Electronic ground states of low-spin iron(III) porphyrinoids

Mikio Nakamura, Yoshiki Ohgo, Akira Ikezaki

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35 Citations (Scopus)


Six-coordinate low-spin iron(III) porphyrinates adopt either common (dxy)2(dxz, dyz)3 or less common (dxz, dyz)4(dxy)1 ground state. In this review article, three major factors that affect the electronic ground state have been examined. They are (i) nature of the axial ligand, (ii) electronic effect of peripheral substituents, and (iii) deformation of porphyrin ring. On the basis of the 1H NMR, 13C NMR, and EPR data, it is now clear that (i) the axial ligands with low-lying π* orbitals such as tert-butylisocyanide and 4-cyanopyridine, (ii) the electron donating groups at the meso-carbon atoms, and (iii) the ruffled deformation of porphyrin ring stabilize the (dxz, dyz)4(dxy)1 ground state. By manipulating these factors, we are able to prepare various low-spin iron(III) porphyrinates with unusual electronic structures such as bis(imidazole) complexes with the (dxz, dyz)4(dxy)1 ground state or bis(tert-butylisocyanide) complexes with the (dxy)2(dxz, dyz)3 ground state; bis(imidazole) and bis(tert-butylisocyanide) complexes usually adopt the (dxy)2(dxz, dyz)3 and (dxz, dyz)4(dxy)1 ground state, respectively.

Original languageEnglish
Pages (from-to)433-445
Number of pages13
JournalJournal of Inorganic Biochemistry
Issue number3
Publication statusPublished - 2008 Mar
Externally publishedYes


  • Deformation of porphyrin ring
  • EPR spectroscopy
  • Electronic effects of peripheral substituents
  • Electronic ground state axial ligands
  • Iron(III) porphyrinoids
  • Low-spin complexes
  • NMR spectroscopy

ASJC Scopus subject areas

  • Biochemistry
  • Inorganic Chemistry


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