Synthesis and characterization of the mixed-valence [Fe(II)Fe(III)BPLNP(OAc)2](BPh4)2 complex as a model for the reduced form of the purple acid phosphatase

J. Lee, D. J. Jung, H. J. Lee, K. B. Lee, Hwi Hur Nam Hwi Hur, Ho Gyeom Jang

Research output: Contribution to journalArticle

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Abstract

[Fe(II)Fe(III)BPLNP(OAc)2](BPh4)2 (1), a new model for the reduced form of the purple acid phosphatases, has been synthesized by using a dinucleating ligand, 2,6-bis[((2-pyridylmethyl)(6-methyl-2-pyridylmethyl)amino)methyl]-4-nitrophen ol (HBPLNP). Complex 1 has been studied by electronic spectral, NMR, EPR, SQUID, and electrochemical methods. Complex 1 exhibits two strong bands at 498 nm (ε = 2.6 x 103 M-1cm-1) and 1363 nm (ε = 5.7 x 102 M.-. in CH3CN. These are assigned to phenolate-to-Fe(III) and intervalence charge-transfer transitions, respectively. NMR spectrum of complex 1 exhibits sharp isotropically shifted resonances, which number is half of those expected for a valence-trapped species, indicating that electron transfer between Fe(II) and Fe(III) centers is faster than NMR time scale at room temperature. Complex 1 undergoes quasireversible one-electron redox processes. The Fe(III)2/Fe(II)Fe(III) and Fe(II)Fe(III)/Fe(II)2 redox couples are at 0.807 and 0.167 V versus SCE, respectively. It has K(comp) = 5.9 x 1010 representing that BPLNP/bis(acetato) ligand combination stabilizes a mixed-valence Fe(II)Fe(III) complex in the air. Interestingly, complex 1 exhibits intense EPR signals at g = 8.56, 5.45, 4.30 corresponding to mononuclear high-spin Fe(III) species, which suggest a very weak magnetic coupling between the iron centers. Magnetic susceptibility study shows that there is a very weak antiferromagnetic coupling (J = -0.78 cm-1, H = -2JS1· S2) between Fe(II) and Fe(III) centers. Thus, we can suggest that complex 1 has a very weak antiferromagnetic coupling between the iron centers due to the electronic effect of the nitro group in the bridging phenolate ligand.

Original languageEnglish
Pages (from-to)1025-1030
Number of pages6
JournalBulletin of the Korean Chemical Society
Volume21
Issue number10
Publication statusPublished - 2000 Oct 20

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Nuclear magnetic resonance
Ligands
Paramagnetic resonance
Iron
Magnetic couplings
Electrons
SQUIDs
Magnetic susceptibility
Charge transfer
Air
purple acid phosphatase
Temperature
Oxidation-Reduction
nitrofen

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

Synthesis and characterization of the mixed-valence [Fe(II)Fe(III)BPLNP(OAc)2](BPh4)2 complex as a model for the reduced form of the purple acid phosphatase. / Lee, J.; Jung, D. J.; Lee, H. J.; Lee, K. B.; Nam Hwi Hur, Hwi Hur; Jang, Ho Gyeom.

In: Bulletin of the Korean Chemical Society, Vol. 21, No. 10, 20.10.2000, p. 1025-1030.

Research output: Contribution to journalArticle

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title = "Synthesis and characterization of the mixed-valence [Fe(II)Fe(III)BPLNP(OAc)2](BPh4)2 complex as a model for the reduced form of the purple acid phosphatase",
abstract = "[Fe(II)Fe(III)BPLNP(OAc)2](BPh4)2 (1), a new model for the reduced form of the purple acid phosphatases, has been synthesized by using a dinucleating ligand, 2,6-bis[((2-pyridylmethyl)(6-methyl-2-pyridylmethyl)amino)methyl]-4-nitrophen ol (HBPLNP). Complex 1 has been studied by electronic spectral, NMR, EPR, SQUID, and electrochemical methods. Complex 1 exhibits two strong bands at 498 nm (ε = 2.6 x 103 M-1cm-1) and 1363 nm (ε = 5.7 x 102 M.-. in CH3CN. These are assigned to phenolate-to-Fe(III) and intervalence charge-transfer transitions, respectively. NMR spectrum of complex 1 exhibits sharp isotropically shifted resonances, which number is half of those expected for a valence-trapped species, indicating that electron transfer between Fe(II) and Fe(III) centers is faster than NMR time scale at room temperature. Complex 1 undergoes quasireversible one-electron redox processes. The Fe(III)2/Fe(II)Fe(III) and Fe(II)Fe(III)/Fe(II)2 redox couples are at 0.807 and 0.167 V versus SCE, respectively. It has K(comp) = 5.9 x 1010 representing that BPLNP/bis(acetato) ligand combination stabilizes a mixed-valence Fe(II)Fe(III) complex in the air. Interestingly, complex 1 exhibits intense EPR signals at g = 8.56, 5.45, 4.30 corresponding to mononuclear high-spin Fe(III) species, which suggest a very weak magnetic coupling between the iron centers. Magnetic susceptibility study shows that there is a very weak antiferromagnetic coupling (J = -0.78 cm-1, H = -2JS1· S2) between Fe(II) and Fe(III) centers. Thus, we can suggest that complex 1 has a very weak antiferromagnetic coupling between the iron centers due to the electronic effect of the nitro group in the bridging phenolate ligand.",
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T1 - Synthesis and characterization of the mixed-valence [Fe(II)Fe(III)BPLNP(OAc)2](BPh4)2 complex as a model for the reduced form of the purple acid phosphatase

