[Fe-Fe] hydrogenase models: Iron(I)-carbonyl clusters coupled to alpha- and para-toluenethiolate ligands

Two linkage isomers, [(μ2-(p-toluenethiolato))2Fe2(CO)6] (1) and [(μ2-(α-toluenethiolato))2Fe2(CO)6] (2) have been prepared in moderate yields. The composition and structure of the compounds were ascertained by elemental analysis, NMR spectroscopy and X-ray diffraction. Comparatively, compound 1 electrochemical reduces proton to hydrogen at an overpotential 90 mV lower than compound 2.51