G. Delbert Friesen

Syntheses and characterization of ammonium and tetraalkylammonium thiomolybdates and thiotungstates

Abstract Improved methods for the preparation of [NH 4 ] 2 [MO 2 S 2 ] and [NH 4 ] 2 [MS 4 ] are summarized and new syntheses of [NH 4 ] 2 [MOS 3 ] are reported (M = Mo, W). The facile conversion of the [NH 4 ] + salts to [Et 4 N] + salts via reaction with aqueous [Et 4 N]OH is also described. Infrared and electronic spectral data for the thiometallates are summarized as an aid to future characterization.

Reactions of thiols and selenols with the FeMoS cluster [Fe(MoS4)2]3−

Abstract The known complex [Et4N]3[Fe(MoS4)2] has been shown by EPR and visible spectral studies to react with both thiophenol and selenophenol. The reaction results in a change in the characteristic S=3/2 EPR spectrum of this species from a complex rhombic pattern to one of a very simple axial appearance. Although this effect is similar to that observed for reaction of these species with the iron- molybdenum cofactor of nitrogenase, a moiety known to consist of a FeMoS cluster species, the large excesses of reagents and the long reaction times required for complete formation of product indicate that these reactions are of questionable direct relevance to the biological system. The reaction corresponding to the EPR spectral change from rhombic to axial in the [Fe(MoS4)2]3−/PhSeH system has also been partially characterized by product isolation which indicates that attack by selenol of the two terminal MoS2 moieties in the starting material has occurred.