Electronic structure of highly ruffled low-spin iron(III) porphyrinates with electron withdrawing heptafluoropropyl groups at the meso positions

Akira Tozuka, Yoshiki Ohgo, Akira Ikezaki, Miyoko Taniguchi, Mikio Nakamura

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Bis(pyridine)[meso-tetrakis(heptafluoropropyl)porphyrinato]iron(III), [Fe(THFPrP)Py2]+, was reported to be the low-spin complex that adopts the purest (dxz, dyz)4(d xy)1ground state where the energy gap between the iron dxyand dπ(dxz, dyz) orbitals is larger than the corresponding energy gaps of any other complexes reported previously (Moore, K. T.; Fletcher, J. T.; Therien, M. J. J. Am. Chem. Soc. 1999, 121, 5196-5209). Although the highly ruffled porphyrin core expected for this complex contributes to the stabilization of the (dxz, d yz)4(dxy)1ground state, the strongly electron withdrawing C3F7groups at the meso positions should stabilize the (dxy)2(dxz, d yz)3ground state. Thus, we have reexamined the electronic structure of [Fe(THFPrP)Py2]+by means of 1H NMR, 19F NMR, and electron paramagnetic resonance (EPR) spectroscopy. The CD2Cl2solution of [Fe(THFPrP)Py2] +shows the pyrrole-H signal at-10.25 ppm (298 K) in 1H NMR, the CF2(α) signal at-74.6 ppm (298 K) in 19F NMR, and the large gmaxtype signal at g = 3.16 (4.2 K) in the EPR. Thus, contrary to the previous report, the complex is unambiguously shown to adopt the (dxy)2(dxz, dyz) 3ground state. Comparison of the spectroscopic data of a series of [Fe(THFPrP)L2]+with those of the corresponding meso-tetrapropylporphyrin complexes [Fe(TPrP)L2]+with various axial ligands (L) has shown that the meso-C3F 7groups stabilize the (dxy)2(dxz, dyz)3ground state. Therefore, it is clear that the less common (dxz, dyz)4(dxy) 1ground state can be stabilized by the three major factors: (i) axial ligand with low-lying π* orbitals, (ii) ruffled porphyrin ring, and (iii) electron donating substituent at the meso position.

Original languageEnglish
Pages (from-to)10400-10408
Number of pages9
JournalInorganic Chemistry
Volume49
Issue number22
DOIs
Publication statusPublished - 2010 Nov 15
Externally publishedYes

Fingerprint

Electronic structure
Iron
Nuclear magnetic resonance
electronic structure
iron
nuclear magnetic resonance
Electrons
Porphyrins
porphyrins
Paramagnetic resonance
electron paramagnetic resonance
Energy gap
electrons
Ligands
orbitals
ligands
Pyrroles
pyrroles
pyridines
Stabilization

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Physical and Theoretical Chemistry

Cite this

Electronic structure of highly ruffled low-spin iron(III) porphyrinates with electron withdrawing heptafluoropropyl groups at the meso positions. / Tozuka, Akira; Ohgo, Yoshiki; Ikezaki, Akira; Taniguchi, Miyoko; Nakamura, Mikio.

In: Inorganic Chemistry, Vol. 49, No. 22, 15.11.2010, p. 10400-10408.

Research output: Contribution to journalArticle

Tozuka, Akira ; Ohgo, Yoshiki ; Ikezaki, Akira ; Taniguchi, Miyoko ; Nakamura, Mikio. / Electronic structure of highly ruffled low-spin iron(III) porphyrinates with electron withdrawing heptafluoropropyl groups at the meso positions. In: Inorganic Chemistry. 2010 ; Vol. 49, No. 22. pp. 10400-10408.
@article{ed654772bcda4bcc9d56ff7dd89466d1,
title = "Electronic structure of highly ruffled low-spin iron(III) porphyrinates with electron withdrawing heptafluoropropyl groups at the meso positions",
abstract = "Bis(pyridine)[meso-tetrakis(heptafluoropropyl)porphyrinato]iron(III), [Fe(THFPrP)Py2]+, was reported to be the low-spin complex that adopts the purest (dxz, dyz)4(d xy)1ground state where the energy gap between the iron dxyand dπ(dxz, dyz) orbitals is larger than the corresponding energy gaps of any other complexes reported previously (Moore, K. T.; Fletcher, J. T.; Therien, M. J. J. Am. Chem. Soc. 1999, 121, 5196-5209). Although the highly ruffled porphyrin core expected for this complex contributes to the stabilization of the (dxz, d yz)4(dxy)1ground state, the strongly electron withdrawing C3F7groups at the meso positions should stabilize the (dxy)2(dxz, d yz)3ground state. Thus, we have reexamined the electronic structure of [Fe(THFPrP)Py2]+by means of 1H NMR, 19F NMR, and electron paramagnetic resonance (EPR) spectroscopy. The CD2Cl2solution of [Fe(THFPrP)Py2] +shows the pyrrole-H signal at-10.25 ppm (298 K) in 1H NMR, the CF2(α) signal at-74.6 ppm (298 K) in 19F NMR, and the large gmaxtype signal at g = 3.16 (4.2 K) in the EPR. Thus, contrary to the previous report, the complex is unambiguously shown to adopt the (dxy)2(dxz, dyz) 3ground state. Comparison of the spectroscopic data of a series of [Fe(THFPrP)L2]+with those of the corresponding meso-tetrapropylporphyrin complexes [Fe(TPrP)L2]+with various axial ligands (L) has shown that the meso-C3F 7groups stabilize the (dxy)2(dxz, dyz)3ground state. Therefore, it is clear that the less common (dxz, dyz)4(dxy) 1ground state can be stabilized by the three major factors: (i) axial ligand with low-lying π* orbitals, (ii) ruffled porphyrin ring, and (iii) electron donating substituent at the meso position.",
author = "Akira Tozuka and Yoshiki Ohgo and Akira Ikezaki and Miyoko Taniguchi and Mikio Nakamura",
year = "2010",
month = "11",
day = "15",
doi = "10.1021/ic101184y",
language = "English",
volume = "49",
pages = "10400--10408",
journal = "Inorganic Chemistry",
issn = "0020-1669",
publisher = "American Chemical Society",
number = "22",

