Fe2(μ-S2C3H6)(CO)6 is a model compound found to mimic the active site structure of the [FeFe]-hydrogenases. To observe the time-dependent behavior of this molecule, ultrafast ultraviolet (UV) or visible excitation with infrared (IR) probe measurements of the carbonyl-stretching region were performed with pump wavelengths of 355 nm and 532 nm. The time delay between pump and probe pulses ranged from -67 ps to 750 ps. The time-dependent photodynamics of Fe2(SC3H6S)(CO)6 was found to depend on the pump laser frequency. UV-excitation produces two competing photolytic mechanisms: CO-loss and cleavage of the Fe-Fe bond. Visible excitation also results in both photoproducts, but with a much higher proportion of the broken Fe-Fe bond intermediate. This is in contrast to trends for a similar metal carbonyl, [CpFe(CO)2]2 (Cp = cyclopentadienyl), which only undergoes breaking of the Fe-Fe bond upon excitation with visible photons.
Journal of Physical Chemistry Letters
hydrogenase, iron carbonyl, time-resolved vibrational spectroscopy, ultrafast infrared, pump-probe spectroscopy, photolytic cleavage.