Low-energy catechol to cobalt(III) electron transfer in the cobaloxime-catalyzed oxidation of 3,5-di-tert-butylcatechol

László I. Simándi, Teréz Barna, G. Argay, Tatiana L. Simándi

Research output: Article

42 Citations (Scopus)

Abstract

Intermediates of the catalytic oxidation of 3,5-di-tert-butylcatechol (3,5-DTBCatH2) by O2 in the presence of (triphenylphosphine)bis(dimethylglyoximato)cobalt(II) as catalyst have been studied. The complex [Co(Hdmg)2-(Ph3P)(3,5-DTBCatH)] has been isolated from the reaction mixture and characterized by X-ray diffraction (monoclinic, P21/c, a = 16.498(1) Å, b = 9.254(1) Å, c = 26.038(2) Å, β = 103.59(1)°, V = 3864.0(4) Å3, Dc = 1.33 g cm-3, Z = 4, μ(Cu Kα) = 44.4 cm-1, R = 0.0480). It contains a unidentate 3,5-di-tert-butylcatecholato-(1-) ligand. Upon dissolution and warming in benzene under N2, homolytic Co-O bond cleavage produces cobaloxime(II) and the free 3,5-di-tert-butylsemiquinonato(1-) anion radical, as demonstrated by ESR spectroscopy. In O2-containing solution, the complex restarts the catalytic reaction, during which the [CoIII(Hdmg)2(Ph3P)(3,5-DTBSQ•)] species can also be detected by ESR. The observed behavior is rationalized by a mechanism incorporating the intermediates identified.

Original languageEnglish
Pages (from-to)6337-6340
Number of pages4
JournalInorganic Chemistry
Volume34
Issue number25
Publication statusPublished - 1995

Fingerprint

Cobalt
Paramagnetic resonance
electron transfer
cobalt
Oxidation
oxidation
Electrons
Catalytic oxidation
Benzene
Anions
cleavage
dissolving
Dissolution
benzene
Spectroscopy
anions
Ligands
catalysts
X ray diffraction
ligands

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

Low-energy catechol to cobalt(III) electron transfer in the cobaloxime-catalyzed oxidation of 3,5-di-tert-butylcatechol. / Simándi, László I.; Barna, Teréz; Argay, G.; Simándi, Tatiana L.

In: Inorganic Chemistry, Vol. 34, No. 25, 1995, p. 6337-6340.

Research output: Article

Simándi, László I. ; Barna, Teréz ; Argay, G. ; Simándi, Tatiana L. / Low-energy catechol to cobalt(III) electron transfer in the cobaloxime-catalyzed oxidation of 3,5-di-tert-butylcatechol. In: Inorganic Chemistry. 1995 ; Vol. 34, No. 25. pp. 6337-6340.
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abstract = "Intermediates of the catalytic oxidation of 3,5-di-tert-butylcatechol (3,5-DTBCatH2) by O2 in the presence of (triphenylphosphine)bis(dimethylglyoximato)cobalt(II) as catalyst have been studied. The complex [Co(Hdmg)2-(Ph3P)(3,5-DTBCatH)] has been isolated from the reaction mixture and characterized by X-ray diffraction (monoclinic, P21/c, a = 16.498(1) {\AA}, b = 9.254(1) {\AA}, c = 26.038(2) {\AA}, β = 103.59(1)°, V = 3864.0(4) {\AA}3, Dc = 1.33 g cm-3, Z = 4, μ(Cu Kα) = 44.4 cm-1, R = 0.0480). It contains a unidentate 3,5-di-tert-butylcatecholato-(1-) ligand. Upon dissolution and warming in benzene under N2, homolytic Co-O bond cleavage produces cobaloxime(II) and the free 3,5-di-tert-butylsemiquinonato(1-) anion radical, as demonstrated by ESR spectroscopy. In O2-containing solution, the complex restarts the catalytic reaction, during which the [CoIII(Hdmg)2(Ph3P)(3,5-DTBSQ•)] species can also be detected by ESR. The observed behavior is rationalized by a mechanism incorporating the intermediates identified.",
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N2 - Intermediates of the catalytic oxidation of 3,5-di-tert-butylcatechol (3,5-DTBCatH2) by O2 in the presence of (triphenylphosphine)bis(dimethylglyoximato)cobalt(II) as catalyst have been studied. The complex [Co(Hdmg)2-(Ph3P)(3,5-DTBCatH)] has been isolated from the reaction mixture and characterized by X-ray diffraction (monoclinic, P21/c, a = 16.498(1) Å, b = 9.254(1) Å, c = 26.038(2) Å, β = 103.59(1)°, V = 3864.0(4) Å3, Dc = 1.33 g cm-3, Z = 4, μ(Cu Kα) = 44.4 cm-1, R = 0.0480). It contains a unidentate 3,5-di-tert-butylcatecholato-(1-) ligand. Upon dissolution and warming in benzene under N2, homolytic Co-O bond cleavage produces cobaloxime(II) and the free 3,5-di-tert-butylsemiquinonato(1-) anion radical, as demonstrated by ESR spectroscopy. In O2-containing solution, the complex restarts the catalytic reaction, during which the [CoIII(Hdmg)2(Ph3P)(3,5-DTBSQ•)] species can also be detected by ESR. The observed behavior is rationalized by a mechanism incorporating the intermediates identified.

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