[Fe-Fe] Hydrogenase Models: Iron(I)-Carbonyl Clusters Coupled To Alpha- and Para-Toluenethiolate Ligands
Two linkage isomers composing of diironhexacarbonyl clusters coupled to α and p-toluenethiolate ligands have been usefully prepared in moderate yields. The composition of both compounds, [(μ2-(p-toluenethiolato))2Fe2(CO)6] (1) and [(μ2-(α-toluenethiolato))2Fe2(CO)6] (2), have been determined by elemental analysis and NMR spectroscopy. A tetrairondodecacarbonyl complex, [μ4-S(μ2-(α-toluenethiolato)Fe2(CO)6)2] (3), was isolated from the reaction mixture of 2. The molecular structures of 2 and 3 determined by X-ray diffraction are discussed. An exploration of the influence of the α- and p-toluenethiolate ligands on the electronic and electrochemical properties of the iron-carbonyl units have been accomplished using infrared spectroscopy, UV–Vis spectroscopy and cyclic voltammetry. In the presence of acetic acid, compounds 1, 2 and 3 catalyze the electrochemical generation of molecular hydrogen. The proton reduction overpotentials for compounds 1 and 2 were determined to be 0.76 V and 0.85 V versus Fc/Fc+ respectively in acetonitrile as solvent. Comparatively, compound 1 produces hydrogen at an overpotential 90 mV lower than compound 2.
Haley, Adrian L.; Broadbent, Lauren N.; McDaniel, Lindsey S.; Heckman, Skye T.; Hinkle, Carlee H.; Gerasimchuk, Nikolay N.; Hershberger, John C.; and Mebi, Charles A., "[Fe-Fe] Hydrogenase Models: Iron(I)-Carbonyl Clusters Coupled To Alpha- and Para-Toluenethiolate Ligands" (2016). Faculty Publications - Physical Sciences. 31.