title: Mechanism of Reduction of Ferric Porphyrins by Sulfide: Identification of a Low Spin FeIII-SH Intermediate.
abstract: The reaction of FeIIIporphyrin complexes bearing distal hydrogen bonding residues with sulfide/hydrosulfide is kinetically monitored to reveal the presence of an intermediate and a kH/kDof 3.0. This intermediate is trapped at low temperatures and investigated with resonance Raman and electron paramagnetic resonance spectroscopy. The results, corroborated by density functional theory calculations, indicate that this species is a six-coordinate low spin hydrosulfide bound ferric porphyrin. The homolytic cleavage of the FeIII-SH bond resulting in the formation of a ferrous porphyrin and hydrosulfide radical (trapped with 5,5-dimethyl-1-pyrrilone-N-oxide) is found to be the overall rate-determining step of the reaction.
authors.affiliation: Department of Inorganic Chemistry, Indian Association for the Cultivation of Science , Kolkata, India 700032.
authors.forename: Kaustuv
authors.initials: K
authors.lastname: Mittra
authors.affiliation: Department of Inorganic Chemistry, Indian Association for the Cultivation of Science , Kolkata, India 700032.
authors.forename: Asmita
authors.initials: A
authors.lastname: Singha
authors.affiliation: Department of Inorganic Chemistry, Indian Association for the Cultivation of Science , Kolkata, India 700032.
authors.forename: Abhishek
authors.identifier: http://orcid.org/0000-0002-9166-3349
authors.initials: A
authors.lastname: Dey