title: New tetracobalt cluster compounds for electrocatalytic proton reduction: syntheses, structures, and reactivity.
abstract: Reaction of Co2(CO)8 and 1,3-propanedithiol in a 1:1 molar ratio in toluene affords a novel tetracobalt complex, [(μ2-pdt)2(μ3-S)Co4(CO)6] (pdt = -SCH2CH2CH2S-, 1), which possesses some of the structural features of the active site of [FeFe]-hydrogenase. Carbonyl displacement reaction of complex 1 in the presence of mono- or diphosphine ligands leads to the formation of [(μ2-pdt)2(μ3-S)Co4(CO)5(PCy3)] (2) and [(μ2-pdt)2(μ3-S)Co4(CO)4(L)] [L = Ph2PCH=CHPPh2, 3; Ph2PCH2N(Ph)CH2PPh2, 4; Ph2PCH2N(iPr)CH2PPh2, 5]. Complexes 1-5 have been fully characterized by spectroscopy and single-crystal X-ray diffraction studies. Cyclic voltammetry has revealed that complexes 1-5 show a reversible first reduction wave and are active for electrocatalytic proton reduction in the presence of CF3COOH. Protonation reactions have been monitored by (31)P and (1)H NMR and infrared spectroscopies, which revealed the formation of different protonated species. The mono-reduced species of 1-5 have been spectroscopically characterized by EPR and spectro-electro-infrared techniques.
authors: Homogeneous & Supramolecular Catalysis van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam (The Netherlands), Fax: (+31) 20-525-5265.
authors: Ping
authors: P
authors: Li
authors: Riccardo
authors: R
authors: Zaffaroni
authors: Bas
authors: B
authors: de Bruin
authors: Joost N H
authors: JN
authors: Reek
keywords: bio-inspired; cluster compounds; electrocatalyst; proton reduction; redox chemistry