meso Substituent Effects on the Geometric and Electronic Structures of High-Spin and Low-Spin Iron (III) Complexes of Mono-meso-Substituted Octaethylporphyrins

Heather Kalish, Jason E. Camp, Marcin Stȩpień, Lechoslaw Latos-Grazyński, Marilyn M. Olmstead, Alan L. Balch

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Introduction of a single meso substituent into ClFeIII(OEP) or K[(NC)2Fe(OEP)] results in significant changes in the geometric and/or spectroscopic properties of these complexes. The mono-meso-substituted iron(III) complexes ClFeIII(meso-Ph-OEP), ClFeIII(meso-n-Bu-OEP), ClFeIII(meso-MeO-OEP), ClFeIII(meso-Cl-OEP), ClFeIII(meso-NC-OEP), ClFeIII(meso-HC(O)-OEP), and ClFeIII(meso-O2N-OEP) have been isolated and characterized by their UV/vis and paramagnetically shifted 1H NMR spectra. The structures of both ClFeIII(meso-Ph-OEP) and ClFeIII(meso-NC-OEP) have been determined by X-ray crystallography. Both molecules have five-coordinate structures typical for high-spin (S = 5/2) iron(III) complexes. However, the porphyrins themselves no longer have the domed shape seen in ClFeIII(OEP), and the N4 coordination environment possesses a slight rectangular distortion. These high-spin, mono-meso-substituted iron(III) complexes display 1H NMR spectra in chloroform-d solution which indicate that the conformational changes seen in the solid-state structures are altered by normal molecular motion to produce spectra consistent with Cs molecular symmetry. In pyridine solution the high-spin six-coordinate complexes {(py)-ClFeIII(meso-R-OEP)} form. In methanol solution in the presence of excess potassium cyanide, the low-spin six-coordinate complexes K[(NC)2FeIII(meso-R-OEP)] form. The 1H NMR spectra of these show that electron-donating substituents produce an upfield relocation of the meso-proton chemical shifts. This relocation is interpreted in terms of increased contribution from the less common (dxz,dyz)4(dxy)1 ground electronic state as the meso substituent becomes more electron donating.

Original languageEnglish
Pages (from-to)989-997
Number of pages9
JournalInorganic Chemistry
Volume41
Issue number4
Early online date31 Jan 2002
DOIs
Publication statusPublished - 1 Feb 2002
Externally publishedYes

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Electronic structure
Relocation
Iron
Nuclear magnetic resonance
electronic structure
iron
relocation
Potassium Cyanide
nuclear magnetic resonance
Electrons
X ray crystallography
Porphyrins
Chemical shift
Electronic states
Chloroform
Methanol
Protons
cyanides
chloroform
porphyrins

Cite this

Kalish, Heather ; Camp, Jason E. ; Stȩpień, Marcin ; Latos-Grazyński, Lechoslaw ; Olmstead, Marilyn M. ; Balch, Alan L. / meso Substituent Effects on the Geometric and Electronic Structures of High-Spin and Low-Spin Iron (III) Complexes of Mono-meso-Substituted Octaethylporphyrins. In: Inorganic Chemistry. 2002 ; Vol. 41, No. 4. pp. 989-997.
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title = "meso Substituent Effects on the Geometric and Electronic Structures of High-Spin and Low-Spin Iron (III) Complexes of Mono-meso-Substituted Octaethylporphyrins",
abstract = "Introduction of a single meso substituent into ClFeIII(OEP) or K[(NC)2Fe(OEP)] results in significant changes in the geometric and/or spectroscopic properties of these complexes. The mono-meso-substituted iron(III) complexes ClFeIII(meso-Ph-OEP), ClFeIII(meso-n-Bu-OEP), ClFeIII(meso-MeO-OEP), ClFeIII(meso-Cl-OEP), ClFeIII(meso-NC-OEP), ClFeIII(meso-HC(O)-OEP), and ClFeIII(meso-O2N-OEP) have been isolated and characterized by their UV/vis and paramagnetically shifted 1H NMR spectra. The structures of both ClFeIII(meso-Ph-OEP) and ClFeIII(meso-NC-OEP) have been determined by X-ray crystallography. Both molecules have five-coordinate structures typical for high-spin (S = 5/2) iron(III) complexes. However, the porphyrins themselves no longer have the domed shape seen in ClFeIII(OEP), and the N4 coordination environment possesses a slight rectangular distortion. These high-spin, mono-meso-substituted iron(III) complexes display 1H NMR spectra in chloroform-d solution which indicate that the conformational changes seen in the solid-state structures are altered by normal molecular motion to produce spectra consistent with Cs molecular symmetry. In pyridine solution the high-spin six-coordinate complexes {(py)-ClFeIII(meso-R-OEP)} form. In methanol solution in the presence of excess potassium cyanide, the low-spin six-coordinate complexes K[(NC)2FeIII(meso-R-OEP)] form. The 1H NMR spectra of these show that electron-donating substituents produce an upfield relocation of the meso-proton chemical shifts. This relocation is interpreted in terms of increased contribution from the less common (dxz,dyz)4(dxy)1 ground electronic state as the meso substituent becomes more electron donating.",
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meso Substituent Effects on the Geometric and Electronic Structures of High-Spin and Low-Spin Iron (III) Complexes of Mono-meso-Substituted Octaethylporphyrins. / Kalish, Heather; Camp, Jason E.; Stȩpień, Marcin; Latos-Grazyński, Lechoslaw; Olmstead, Marilyn M.; Balch, Alan L.

