Zero- and one-dimensional thioindates synthesized under solvothermal conditions yielding α-In2S3, β-In2S3 or MgIn2S4 as thermal decomposition products

The first cationic thioindate with composition [In(en)2S]2·2Cl (zero-dimensional) (1) and the first thioindate being charge compensated by a main group metal complex with composition [Mg(en)3][In2S4] (one-dimensional) (2) have been prepared with ethylenediamine under solvothermal conditions. The main structural motif of [In(en)2S]2·2Cl is the centro-symmetric rhomboidal [In(en)2S]22+ ring which is formed by S–S edge-sharing of two symmetry related [InN4S2] octahedra. The structure of [Mg(en)3][In2S4] is composed of a straight one-dimensional {[InS2]−}∞ chain surrounded by [Mg(en)3]2+ complexes. Both compounds are wide band-gap semiconductors. The thermal decomposition reaction of [In(en)2S]2·2Cl stopped at 500 °C yielded cubic α-In2S3 and reflections of β-In2S3 are seen in the X-ray powder pattern of the residue obtained at 900 °C. In the case of [Mg(en)3][In2S4] the thiospinel MgIn2S4 was identified as decomposition product. The size of the MgIn2S4 crystals are in the nanometer range as evidenced by a pronounced broadening of the reflections in the powder pattern and with transmission electron microscopy.

The structure of [In(en)2S]2·2Cl contains a cationic core and [Mg(en)3][In2S4] is the first thioindate with a charge compensating Mg2+ complex. Thermal decomposition yields α- or β-In2S3 resp. spinel-type nanocrystalline MgIn2S4.Figure optionsDownload as PowerPoint slide