| Abstrakt: |
On the basis of preparation of the known complex [Fe2μSCH22SCO6] A by a new method involving condensation of [μLiS2Fe2CO6] with excess SCH2Br2, twelve new diiron thiadithiolates as mimics of the [FeFe]hydrogenase active site have been synthesized by substitution of the CO ligand and coordination at the central S atom of complex Awith appropriate reagents. Treatment of Awith 1 equiv. of the monodentate ligands PPh3and [η5C5H5η5Ph2PC5H4Fe] in the presence of Me3NO and with 1 equiv. tBuNC and cyclohexyl isocyanide gave the single [2Fe3S]clustercontaining monosubstituted complexes [Fe2μSCH22SCO5L1] 1, L1= PPh3; 2, L1= η5C5H5η5Ph2PC5H4Fe; 3, L1= tBuNC; 4, L1= C6H11NC, whereas the double [2Fe3S]clustercontaining disubstituted complexes [Fe2μSCH22SCO52L2] [5, L2= 4,4′Ph2P2C6H42; 6, L2= transPh2PCH=CHPPh2; 7, L2= 1,4CN2C6H4; 8, L2= η5Ph2PC5H42Fe; 9, L2= η5Ph2PC5H42Ru] were produced by reaction of Awith 0.5 equiv. of the corresponding bidentate ligands in the presence of Me3NO. In addition, the single [2Fe3S]clustercontaining complexes in which the central S atom is coordinated, [Fe2μSCH22SCO6η5MeC5H4CO2FeBF4] 10, [Fe2μSCH22SCO6CrCO5] 11, and [Fe2μSCH22SCO6WCO5] 12, could be obtained by reaction of complex Awith the in situ prepared [η5MeC5H4CO2FeBF4], [CrCO5thf], and [WCO5thf], respectively. While complex 3was found to be able to reduce the proton of the weak acid Et3NHCl to give H2, the Xray crystallographic study confirmed that i each P atom of the phosphane ligands in 1and 8occupies an apical position at the Fe atoms, ii the isocyanide ligand in 3lies in a basal position of the Fe atom, and iii the η5MeC5H4CO2Fe, CrCO5, and WCO5units in 10–12are linked to the central S atom of complex Aby an equatorial bond from the two fused sixmembered rings of their [2Fe3S]cluster cores. |
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