Electron spin resonance and Mössbauer evidence for the trianion [Fe2S2{(SCH2)2C6H4-o}2]3–

Abstract

Dimethylformamide solutions of [NEt₄]₂[Fe₂S₂{(SCH₂)₂C₆H₄-o}₂] may be reduced at –50 °C using monosodium acenaphthylenide, to give paramagnetic solutions believed to contain the trianion [Fe₂S₂{(SCH₂)₂C₆H₄-o}₂]^3– in 60–80% yield. The evidence for this is as follows: the e.s.r. spectrum of a sample enriched in ⁵⁷Fe was well simulated on this assumption; the g values of 2.007, 1.940, and 1.922, the ⁵⁷Fe hyperfine splittings of 1.52 and 1.35 mT for the two iron atoms, and the variation in linewidth with temperature are quite compatible with published data for reduced two-iron ferredoxins; the Mössbauer spectrum gives clear evidence of antiferromagnetically coupled components of a paramagnetic species closely resembling those found in reduced two-iron ferredoxins. A comparison is made between these results and those of other workers.