from-to)1081-1090
Number of pages10
JournalOrganometallics
Volume38
Issue number5
DOIs
StatePublished - Mar 11 2019

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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