Reactions Starting from Diiron Propanedithiolate [(μ-SCH2)2CH(OH)]Fe2(CO)6 Leading to Malonyl-, PPh3-, and [60]Fullerene-Containing Compounds Relevant to the Active Site of FeFe-Hydrogenases

As the active site models of FeFe-hydrognases, a series of new diiron propanedithiolate compounds (1-7) have been synthesized starting from [(mu-SCH2)(2)CH(OH)]Fe-2(CO)(6) (A). Treatment of A with ethyl malonyl chloride or malonyl dichloride in the presence of pyridine gave the malonyl-containing compounds [(mu-SCH2)(2)CHO2CCH2CO2Et]Fe-2(CO)(6) (1) and [Fe-2(CO)(6)(mu-SCH2)(2)CHO2C](2)CH2 (2) in 64% and 55% yields, respectively. While A reacted with PPh3 in the presence of Me3NO to give the PPh3-substituted compound [(mu(-SCH2)(2)CH(OH)]Fe-2(CO)(5)(PPh3) (3) in 91% yield reaction of 3 with malonyl dichloride in the presence of pyridine produced the malonyl-containing compound [Fe-2(CO)(5)(PPh3)(mu-SCH2)(2)CHO2C](2)CH2 (4) in 67% yield. More interestingly, compounds 1, 2, and 4 could react With C-60 in the presence of CBr4 and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) via Bingel-Hirsch reaction to afford the [60]fullerene compounds [(mu-SCH2)(2)CHO2CC(C-60)CO2Et]Fe-2-(CO)(6) (5), [Fe-2(CO)(6)(mu-SCH2)(2)CHO2C](2)C(C-60) (6), and [Fe-2-(CO)(5)(PPh3)(mu-SCH2)(2)CHO2C](2)C(C-60) (7) in 36-39% yields. While new compounds 1-7 were characterized by elemental analysis and various spectroscopic methods, 1-4 were further characterized by X-ray crystallography, and the photoinduced H-2 evolution catalyzed by 5 was preliminarily investigated.