Synthesis, Characterization, and Reactivity of Functionalized Trinuclear Iron-Sulfur Clusters - A New Class of Bioinspired Hydrogenase Models.

The air- and moisture-stable iron-sulfur carbonyl clusters FeS(CO)(dppm) () and FeS(CO)(dppf) () carrying the bisphosphine ligands bis(diphenylphosphanyl)methane (dppm) and 1,1'-bis(diphenylphosphanyl)ferrocene (dppf) were prepared and fully characterized. Two alternative synthetic routes based on different thionation reactions of triiron dodecacarbonyl were tested. The molecular structures of the methylene-bridged compound and the ferrocene-functionalized derivative were determined by single-crystal X-ray diffraction. The catalytic reactivity of the trinuclear iron-sulfur cluster core for proton reduction in solution at low overpotential was demonstrated. These deeply colored bisphosphine-bridged sulfur-capped iron carbonyl systems are discussed as promising candidates for the development of new bioinspired model compounds of iron-based hydrogenases.