Synthesis, structural characterization and electrochemical studies of [Fe2(μ-L)(CO)6] and [Fe2(μ-L)(CO)5(PPh3)] (L = pyrazine-2,3-dithiolate, quinoxaline-2,3-dithiolate and pyrido[2,3-b]pyrazine-2,3-dithiolate): Towards modeling the active site of [FeFe]–Hydrogenase

Synthesis and structural characterization of iron–sulfur complexes with hydrophilic nitrogen–phosphorus ligands

“…These observations indicate that the higher electron density of the P-coordinated Fe atom leads to stronger electron back-donation from Fe to the CO ligands in the PFe(CO) 2 moiety relative to that in the Fe(CO) 3 moiety [38,39].…”

Synthesis, spectroscopic characterization, and crystal structures of diiron pentacarbonyl complexes with monosubstituted tris(3-chlorophenyl)phosphine or cyclohexyldiphenylphosphine ligands

“…The [15], but shorter than those found in natural enzymes (2.55-2.62 Å ) [2,3] and other diiron complexes [25][26][27][28]. The average Fe-C bond distances of the substituted Fe (1.768 Å for 2 and 1.764 Å for 3) are slightly shorter than those of the unsubstituted Fe (1.796 Å for 2 and 1.781 Å for 3) due to the monophosphine having stronger electron-donating properties than CO [29,30].…”

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

“…The oxidation process may be assigned as 2 to 2 1+ [6,38]. As could be seen from figure 11, using HOAc (pK a ≈ 22.3, in CH 3 CN; E°(vs Fc + /Fc), −1.46 V) as a proton source [41][42][43], the second reduction peak of 2 exhibits catalytic behavior with an overpotential of −0.44 V; the reduction current increases and the position of this peak shifts to a more negative potential with increasing concentration of acetic acid added [44][45][46][47]; the formed H 2 was confirmed by GC. For 5, the reduction process may be designated as 5 to 5 1− .…”

“…The oxidation process in CH 2 Cl 2 may be assigned as 5 to 5 1+ [6,38]. As shown in figure 12, the reduction peak of 5 shows catalytic behavior; with increasing amount of acetic acid, the reduction current increases [44][45][46][47]. According to a criterion of CE (catalytic efficiency = (i cat /i d )/(C HA /C cat ), where i cat is the catalytic current, i d is the current for reduction of the catalyst in the absence of acid, C HA is the acid concentration, and C cat is the catalyst concentration) proposed by Lichtenberger et al, CE is 0.99 and 0.62 for 2 and 5 (0.36 in MeCN), respectively [6].…”