Mainz 2017 – scientific programme
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MO: Fachverband Molekülphysik
MO 13: Probing Vibrations
MO 13.3: Talk
Thursday, March 9, 2017, 11:45–12:00, N 6
The primary photochemical processes upon laser flash photolysis of a puckered ferrocyclobutadiene in liquid solution studied by ultrafast femtosecond mid-infrared spectroscopy — •Boris Wezisla, Jörg Lindner, and Peter Vöhringer — University of Bonn
The primary photoprocesses after laser flash excitation of the novel puckered ferracyclobutadiene, [Fe{κ2-C3(NEt2)3}(CO)3]BF4, are explored using femtosecond time-resolved infrared spectroscopy in conjunction with extensive signal deconvolution and quantum mechanical computations, in an effort to fathom the possibility of utilizing this class of metallacyclobutadienes as efficient alkyne metathesis catalysts.
Signal deconvolution uncovers two short lived key intermediates for the primary substitution of a single CO ligand by an acetonitrile solvent molecule, which we already discovered in a previous study with nanosecond time-resolution [1]. These intermediates are assigned by comparison with DFT calculations to the triplet ground state of the precursor molecule and a formally octahedral, planarized ferracycle with an associated explicit solvent, respectively. By inclusion of the analytical solution of a kinetic model into the global fitting routine, reaction rates for elementary steps in the photochemical relaxation are determined, which explain the origin of the low and excitation wavelenth dependent primary quantum yield of less than 25%.
[1] J. Torres-Alacan, B. Wezisla, M. Straßmann, A. C. Filippou, P. Vöhringer, Chem. Eur. J., 2015, 21, 17184-17190.