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)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.
authors.affiliation: Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, 2A&2B Raja S. C. Mullick Road, Jadavpur, Kolkata-700032, India. ictkp@iacs.res.in.
authors.forename: Triloke Ranjan
authors.initials: TR
authors.lastname: Lakshman
authors.forename: Sayanti
authors.initials: S
authors.lastname: Chatterjee
authors.forename: Biswarup
authors.initials: B
authors.lastname: Chakraborty
authors.forename: Tapan Kanti
authors.initials: TK
authors.lastname: Paine