AU - Lee, J.

AU - Jung, D. J.

AU - Lee, H. J.

AU - Lee, K. B.

AU - Nam Hwi Hur, Hwi Hur

AU - Jang, Ho Gyeom

PY - 2000/10/20

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N2 - [Fe(II)Fe(III)BPLNP(OAc)2](BPh4)2 (1), a new model for the reduced form of the purple acid phosphatases, has been synthesized by using a dinucleating ligand, 2,6-bis[((2-pyridylmethyl)(6-methyl-2-pyridylmethyl)amino)methyl]-4-nitrophen ol (HBPLNP). Complex 1 has been studied by electronic spectral, NMR, EPR, SQUID, and electrochemical methods. Complex 1 exhibits two strong bands at 498 nm (ε = 2.6 x 103 M-1cm-1) and 1363 nm (ε = 5.7 x 102 M.-. in CH3CN. These are assigned to phenolate-to-Fe(III) and intervalence charge-transfer transitions, respectively. NMR spectrum of complex 1 exhibits sharp isotropically shifted resonances, which number is half of those expected for a valence-trapped species, indicating that electron transfer between Fe(II) and Fe(III) centers is faster than NMR time scale at room temperature. Complex 1 undergoes quasireversible one-electron redox processes. The Fe(III)2/Fe(II)Fe(III) and Fe(II)Fe(III)/Fe(II)2 redox couples are at 0.807 and 0.167 V versus SCE, respectively. It has K(comp) = 5.9 x 1010 representing that BPLNP/bis(acetato) ligand combination stabilizes a mixed-valence Fe(II)Fe(III) complex in the air. Interestingly, complex 1 exhibits intense EPR signals at g = 8.56, 5.45, 4.30 corresponding to mononuclear high-spin Fe(III) species, which suggest a very weak magnetic coupling between the iron centers. Magnetic susceptibility study shows that there is a very weak antiferromagnetic coupling (J = -0.78 cm-1, H = -2JS1· S2) between Fe(II) and Fe(III) centers. Thus, we can suggest that complex 1 has a very weak antiferromagnetic coupling between the iron centers due to the electronic effect of the nitro group in the bridging phenolate ligand.

AB - [Fe(II)Fe(III)BPLNP(OAc)2](BPh4)2 (1), a new model for the reduced form of the purple acid phosphatases, has been synthesized by using a dinucleating ligand, 2,6-bis[((2-pyridylmethyl)(6-methyl-2-pyridylmethyl)amino)methyl]-4-nitrophen ol (HBPLNP). Complex 1 has been studied by electronic spectral, NMR, EPR, SQUID, and electrochemical methods. Complex 1 exhibits two strong bands at 498 nm (ε = 2.6 x 103 M-1cm-1) and 1363 nm (ε = 5.7 x 102 M.-. in CH3CN. These are assigned to phenolate-to-Fe(III) and intervalence charge-transfer transitions, respectively. NMR spectrum of complex 1 exhibits sharp isotropically shifted resonances, which number is half of those expected for a valence-trapped species, indicating that electron transfer between Fe(II) and Fe(III) centers is faster than NMR time scale at room temperature. Complex 1 undergoes quasireversible one-electron redox processes. The Fe(III)2/Fe(II)Fe(III) and Fe(II)Fe(III)/Fe(II)2 redox couples are at 0.807 and 0.167 V versus SCE, respectively. It has K(comp) = 5.9 x 1010 representing that BPLNP/bis(acetato) ligand combination stabilizes a mixed-valence Fe(II)Fe(III) complex in the air. Interestingly, complex 1 exhibits intense EPR signals at g = 8.56, 5.45, 4.30 corresponding to mononuclear high-spin Fe(III) species, which suggest a very weak magnetic coupling between the iron centers. Magnetic susceptibility study shows that there is a very weak antiferromagnetic coupling (J = -0.78 cm-1, H = -2JS1· S2) between Fe(II) and Fe(III) centers. Thus, we can suggest that complex 1 has a very weak antiferromagnetic coupling between the iron centers due to the electronic effect of the nitro group in the bridging phenolate ligand.

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