Main content area

Oxidative Addition of Carbon–Carbon Bonds with a Redox-Active Bis(imino)pyridine Iron Complex

Darmon, Jonathan M., Stieber, S. Chantal E., Sylvester, Kevin T., Fernández, Ignacio, Lobkovsky, Emil, Semproni, Scott P., Bill, Eckhard, Wieghardt, Karl, DeBeer, Serena, Chirik, Paul J.
Journal of the American Chemical Society 2012 v.134 no.41 pp. 17125-17137
X-radiation, X-ray diffraction, absorption, ambient temperature, anions, biphenyl, chemical bonding, chemical structure, ferric compounds, iron, ligands, nitrogen, nuclear magnetic resonance spectroscopy, oxidation, pyridines
Addition of biphenylene to the bis(imino)pyridine iron dinitrogen complexes, (ⁱᴾʳPDI)Fe(N₂)₂ and [(ᴹᵉPDI)Fe(N₂)]₂(μ₂-N₂) (ᴿPDI = 2,6-(2,6-R₂C₆H₃NCMe)₂C₅H₃N; R = Me, ⁱPr), resulted in oxidative addition of a CC bond at ambient temperature to yield the corresponding iron biphenyl compounds, (ᴿPDI)Fe(biphenyl). The molecular structures of the resulting bis(imino)pyridine iron metallacycles were established by X-ray diffraction and revealed idealized square pyramidal geometries. The electronic structures of the compounds were studied by Mössbauer spectroscopy, NMR spectroscopy, magnetochemistry, and X-ray absorption and X-ray emission spectroscopies. The experimental data, in combination with broken-symmetry density functional theory calculations, established spin crossover (low to intermediate spin) ferric compounds antiferromagnetically coupled to bis(imino)pyridine radical anions. Thus, the overall oxidation reaction involves cooperative electron loss from both the iron center and the redox-active bis(imino)pyridine ligand.