Responses of the Fe(CN)₂(CO) Unit to Electronic Changes as Related to Its Role in [NiFe]Hydrogenase

Abstract

The observation of nearly identical infrared spectra in the diatomic (2000 cm -1 ) region of oxidized forms of [NiFe]hydrogenases, as isolated from

Overexpression, Isolation, and Spectroscopic Characterization of the Bidirectional [NiFe] Hydrogenase from Synechocystis sp. PCC 6803

“…This effect is not unusual for redox transitions in standard [NiFe] hydrogenases (see below), as well as for CN Ϫ /CO containing model compounds, and could be explained by a decrease of hydrogen bonding strength between neighboring amino acids and the cyanide ligands (e.g. due to a deprotonation) (21,63).…”

The Cofactor of the Iron–Sulfur Cluster Free Hydrogenase Hmd: Structure of the Light‐Inactivation Product

“…We also do not want to exclude a complexation of iron to the pyridone moiety through p binding, such as in cyclopentadienyl-Fe II -carbonyl complexes [20] or in butadiene-Fe 0 -carbonyl complexes, [21,22] since there is evidence for the presence of two CO molecules bound to the iron center in the active Hmd cofactor. It is interesting to note that CO is also a ligand to the iron center in [NiFe]-and [FeFe]-hydrogenases.…”

Synthesis and Structural Characterization of Potassium Salts of Phosphane‐Substituted (Cyclopentadienyl)iron Dicyanides, and Their Use as Bridging Ligands for Copper(I) Phosphane Derivatives

“…KCpFe(CN) 2 (CO) was prepared by applying published procedures. [13,18] Unless otherwise stated, all photolysis reactions were performed using a mercury-arc 450-W UV immersion lamp purchased from Hanovia. The 200-mL water-cooled photolysis vessel was purchased from Ace Glass.…”

“…Specifically, the ironϪcarbon(cyanide) distances in compounds 1, 4, and 6 are shorter than those seen in KCpFe(CN) 2 CO, where an average FeϪCN distance of 1.911(8) Å was observed. [13,14] This subtle yet statistically relevant bond-length change is the result of replacing the good π-acceptor, CO, with a good donor ligand, phosphane. Concomitantly, the increase in bond order to the FeϪCN bond causes a decrease in the CϪN triple-bond character, where the C(6A)ϪN(1A) bond lengths in compounds 1, 4, and 6 are all longer than that determined in the CO analog [1.143(10) Å ].…”