Heidelberg 2015 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 12: Photochemistry and Catalysis

MO 12.1: Hauptvortrag

Mittwoch, 25. März 2015, 11:00–11:30, PH/HS1

Generating high-valent iron with light. Photochemical dynamics — •Peter Vöhringer — Institute for Physical and Theoretical Chemistry, University of Bonn, Wegelerstrasse 12, 53115 Bonn, Germany

The most abundant oxidation states of iron are the ferrous and ferric states, +II and +III, respectively. High-valent iron compounds contain Fe centers at the extraordinary oxidation states, +IV, +V, and +VI. Such species are of paramount importance for the catalysis of a number of biochemically or technologically relevant molecular ransformations. Particularly reactive are high-valent iron species that feature a terminal iron-nitrogen bond, so called nitridoiron compounds, and in which the metal is embedded in a fourfold-symmetrical coordination geometry like in heme proteins. Their isolation has not been accomplished to date, but very few non-heme model systems have been prepared by photochemical means and cryo-trapped in low-temperature solid matrices. Very recently, we have been able to temporally trap such elusive octahedral nitridoiron species even in room temperature liquid solution, i.e. under biochemically and technologically relevant conditions, and to even allow for a preliminary study of their reactivity. To this end, we conducted various time-resolved infrared spectroscopies in combination with laser flash photolysis on time scales ranging from a few seconds all the way down to a few hundered femtseconds. We will review our current state of understanding of the molecular-level mechanisms that are involved in the photochemical route to high-valent iron species as seen through these time-resolved IR methods.