Phosphane‐ and Phosphite‐Substituted Diiron Diselenolato Complexes as Models for [FeFe]‐Hydrogenases

Abstract

Keywords: Iron / Hydrogenases / Substitution / Electrocatalysis / Ligand effects / Enzyme catalysis / SeleniumThe displacement of terminal CO ligands in Fe 2 (µ-Se 2 C 3 H 5 CH 3 )(CO) 6 (1) by triphenylphosphane, trimethyl phosphite, and bis(diphenylphosphanyl)ethane (dppe) ligands is investigated. Treatment of 1 with 1 equiv. of triphenylphosphane afforded Fe 2 (µ-Se 2 C 3 H 5 CH 3 )(CO) 5 (PPh 3 ) (2). The mono-and disubstituted phosphite complexes Fe 2 (µ-Se 2 C 3 H 5 CH 3 )(CO) 5 P(OMe) 3 (3)andFe 2 (µ-Se 2 C 3 H 5 CH 3 )(CO) 4 -[P(OMe) 3 ] 2 (4) were obtained from the reaction of 1 with excess P(OMe) 3 at reflux in toluene. In contrast, the reaction of 1 with 1 equiv. of dppe in the presence of Me 3 NO·2H 2 O gave

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

“…pounds containing dithiolato, diselenolato, [33][34][35][36][37][38] or ditellurolato [33,[39][40][41] bridging ligands have been prepared, characterized, and evaluated for the electrocatalytic production of H 2 from weak acids.…”

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

“…[57] This investigation was followed by the work of Weigand and co-workers, in which a substitution study of the carbonyl groups of compound 14 by PPh 3 or P(OMe) 3 . [58] Moreover, the replacement of carbonyl ligands of 14 by bis(diphenylphosphanyl)ethane (dppe) afforded the chelated diiron complex 21 and the bridged tetrairon complex 22 (Scheme 8). [58] In contrast to the numerous crystallographic data of such compounds, only little is known about substituted [2Fe2Se] complexes.…”

“…[58] Moreover, the replacement of carbonyl ligands of 14 by bis(diphenylphosphanyl)ethane (dppe) afforded the chelated diiron complex 21 and the bridged tetrairon complex 22 (Scheme 8). [58] In contrast to the numerous crystallographic data of such compounds, only little is known about substituted [2Fe2Se] complexes. Solely the electrochemical properties of complex 18 are described in the literature.…”

“…Solely the electrochemical properties of complex 18 are described in the literature. [58] A significant shift of both the oxidation [+0. 35 V (18) [58] Ͻ +0.76 V (14) [56] ] and reduction potential [-2.00 V (18) [58] Ͻ -1.83 V (14) [56] ] was observed.…”

“…[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.…”