Sulfide coupling reactions in the synthesis of new iron-sulfur and iron-molybdenum-sulfur complexes.
Challen, Paul Richard
1990
Abstract
The synthesis and structural characterization of the single bridged double cube ($\rm (Fe\sb4S\sb4Cl\sb3)\sb2S$) $\sp{4-}$ prepared by coupling of ($\rm Fe\sb4S\sb4Cl\sb4$) $\sp{2-}$ with sulfide ion is described. The double cube has been isolated as the $\rm (Et\sb4N)\sp{+}$ (I), $\rm (n$-$\rm But\sb4N)\sp{+}$ (II) and mixed-cation $\rm (n$-$\rm But\sb4N)\sp{+}$/(PPh$\sb4)\sp{+}$ (III) salts. The crystal structure of (III) is described in detail. The reaction of (III) with azide to give the terminally coordinated mono-azide derivative ($\rm (Fe\sb4S\sb4Cl\sb3)(Fe\sb4S\sb4Cl\sb2N\sb3$)S) $\sp{4-}$ as the $\rm (n$-$\rm But\sb4N)\sp{+}$ (IV) and $\rm (n$-$\rm But\sb4N)\sp+$/(PPh$\sb4)\sp{+}$ (V) salts is described. (V) is X-ray isomorphous and isostructural with (III). Spectroscopic properties described for (III) and (V) include uv/vis, mid and far i.r., electrochemistry, Mossbauer and EPR. The sulfide coupling of $\rm (Et\sb4N)\sb2$ ($\rm MoFe\sb3$S$\sb4$Cl$\sb3$(Cl$\sb4$cat)(CH$\sb3$CN)) to give the double bridged double cubes (Et$\sb4$N)$\sb6\{$ ($\rm MoFe\sb3S\sb4Cl\sb2(Cl\sb4$cat)) $\sb2$(S)$\sb2\}$ (VI) and (Et$\sb4$N)$\sb5\{$ ($\rm MoFe\sb3S\sb4Cl\sb2(Cl\sb4$cat)) $\sb2$(S)(OH)$\}$ (VII) is described together with the crystal structures of (VI) and (VII). The incorporation into the double cubes of the nitrogenase-related species CN$\sp-$, NH$\sb2$NH$\sb2$ and $\rm N\sb3\sp-$ as bridging ligands to give the clusters (Et$\sb4$N)$\sb5\{$ ($\rm MoFe\sb3S\sb4Cl\sb2(Cl\sb4$cat)) $\sb2$(S)(CN)$\}$ (VIII), (Et$\sb4$N)$\sb4\{$ ($\rm MoFe\sb3S\sb4Cl\sb2(Cl\sb4$cat)) $\sb2$(S)(NH$\sb2$NH$\sb2)\}$ (IX) and (Et$\sb4$N)$\sb5\{$ ($\rm MoFe\sb3S\sb4Cl\sb2(Cl\sb4$cat)) $\sb2$(S)(N$\sb3)\}$ (X) is described, together with uv/vis, mid and far i.r., electrochemistry, Mossbauer and EPR spectroscopy of (VI), (VII), (VIII), (IX) and (X). The synthesis of the mixed double cube $\{$ ($\rm Fe\sb4S\sb4Cl\sb2$) ($\mu\sb2$-S)$\sb2$ ($\rm MoFe\sb3S\sb4Cl\sb2(Cl\sb4$cat)) $\}\sp{5-}$ (XI) by sulfide coupling of ($\rm Fe\sb4S\sb4Cl\sb4$) $\sp{2-}$ with ($\rm MoFe\sb3S\sb4Cl\sb3(Cl\sb4cat)(CH\sb3$CN)) $\sp{2-}$ is described together with uv/vis, far i.r., electrochemistry and EPR spectroscopy of (XI). The relevance of the above clusters to the nitrogenase enzyme system is discussed. NMR evidence is presented for the coupling of ($\rm Fe\sb4S\sb4(SPh)\sb4$) $\sp{2-}$ with sulfide to give ($\rm (Fe\sb4S\sb4(SPh)\sb3$)2S) $\sp{4-}$ (XII). The reaction of ($\rm Fe\sb4S\sb4(SEt)\sb4$) $\sp{2-}$ with sulfide to form the new cluster type ($\rm Fe\sb8S\sb{12}(SEt)\sb2$) $\sp{6-}$ is described. Premilinary crystal structure data on $\rm (Et\sb4N)\sb6$ ($\rm Fe\sb8S\sb{12}(Set)\sb2$) (XIII) is presented together with uv/vis, electrochemistry, Mossbauer and EPR spectroscopic data.Subjects
Complexes Coupling Iron Molybdenum New Reactions Sulfide Sulfur Synthesis
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