title: Triggering the generation of an iron(IV)-oxo compound and its reactivity toward sulfides by Ru(II) photocatalysis.
abstract: The preparation of [Fe(IV)(O)(MePy2tacn)](2+) (2, MePy2tacn = N-methyl-N,N-bis(2-picolyl)-1,4,7-triazacyclononane) by reaction of [Fe(II)(MePy2tacn)(solvent)](2+) (1) and PhIO in CH3CN and its full characterization are described. This compound can also be prepared photochemically from its iron(II) precursor by irradiation at 447 nm in the presence of catalytic amounts of [Ru(II)(bpy)3](2+) as photosensitizer and a sacrificial electron acceptor (Na2S2O8). Remarkably, the rate of the reaction of the photochemically prepared compound 2 toward sulfides increases 150-fold under irradiation, and 2 is partially regenerated after the sulfide has been consumed; hence, the process can be repeated several times. The origin of this rate enhancement has been established by studying the reaction of chemically generated compound 2 with sulfides under different conditions, which demonstrated that both light and [Ru(II)(bpy)3](2+) are necessary for the observed increase in the reaction rate. A combination of nanosecond time-resolved absorption spectroscopy with laser pulse excitation and other mechanistic studies has led to the conclusion that an electron transfer mechanism is the most plausible explanation for the observed rate enhancement. According to this mechanism, the in-situ-generated [Ru(III)(bpy)3](3+) oxidizes the sulfide to form the corresponding radical cation, which is eventually oxidized by 2 to the corresponding sulfoxide.
authors.affiliation: Grup de Química Bioinorgànica i Supramolecular (QBIS), Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi , E17071 Girona, Catalonia, Spain.
authors.forename: Anna
authors.initials: A
authors.lastname: Company
authors.forename: Gerard
authors.initials: G
authors.lastname: Sabenya
authors.forename: María
authors.initials: M
authors.lastname: González-Béjar
authors.forename: Laura
authors.initials: L
authors.lastname: Gómez
authors.forename: Martin
authors.initials: M
authors.lastname: Clémancey
authors.forename: Geneviève
authors.initials: G
authors.lastname: Blondin
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Jasniewski
authors.forename: Mayank
authors.initials: M
authors.lastname: Puri
authors.forename: Wesley R
authors.initials: WR
authors.lastname: Browne
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Latour
authors.forename: Lawrence
authors.initials: L
authors.lastname: Que
authors.forename: Miquel
authors.initials: M
authors.lastname: Costas
authors.forename: Julia
authors.initials: J
authors.lastname: Pérez-Prieto
authors.forename: Julio
authors.initials: J
authors.lastname: Lloret-Fillol