933473-70-2Relevant academic research and scientific papers
Binuclear iron-sulfur complexes with bidentate phosphine ligands as active site models of Fe-hydrogenase and their catalytic proton reduction
Gao, Weiming,Ekstrom, Jesper,Liu, Jianhui,Chen, Changneng,Eriksson, Lars,Weng, Linhong,Akermark, Bjorn,Sun, Licheng
, p. 1981 - 1991 (2007)
The displacement of CO in a few simple Fe(I)-Fe(I) hydrogenase model complexes by bisphosphine ligands Ph2P-(CH2) n,-PPh2 [with n = 1 (dppm) or n = 2 (dppe)] is described. The reaction of [{μ-(SCH2)2CH2}Fe 2(CO)6] (1) and [{μ-(SCH2) 2N(CH2CH2CH3)}Fe2(CO) 6] (2) with dppe gave double butterfly complexes [{μ-(SCH 2)2CH2}Fe2(CO)5(Ph 2-PCH2)]2 (3) and [{μ-(SCH2) 2N(CH2CH2CH3)}Fe2(CO) 5(Ph2PCH2 (4), where two Fe2S 2 units are linked by the bisphosphine. In addition, an unexpected byproduct, [{μ-(SCH2)2N(CH2CH 2CH3)}Fe2(CO)5{Ph 2PCH2CH2(Ph2PS)}] (5), was isolated when 2 was used as a substrate, where only one phosphorus atom of dppe is coordinated, while the other has been converted to P=S, presumably by nucleophilic attack on bridging sulfur. By contrast, the reaction of 1 and 2 with dppm under mild conditions gave only complexes [{μ-(SCH 2)2CH2}Fe2(CO)5(Ph 2PCH2-PPh2)] (6) and [{μ-(SCH 2)2N(CH2CH2CH3)}Fe 2(CO)5(Ph2PCH2PPh2)] (8), where one ligand coordinated in a monodentate fashion to one Fe 2S2 unit. Furthermore, under forcing conditions, the complexes [{μ-(SCH2)2CH2}-Fe 2(CO)4{μ-(Ph2P)2CH2}] (7) and [{μ-(SCH2)2N(CH2CH 2CH3)}Fe2(CO)4{μ-(PH 2P)2CH2}] (9) were formed, where the phosphine acts as a bidentate ligand, binding to both the iron atoms in the same molecular unit. Electrochemical studies show that the complexes 3, 4, and 9 catalyze the reduction of protons to molecular hydrogen, with 4 electrolyzed already at -1.40 V versus Ag/AgNO3 (-1.0 V vs NHE).
