Spectroscopic identification of an Fe(III) center, not Fe(IV), in the crystalline Sc-O-Fe adduct derived from [Fe(IV)(O)(TMC)]²⁺

J Am Chem Soc. 2015 Mar 18;137(10):3478-81. doi: 10.1021/jacs.5b00535. Epub 2015 Mar 6.

Abstract

The apparent Sc(3+) adduct of [Fe(IV)(O)(TMC)](2+) (1, TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) has been synthesized in amounts sufficient to allow its characterization by various spectroscopic techniques. Contrary to the earlier assignment of a +4 oxidation state for the iron center of 1, we establish that 1 has a high-spin iron(III) center based on its Mössbauer and EPR spectra and its quantitative reduction by 1 equiv of ferrocene to [Fe(II)(TMC)](2+). Thus, 1 is best described as a Sc(III)-O-Fe(III) complex, in agreement with previous DFT calculations (Swart, M. Chem. Commun. 2013, 49, 6650.). These results shed light on the interaction of Lewis acids with high-valent metal-oxo species.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Electron Spin Resonance Spectroscopy
  • Ferric Compounds / chemistry*
  • Iron / chemistry*
  • Models, Molecular
  • Molecular Conformation
  • Oxygen / chemistry*
  • Quantum Theory
  • Scandium / chemistry*
  • Spectroscopy, Mossbauer

Substances

  • Ferric Compounds
  • peroxo(1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane)iron(III)
  • Iron
  • Oxygen
  • Scandium