Astrid Leist, Sandra Stauf, Sandra Löken, E. Wolfgang Finckh, Silke Lüdtke, Klaus K. Unger, Wolfgang Assenmacher, Werner Mader and Wolfgang Tremel
The decomposition of three different ammonium thiomolybdates (NH4)2MoS4xH2O, (NH4)2Mo2S12xH2O, and (NH4)2Mo3S13xH2O (x=1–2) have been studied by TG–DSC under argon. While all three thiomolybdates decompose at around 673 K to yield nearly X-ray amorphous MoS2 , the precursor (NH4)2Mo3S13xH2O does so in a manner distinct from the other two precursors displaying a sharp exothermic peak in the DSC trace. We suggest that the unusual thermal behaviour of (NH4)2Mo3S13xH2O might arise from a topochemical relation between the molecular cluster and 2H-MoS2 as proposed previously. The porosity of the X-ray amorphous MoS2 obtained from the decomposition under vacuum of (NH4)2Mo3S13xH2O is unusually large and the material displays interesting sorption behaviour towards small organic molecules. This X-ray amorphous semiporous modification of MoS2 has been characterized in detail by powder X-ray diffraction, high resolution electron microscopy and from its extended X-ray absorption fine structure. An unusual feature of this material is the presence of bent, open-ended lamellae of MoS2 , contrasting fullerene-like MoS2 which forms closed shells.