Photodynamics of [FeFe]-Hydrogenase Model Compounds with Bidentate Heterocyclic Ligands


Two asymmetrically structured model compounds for the hydrogen-generating [Fe-Fe]-hydrogenase active site were investigated to determine the ultrafast photodynamics, structural intermediates, and photoproducts compared to more common symmetric di-iron species. The bidentate-ligand-containing compounds studied were Fe2(μ-S2C3H6)(CO)4(bipy), 1, and Fe2(μ-S2C3H6)(CO)4(phen), 2, in dilute room temperature acetonitrile solution and lowerature 2Me-THF matrix isolation using static FTIR difference and time-resolved infrared spectroscopic methods (TRIR). Ultraviolet-visible spectra were also compared to time-dependent density functional theory (TD-DFT) to ascertain the orbital origins of long wavelength electronic absorption features. The spectroscopic evidence supports the conclusions that only a propyl-bridge flip occurs in lowerature matrix, while early time CO ejection leads to the formation of solvated isomeric species on the 25 ps time scale in room temperature solution.

Publication Title

Journal of Physical Chemistry B