Substrate-dependent aromatic ring fission of catechol and 2-aminophenol with O2 catalyzed by a nonheme iron complex of a tripodal N4 ligand

Triloke Ranjan Lakshman; Sayanti Chatterjee; Biswarup Chakraborty; Tapan Kanti Paine

doi:10.1039/c5dt04541j

Substrate-dependent aromatic ring fission of catechol and 2-aminophenol with O₂ catalyzed by a nonheme iron complex of a tripodal N₄ ligand

Triloke Ranjan Lakshman, Sayanti Chatterjee, Biswarup Chakraborty, Tapan Kanti Paine

Research output: Contribution to journal › Article › peer-review

12 Scopus citations

Abstract

The catalytic reactivity of an iron(ii) complex [(TPA)Fe^II(CH₃CN)₂]²⁺ (1) (TPA = tris(2-pyridylmethyl)amine) towards oxygenative aromatic C-C bond cleavage of catechol and 2-aminophenol is presented. Complex 1 exhibits catalytic and regioselective C-C bond cleavage of 3,5-di-tert-butylcatechol (H₂DBC) to form intradiol products, whereas it catalyzes extradiol-type C-C bond cleavage of 2-amino-4,6-di-tert-butylphenol (H₂AP). The catalytic reactions are found to be pH-dependent and the complex exhibits maximum turnovers at pH 5 in acetonitrile-phthalate buffer. An iron(iii)-catecholate complex [(TPA)Fe^III(DBC)]⁺ (2) is formed in the ring cleavage of catechol. In the extradiol-type cleavage of H₂AP, an iron(iii)-2-iminobenzosemiquinonate complex [(TPA)Fe^III(ISQ)]²⁺ (3) (ISQ = 4,6-di-tert-butyl-2-iminobenzosemiquinonate radical anion) is observed in the reaction pathway. This work shows the importance of the nature of 'redox non-innocent' substrates in governing the mode of ring fission reactivity.

Original language	English
Pages (from-to)	8835-8844
Number of pages	10
Journal	Dalton Transactions
Volume	45
Issue number	21
DOIs	https://doi.org/10.1039/c5dt04541j
State	Published - 1 Jan 2016
Externally published	Yes

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Inorganic Chemistry

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title = "Substrate-dependent aromatic ring fission of catechol and 2-aminophenol with O2 catalyzed by a nonheme iron complex of a tripodal N4 ligand",

abstract = "The catalytic reactivity of an iron(ii) complex [(TPA)FeII(CH3CN)2]2+ (1) (TPA = tris(2-pyridylmethyl)amine) towards oxygenative aromatic C-C bond cleavage of catechol and 2-aminophenol is presented. Complex 1 exhibits catalytic and regioselective C-C bond cleavage of 3,5-di-tert-butylcatechol (H2DBC) to form intradiol products, whereas it catalyzes extradiol-type C-C bond cleavage of 2-amino-4,6-di-tert-butylphenol (H2AP). The catalytic reactions are found to be pH-dependent and the complex exhibits maximum turnovers at pH 5 in acetonitrile-phthalate buffer. An iron(iii)-catecholate complex [(TPA)FeIII(DBC)]+ (2) is formed in the ring cleavage of catechol. In the extradiol-type cleavage of H2AP, an iron(iii)-2-iminobenzosemiquinonate complex [(TPA)FeIII(ISQ)]2+ (3) (ISQ = 4,6-di-tert-butyl-2-iminobenzosemiquinonate radical anion) is observed in the reaction pathway. This work shows the importance of the nature of 'redox non-innocent' substrates in governing the mode of ring fission reactivity.",

author = "Lakshman, {Triloke Ranjan} and Sayanti Chatterjee and Biswarup Chakraborty and Paine, {Tapan Kanti}",

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T1 - Substrate-dependent aromatic ring fission of catechol and 2-aminophenol with O2 catalyzed by a nonheme iron complex of a tripodal N4 ligand

AU - Lakshman, Triloke Ranjan

AU - Chatterjee, Sayanti

AU - Chakraborty, Biswarup

AU - Paine, Tapan Kanti

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N2 - The catalytic reactivity of an iron(ii) complex [(TPA)FeII(CH3CN)2]2+ (1) (TPA = tris(2-pyridylmethyl)amine) towards oxygenative aromatic C-C bond cleavage of catechol and 2-aminophenol is presented. Complex 1 exhibits catalytic and regioselective C-C bond cleavage of 3,5-di-tert-butylcatechol (H2DBC) to form intradiol products, whereas it catalyzes extradiol-type C-C bond cleavage of 2-amino-4,6-di-tert-butylphenol (H2AP). The catalytic reactions are found to be pH-dependent and the complex exhibits maximum turnovers at pH 5 in acetonitrile-phthalate buffer. An iron(iii)-catecholate complex [(TPA)FeIII(DBC)]+ (2) is formed in the ring cleavage of catechol. In the extradiol-type cleavage of H2AP, an iron(iii)-2-iminobenzosemiquinonate complex [(TPA)FeIII(ISQ)]2+ (3) (ISQ = 4,6-di-tert-butyl-2-iminobenzosemiquinonate radical anion) is observed in the reaction pathway. This work shows the importance of the nature of 'redox non-innocent' substrates in governing the mode of ring fission reactivity.

AB - The catalytic reactivity of an iron(ii) complex [(TPA)FeII(CH3CN)2]2+ (1) (TPA = tris(2-pyridylmethyl)amine) towards oxygenative aromatic C-C bond cleavage of catechol and 2-aminophenol is presented. Complex 1 exhibits catalytic and regioselective C-C bond cleavage of 3,5-di-tert-butylcatechol (H2DBC) to form intradiol products, whereas it catalyzes extradiol-type C-C bond cleavage of 2-amino-4,6-di-tert-butylphenol (H2AP). The catalytic reactions are found to be pH-dependent and the complex exhibits maximum turnovers at pH 5 in acetonitrile-phthalate buffer. An iron(iii)-catecholate complex [(TPA)FeIII(DBC)]+ (2) is formed in the ring cleavage of catechol. In the extradiol-type cleavage of H2AP, an iron(iii)-2-iminobenzosemiquinonate complex [(TPA)FeIII(ISQ)]2+ (3) (ISQ = 4,6-di-tert-butyl-2-iminobenzosemiquinonate radical anion) is observed in the reaction pathway. This work shows the importance of the nature of 'redox non-innocent' substrates in governing the mode of ring fission reactivity.

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Substrate-dependent aromatic ring fission of catechol and 2-aminophenol with O₂ catalyzed by a nonheme iron complex of a tripodal N₄ ligand

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