The mimicking of hydrogenases active sites with a novel view on iron tetracyanide chemistry.

摘要

Hydrogen production at hydrogenase active sites drives the search for mimic complexes. We have succeeded in reproducing iron sites as found in [Fe-Fe], [Ni-Fe] and FeS Cluster free hydrogenases where iron has biologically unusual carbonyl and cyanide ligands.;Understanding the chemistry of [Fe(CO)x(CN)y] prompt studies about [Fe-CN] ligations, with the focal compound Prussian blue (synthesized in 1704). Until very recently the chemistry on Fe-CN was thought to produce only [Fe(CN)6]2- or [Fe(CN)5L]. Just two compounds with [Fe(CN)4L2] moieties were known. [Fe(CN)4] A units can be used to create macro arrays as the bridging ability of CN- is known. At this new chemistry cis- and trans-[FeII(CN)4(DMSO) 2]2- and derivatives are synthesized and studied, as the [(Imidazole)FeII(CN)4(CO)]2- that stands as a prebiotic model of the CO transcription cofactor, CooA.;The hydrogenase mimicking synthetic strategy is based on [(PS2')Fe II(CO)3]. It loses carbonyls producing dimers, whose cyanation results in [(PS2')2FeIIFeII(CO) 2(CN)]1-. This Fe-Fe bimetallic complex has bridging thiolates and Fe-CN, Fe-CO bonds.;[FeIIFeII(PS2')2(CN)(CO) 2]1- is a structurally mimic of the H-cluster in [Fe-Fe] hydrogenases. Its electrochemical and spectroscopic properties allow assessments on how the enzyme is able to produce hydrogen. A redox derivative [Fe IIFeIII(PS2')2(CN)(CO)2] is a rare mixed valence compound with thiolate bridges and CO, CN- ligands. The shortened Fe-Fe distance (2.73 A), IR and UV data reveal a high delocalization of the single electron on both Fe-Fe, classifying as a Type II/III mixed valence compound.;Turning the ligand PS2' into a NS2' analog, renders the carbonyl dimer [FeIFeI(NS2')(CO)5] with the connectivity displayed by the H cluster of Fe-Fe Hydrogenases.