Synthesis, spectroscopic, thermal and X-ray structure characterization of 1,3-propanediammonium tetrathiomolybdate and N,N,N′,N′-tetramethylethylenediammonium tetrathiomolybdate

The title compounds 1,3-propanediammonium tetrathiomolybdate, (1,3-pnH2)[MoS4], 1 and, N,N,N′,N′-tetramethylethylenediammonium tetrathiomolybdate, (tmenH2)[MoS4], 2, were prepared by reacting the ammonium salt of [MoS4]2− with the corresponding organic diamine. In 1 and 2 the organic diamines 1,3-propanediamine (1,3-pn) and N,N,N′,N′-tetramethylethylenediamine (tmen) are present in their diprotonated form. The reaction of 1 or 2 with [Ni(en)3]Cl2 · 2H2O (en is ethylenediamine) results in the formation of the highly insoluble complex tris(ethylenediamine)Ni(II) tetrathiomolybdate, [Ni(en)3][MoS4], in quantitative yields. 1 and 2 have been characterized by chemical analysis, vibrational, UV–Vis and NMR spectroscopy, TG–DTA–MS and single crystal X-ray crystallography. Compound 1 is thermally more stable compared to 2. Both complexes decompose in a single step forming amorphous molybdenum sulfide. The structure of the title complexes can be described as consisting of tetrahedral [MoS4]2− dianions which accept a complex series of H-bonds from the organic dications. The strength and number of these hydrogen bonds affect the Mo–S bond lengths.