Coordination Sphere Flexibility of Active-Site Models for Fe-Only Hydrogenase: Studies in Intra- and Intermolecular Diatomic Ligand Exchange
Citations Over TimeTop 10% of 2001 papers
Abstract
A series of dinuclear complexes, (mu-SRS)Fe(2)(CO)(6) (R = -CH(2)CH(2)-, -CH(2)CH(2)CH(2)-, -CH(2)-C(6)H(4)-CH(2)-; edt, pdt, and o-xyldt, respectively) has been examined for specific characteristics that might relate to structural similarity with the active site of Fe-only hydrogenases. Variable-temperature proton NMR studies display the fluxionality of the iron-dithiocyclohexane unit in (mu-pdt)Fe(2)(CO)(6) while in the (mu-o-xyldt)Fe(2)(CO)(6) compound, the bridge is fixed. Temperature-dependent (13)C NMR spectral studies establish intramolecular CO site exchange localized on discrete Fe(CO)(3) units in all complexes, which is influenced by steric effects of the mu-SRS unit. Kinetic studies of intermolecular CO/CN(-) ligand-exchange reactions establish associative or I(a) mechanisms in sequential steps to form the dicyano dianion, (mu-SRS)[Fe(CO)(2)(CN)](2)(=) with 100% selectivity. Theoretical calculations (DFT) of transition states in the intramolecular site-exchange processes lead to a rationale for the interesting cooperativity in the CN(-)/CO intermolecular ligand-exchange process. The hinge motion of the three light atom S-to-S bridge is related to a possible heterolytic H(2) activation/production process in the enzyme.
Related Papers
- → Quantification of the Steric Properties of 1,8-Naphthyridine-Based Ligands in Dinuclear Complexes(2022)13 cited
- → An estimate of the steric bulk of the trimethyltin group.(1972)17 cited
- → Primary steric effects in five-membered heterocyclic systems(1971)10 cited
- → Steric Effects. II. General Equations. Application to Cis- and Trans−2-Butene(1948)18 cited
- → Quantification of the Steric Properties of 1,8-Naphthyridine Based Ligands in Dinuclear Complexes(2022)