Stuttgart 2012 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 13: Poster 1: Cold Molecules, Femtosecond Spectroscopy, Molecular Dynamics
MO 13.21: Poster
Dienstag, 13. März 2012, 16:30–19:00, Poster.IV
Photoinduced Processes in a Low-Spin Cobalt(II) Semiquinonate Complex — •Fabian Rupp1, Katharina Chevalier1, Matthias M.N. Wolf1, Michele Graf2, Harald Kelm2, Hans-Jörg Krüger2, and Rolf Diller1 — 1Dept. of Physics, Univ. Kaiserslautern — 2Dept. of Chemistry, Univ. Kaiserslautern, 67663 Kaiserslautern, Germany
Metal complexes undergoing valence tautomerism and spin-crossover by external stimuli may be utilized as novel molecular switches [1]. Here we study ultrafast photoinduced processes in the first cobalt(II) semiquinonate complex, that displays spin-crossover properties rather than valence tautomerism [2], by means of femtosecond time-resolved pump-probe-spectroscopy in solution. After photoexcitation of [Co(L-N4tBu2)(dbsq)](B(p-C6H4Cl)4) we probe in the visible/near-infrared (IR) and mid-IR range for dynamical and structural information on the transient species [3]. The observed kinetics support the parallel formation of two cobalt(III) catecholate species with different spin multiplicity that replenish the ground state on a picosecond time scale. The model will be advanced by quantum chemical calculations and further time-resolved as well as steady-state studies of similar complexes that may allow to indentify vibrational marker bands for the assignment of possible redox- and spin-states.
[1] J.-F. Letard et al., Top. Curr. Chem. 235, 221 (2004)
[2] M. Graf et al., Angew. Chem., Int. Ed. 49, 950 (2010)
[3] M.M.N. Wolf et al., Phys. Chem. Chem. Phys. 10, 4264 (2008)