Multiple-timescale photoreactivity of a model compound related to the active site of [FeFe]-hydrogenase

Ultraviolet (UV) photolysis of (mu-S(CH2)(3)S)Fe-2(CO)(6) (1), a model compound of the Fe-hydrogenase enzyme system, has been carried out. When ultrafast UV-pump infrared (IR)-probe spectroscopy, steady-state Fourier transform IR spectroscopic methods, and density functional theory simulations are employed, it has been determined that irradiation of I in an alkane solution at 350 nm leads to the formation of two isomers of the 16-electron complex (mu-S(CH2)(3)S)Fe-2(CO)(5) within 50 ps with evidence of a weakly associated solvent adduct complex. 1 is subsequently recovered on timescales covering several minutes. These studies constitute the first attempt to study the photochemistry and reactivity of these enzyme active site models in solution following carbonyl ligand photolysis.