In: Inorganic Chemistry, Vol. 41, No. 4, 01.02.2002, p. 989-997.

Research output: Contribution to journalArticle

TY - JOUR

T1 - meso Substituent Effects on the Geometric and Electronic Structures of High-Spin and Low-Spin Iron (III) Complexes of Mono-meso-Substituted Octaethylporphyrins

AU - Kalish, Heather

AU - Camp, Jason E.

AU - Stȩpień, Marcin

AU - Latos-Grazyński, Lechoslaw

AU - Olmstead, Marilyn M.

AU - Balch, Alan L.

PY - 2002/2/1

Y1 - 2002/2/1

N2 - Introduction of a single meso substituent into ClFeIII(OEP) or K[(NC)2Fe(OEP)] results in significant changes in the geometric and/or spectroscopic properties of these complexes. The mono-meso-substituted iron(III) complexes ClFeIII(meso-Ph-OEP), ClFeIII(meso-n-Bu-OEP), ClFeIII(meso-MeO-OEP), ClFeIII(meso-Cl-OEP), ClFeIII(meso-NC-OEP), ClFeIII(meso-HC(O)-OEP), and ClFeIII(meso-O2N-OEP) have been isolated and characterized by their UV/vis and paramagnetically shifted 1H NMR spectra. The structures of both ClFeIII(meso-Ph-OEP) and ClFeIII(meso-NC-OEP) have been determined by X-ray crystallography. Both molecules have five-coordinate structures typical for high-spin (S = 5/2) iron(III) complexes. However, the porphyrins themselves no longer have the domed shape seen in ClFeIII(OEP), and the N4 coordination environment possesses a slight rectangular distortion. These high-spin, mono-meso-substituted iron(III) complexes display 1H NMR spectra in chloroform-d solution which indicate that the conformational changes seen in the solid-state structures are altered by normal molecular motion to produce spectra consistent with Cs molecular symmetry. In pyridine solution the high-spin six-coordinate complexes {(py)-ClFeIII(meso-R-OEP)} form. In methanol solution in the presence of excess potassium cyanide, the low-spin six-coordinate complexes K[(NC)2FeIII(meso-R-OEP)] form. The 1H NMR spectra of these show that electron-donating substituents produce an upfield relocation of the meso-proton chemical shifts. This relocation is interpreted in terms of increased contribution from the less common (dxz,dyz)4(dxy)1 ground electronic state as the meso substituent becomes more electron donating.

AB - Introduction of a single meso substituent into ClFeIII(OEP) or K[(NC)2Fe(OEP)] results in significant changes in the geometric and/or spectroscopic properties of these complexes. The mono-meso-substituted iron(III) complexes ClFeIII(meso-Ph-OEP), ClFeIII(meso-n-Bu-OEP), ClFeIII(meso-MeO-OEP), ClFeIII(meso-Cl-OEP), ClFeIII(meso-NC-OEP), ClFeIII(meso-HC(O)-OEP), and ClFeIII(meso-O2N-OEP) have been isolated and characterized by their UV/vis and paramagnetically shifted 1H NMR spectra. The structures of both ClFeIII(meso-Ph-OEP) and ClFeIII(meso-NC-OEP) have been determined by X-ray crystallography. Both molecules have five-coordinate structures typical for high-spin (S = 5/2) iron(III) complexes. However, the porphyrins themselves no longer have the domed shape seen in ClFeIII(OEP), and the N4 coordination environment possesses a slight rectangular distortion. These high-spin, mono-meso-substituted iron(III) complexes display 1H NMR spectra in chloroform-d solution which indicate that the conformational changes seen in the solid-state structures are altered by normal molecular motion to produce spectra consistent with Cs molecular symmetry. In pyridine solution the high-spin six-coordinate complexes {(py)-ClFeIII(meso-R-OEP)} form. In methanol solution in the presence of excess potassium cyanide, the low-spin six-coordinate complexes K[(NC)2FeIII(meso-R-OEP)] form. The 1H NMR spectra of these show that electron-donating substituents produce an upfield relocation of the meso-proton chemical shifts. This relocation is interpreted in terms of increased contribution from the less common (dxz,dyz)4(dxy)1 ground electronic state as the meso substituent becomes more electron donating.

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U2 - 10.1021/ic011034q

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JF - Inorganic Chemistry

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