[FeFe] hydrogenase active site modeling: a key intermediate bearing a thiolate proton and Fe hydride

Abstract

The first di-protonated [FeFe] hydrogenase model relevant to key intermediates in catalytic hydrogen production is reported. The complex bearing the S-proton and Fe-hydride is structurally and spectroscopically characterized as well as studied by DFT calculations. The results show that the thiolate sulfur can accept protons during the catalytic routes.

Catalytic Hydrogen Evolution by Fe(II) Carbonyls Featuring a Dithiolate and a Chelating Phosphine

“…Density functional theory (DFT) calculations were carried out using the Becke gradient-corrected exchange functional and Lee−Yang−Parr correlation functional with three parameters (B3LYP) and the 6-31G* basis set. 59,[61][62][63][64][65][66][67][68][69] This level of theory has been found to yield reliable geometries and vibrational frequencies for a number of first-row transition metal systems. [70][71][72][73][74] Nonetheless, in light of recent studies indicating the improved performance of the BP86 and TPSS functionals in describing transition metal containing systems, the geometries and energies of 2 were also calculated using these functionals and the larger TZVPP basis sets.…”

A Reversible Proton Relay Process Mediated by Hydrogen‐Bonding Interactions in [FeFe]Hydrogenase Modeling

“…[12] The most thermodynamically favored product throughout the proton-transfer pathway is 1 mH.I mportantly,a tl ow temperature, the hydrogen-bonding species and transition state (1SHNMe 2 Ph, 1SHNMe 2 Ph in and TS 1 )a re more stable, while the free energyo ft he rest remains almostu nchanged. Thep K a of 1SHNMe 2 Ph is about 3.2 pK a units more basic at 183 Kt han that at 298 K. The hydrogen-bonding pair turns out to be the thermodynamically favored species (DG(1SHNMe 2 Ph)a t1 83 K = À3.74 kcal mol…”

“…[12] The in-situ FTIR measurements ( Figure 1a and S1 in the Supporting Information) reveal the decay of 1 mH,w hich t distance of 3.130(4) i ss horter than the sum of van der Waals radii( 3.35 ). [16] Rauchfuss [9] and Ta larmin et al [7] have reportedt hat model complexes possessing N-protonation are able to form hydrogen-bond interactions with conjugate bases of acids, whereas this work provides ad ifferent perspecScheme2.The interconversionb etween 1SHNMe 2 Ph (left) and 1 mH (right).…”

“…. [12,13] The resultant terminal sulfur (S t )i so bservedt ob ear enhanced electron density,a nd is proposed to be ap otential site for both protonation andp roton relayt ot he Fe center.M oreover,c omplexes containing protonated thiolate sulfurh aveb een envisaged to be importanti ntermediates during the catalytic processes. [13, 14] Twop rotonated products,t he initial Fe-hydride species and the subsequent Fe-hydride-S-protonated species, are formed Scheme1.Putative proton-transfer pathway in C. pasteurianum [FeFe]hydrogenase (PDB ID:3C8Y).…”

Syntheses, crystal structures, and electrochemical studies of diiron complexes from the reactions of [Et3NH][(μ-RS) Fe2(CO)6(μ-CO)] with isothiocyanates

“…Platinum is an excellent catalyst for proton reduction and hydrogen oxidation, but its scarcity and high cost limit widespread use. These considerations have led to the development of molecular catalysts that employ earth-abundant metals [7][8][9][10][11][12]. Synthetic complexes of nickel, cobalt, iron, and molybdenum have been developed as electrocatalysts for the production of hydrogen [13,14].…”