Phase and redox shifted four iron/four sulfur clusters: fluorous analogs of metalloenzyme cofactors

摘要: Reactions of (1) [Q]2[Fe4S4(SC(CH3)3)4] and the fluorous thiols HS(CH2)nRf8 (n = 2, 3; Rf8 (CF2)7CF3)), or (2) [Na]2[Fe4S4(S(CH2)nRf8)4] 3) [PhCH2P((CH2)3Rf6)3][Br] [PPN][Cl] (PPN Ph3PNPPh3), give title compounds [Q]2[Fe4S4(S(CH2)nRf8)4], comprised a dianion in some cases cations, with Q/n Ph4P/2 (4, 67%), Ph4P/3 (5, Me4N/3 (69%), Ph3P(CH2)2Rf6/2 (73%) PhCH2P((CH2)3Rf6)3/2 (14, 39%), PhCH2P((CH2)3Rf6)3/3 (15, 63%), PPN/2 (36%). The educt [Ph3P(CH2)2Rf6]2[Fe4S4(SC(CH3)3)4] is turn prepared from FeCl3, HSC(CH3)3/CH3ONa, [Ph3P(CH2)2Rf6][I], educts [Na]2[Fe4S4(SC(CH3)3)4] HS(CH2)nRf8. SCH21H 13C NMR signals these paramagnetic salts appear 8.7–10.3 32.3–34.9 ppm downfield those corresponding thiols, but chemical shifts other are nearly normal. UV-visible spectra show bands similar to non-fluorous analogs (290–298 nm 406–415 nm; e 25 700 19 200 M−1 cm−1 for 5). singly soluble organic solvents moderate polarity, not solvents. doubly 14, 15 all assayed, partition coefficients >99.65 : <0.35 (CF3C6F11/toluene) 93.2–93.1 : 6.9–6.8 (FC-72/THF). Cyclic voltammograms carried out using platinum working microelectrode that 4 0.08 V thermodynamically easier reduce than 5.