Reversible carbon-carbon bond formation induced by oxidation and reduction at a redox-active cobalt complex

Crisita Carmen Hojilla Atienza, Carsten Milsmann, Scott P. Semproni, Zoë R. Turner, Paul J. Chirik

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The electronic structure of the diamagnetic pyridine imine enamide cobalt dinitrogen complex, (iPrPIEA)CoN2 (iPrPIEA = 2-(2,6-iPr2-C6H3N=CMe)-6-(2,6- iPr2-C6H3NC=CH2)C 5H3N), was determined and is best described as a low-spin cobalt(II) complex antiferromagnetically coupled to an imine radical anion. Addition of potential radical sources such as NO, PhSSPh, or Ph3Cl resulted in C-C coupling at the enamide positions to form bimetallic cobalt compounds. Treatment with the smaller halocarbon, PhCH2Cl, again induced C-C coupling to form a bimetallic bis(imino)pyridine cobalt chloride product but also yielded a monomeric cobalt chloride product where the benzyl group added to the enamide carbon. Similar cooperative metal-ligand addition was observed upon treatment of (iPrPIEA)CoN2 with CH 2=CHCH2Br, which resulted in allylation of the enamide carbon. Reduction of Coupled-(iPrPDI)CoCl (Coupled-( iPrPDI)CoCl = [2-(2,6-iPr2-C6H 3N=CMe)-C5H3N-6-(2,6-iPr 2-C6H3N=CCH2-)CoCl]2) with NaBEt3H led to quantitative formation of (iPrPIEA) CoN2, demonstrating the reversibility of the C-C bond forming reactions. The electronic structures of each of the bimetallic cobalt products were also elucidated by a combination of experimental and computational methods.

Original languageEnglish (US)
Pages (from-to)5403-5417
Number of pages15
JournalInorganic Chemistry
Issue number9
StatePublished - May 6 2013

All Science Journal Classification (ASJC) codes

  • Inorganic Chemistry
  • Physical and Theoretical Chemistry


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