}

TY - JOUR

T1 - Electronic structure of highly ruffled low-spin iron(III) porphyrinates with electron withdrawing heptafluoropropyl groups at the meso positions

AU - Tozuka, Akira

AU - Ohgo, Yoshiki

AU - Ikezaki, Akira

AU - Taniguchi, Miyoko

AU - Nakamura, Mikio

PY - 2010/11/15

Y1 - 2010/11/15

N2 - Bis(pyridine)[meso-tetrakis(heptafluoropropyl)porphyrinato]iron(III), [Fe(THFPrP)Py2]+, was reported to be the low-spin complex that adopts the purest (dxz, dyz)4(d xy)1ground state where the energy gap between the iron dxyand dπ(dxz, dyz) orbitals is larger than the corresponding energy gaps of any other complexes reported previously (Moore, K. T.; Fletcher, J. T.; Therien, M. J. J. Am. Chem. Soc. 1999, 121, 5196-5209). Although the highly ruffled porphyrin core expected for this complex contributes to the stabilization of the (dxz, d yz)4(dxy)1ground state, the strongly electron withdrawing C3F7groups at the meso positions should stabilize the (dxy)2(dxz, d yz)3ground state. Thus, we have reexamined the electronic structure of [Fe(THFPrP)Py2]+by means of 1H NMR, 19F NMR, and electron paramagnetic resonance (EPR) spectroscopy. The CD2Cl2solution of [Fe(THFPrP)Py2] +shows the pyrrole-H signal at-10.25 ppm (298 K) in 1H NMR, the CF2(α) signal at-74.6 ppm (298 K) in 19F NMR, and the large gmaxtype signal at g = 3.16 (4.2 K) in the EPR. Thus, contrary to the previous report, the complex is unambiguously shown to adopt the (dxy)2(dxz, dyz) 3ground state. Comparison of the spectroscopic data of a series of [Fe(THFPrP)L2]+with those of the corresponding meso-tetrapropylporphyrin complexes [Fe(TPrP)L2]+with various axial ligands (L) has shown that the meso-C3F 7groups stabilize the (dxy)2(dxz, dyz)3ground state. Therefore, it is clear that the less common (dxz, dyz)4(dxy) 1ground state can be stabilized by the three major factors: (i) axial ligand with low-lying π* orbitals, (ii) ruffled porphyrin ring, and (iii) electron donating substituent at the meso position.

AB - Bis(pyridine)[meso-tetrakis(heptafluoropropyl)porphyrinato]iron(III), [Fe(THFPrP)Py2]+, was reported to be the low-spin complex that adopts the purest (dxz, dyz)4(d xy)1ground state where the energy gap between the iron dxyand dπ(dxz, dyz) orbitals is larger than the corresponding energy gaps of any other complexes reported previously (Moore, K. T.; Fletcher, J. T.; Therien, M. J. J. Am. Chem. Soc. 1999, 121, 5196-5209). Although the highly ruffled porphyrin core expected for this complex contributes to the stabilization of the (dxz, d yz)4(dxy)1ground state, the strongly electron withdrawing C3F7groups at the meso positions should stabilize the (dxy)2(dxz, d yz)3ground state. Thus, we have reexamined the electronic structure of [Fe(THFPrP)Py2]+by means of 1H NMR, 19F NMR, and electron paramagnetic resonance (EPR) spectroscopy. The CD2Cl2solution of [Fe(THFPrP)Py2] +shows the pyrrole-H signal at-10.25 ppm (298 K) in 1H NMR, the CF2(α) signal at-74.6 ppm (298 K) in 19F NMR, and the large gmaxtype signal at g = 3.16 (4.2 K) in the EPR. Thus, contrary to the previous report, the complex is unambiguously shown to adopt the (dxy)2(dxz, dyz) 3ground state. Comparison of the spectroscopic data of a series of [Fe(THFPrP)L2]+with those of the corresponding meso-tetrapropylporphyrin complexes [Fe(TPrP)L2]+with various axial ligands (L) has shown that the meso-C3F 7groups stabilize the (dxy)2(dxz, dyz)3ground state. Therefore, it is clear that the less common (dxz, dyz)4(dxy) 1ground state can be stabilized by the three major factors: (i) axial ligand with low-lying π* orbitals, (ii) ruffled porphyrin ring, and (iii) electron donating substituent at the meso position.

UR - http://www.scopus.com/inward/record.url?scp=78149291370&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=78149291370&partnerID=8YFLogxK

U2 - 10.1021/ic101184y

DO - 10.1021/ic101184y

M3 - Article

VL - 49

SP - 10400

EP - 10408

JO - Inorganic Chemistry

JF - Inorganic Chemistry

SN - 0020-1669

IS - 22

ER -