Synthesis and Characterization of [FeFe]‐Hydrogenase Models with Bridging Moieties Containing (S, Se) and (S, Te)

Abstract

Se{ 1 H} NMR, IR, and photoelectron spectroscopic techniques along with structure determination with single-crystal X-ray diffraction, electrochemical measurements, and DFT calculations. He I photoelectron spectra and DFT computa-

Diiron Dichalcogenolato (Se and Te) Complexes: Models for the Active Site of [FeFe] Hydrogenase

“…The computational methodology utilized by Weigand and co-workers to investigate these catalysts (12, 13, 23-27) has previously been shown to give good quantitative agreement with the structures, CO stretching frequencies (νCO), oxidation and reduction potentials, bond energies, and pK a values of a variety of catalysts inspired by [FeFe] hydrogenase active sites. [56,59,60,[101][102][103] The optimized geometries and computed νCO values agree very well with the experimental values, suggesting that the computations are able to yield sufficiently reasonable electron distributions and energies for catalysts 12, 14, and 23-27.…”

“…The mixed (S, Se) Fe 2 (μ-SC 3 H 6 Se)(CO) 6 (26) and (S, Te) Fe 2 (μ-SC 3 H 6 Te)-(CO) 6 (27) complexes were prepared by reaction of 1,2-thiaselenolane and 1,2-thiatellurolane with Fe 3 (CO) 12 (Scheme 10). [60] Cyclic voltammetry revealed no influence of the heavier chalcogens to the one-electron oxidation. In contrast, significant shifts of the reduction potentials to more positive values were observed [-1.652 V (12) Ͼ -1.618 V (26) Ͼ -1.585 V (27)].…”

“…In contrast, significant shifts of the reduction potentials to more positive values were observed [-1.652 V (12) Ͼ -1.618 V (26) Ͼ -1.585 V (27)]. [60] It is remarkable that this trend was also …”

“…Recently, we and others paid attention to model complexes containing the heavier chalcogens such as Se or Te instead of sulfur. [52][53][54][55][56][57][58][59][60] Herein we highlight recent work on this topic, in order to give the reader an overview of the consequences of substituting selenium or tellurium in lieu of sulfur in dichalcogenolato [FeFe] hydrogenase model compounds.…”

“…[56,[58][59][60] These active site catalysts typically exhibit extensive overlap of six Fe 3d orbitals and range up to about 9 eV with a weak shoulder on the low ionization energy side corresponding to ionization from the HOMO. The HOMO is calculated to be predominantly the Fe-Fe σ bond (vide infra), with an adiabatic ionization (IE A ) energy around 7.5 eV.…”