Iron-cyanide chemistry, from modeling hydrogenase active sites to developing new iron cyanide chemistry.

摘要

Hydrogenases are enzymes mediators in hydrogen activation either for reduction or oxidation processes. There are three types of hydrogenase enzymes: (1) [Ni-Fe] hydrogenase. (2) [Fe-Fe] hydrogenase. (3) HMD or FeS cluster-free hydrogenases.;The first two are involved in producing hydrogen from H+ and electrons or evolving H2. HMD catalyzes the reduction of N 5,N10-methenyl-5,6,7,8-tetrahydro methanopterin, a hydrogen acceptor, and the reverse process. Hydrogenases possess iron moieties in their active centers; with carbonyl and cyanide ligands what is remarkable for being, so far, a singular case in biological systems.;A series of mimic complexes [(PS2')Fe(CN)x(CO)(3-x)] n (x= 0, 1, 2, 3) have been synthesized from the reaction of (PS2') 2- (bis(5-methyl-2-phenylthiolate) phenylphosphine) with FeCl2 in high yield. These compounds have been structurally characterized; their chemical, spectroscopic and electrochemical properties have been studied. They constitute useful spectroscopic models for the [Fe(CN) x(CO)y] centers in [Ni-Fe] and [Fe-Fe] hydrogenases and the cis-[Fe(CO)2] containing cofactor in Hmd hydrogenases.;Looking for a new synthetic route to achieve new mimics, a set of [Fe II,III(CN)4L2]n- complexes has been synthesized by the single step reaction of Fe(II) with CN-. This compounds have a moderate reactivity and are also useful building blocks to prepare new Prussian blue type materials and as possible stoichiometric or catalytic reagents.;The synthesis of the [Fe(CN)4L2] (L = monodentate ligand) and their applications is a new area in the chemistry of iron-cyanide compounds, the oldest known field of coordination chemistry. [FeII (CN)6]4-, the parent of iron-cyanide complexes, which has been known for 250 years is characterized by its inert nature such that it is not poisonous. [Et4N]4[FeII(CN) 6] is the first well characterized salt which is soluble in organic solvents. It is a powerful reducing agent and shows dramatic increases in the rate of substitution reactions of its CN- ligands.