Solvothermal synthesis of a new 3-D mixed-metal sulfide framework, (H1.33tren)[In2.67Sb1.33S8]·tren

•Preparation and structural characterisation of a new mixed-metal thiometallate.•The first mixed In(III)/Sb(V) supertetrahedron.•Optical band gap of 2.7(2) eV.•Soaking in aqueous alkali-metal solutions leads to removal of ca. 50% of the organic content.

A new indium(III) antimony(V) sulfide, (H1.33tren)[In2.67Sb1.33S8]·tren, has been prepared solvothermally at 433 K. The compound crystallises in the tetragonal space group I-42d (lattice parameters, a=12.6248(5) and c=19.4387(18) Å at 150 K) and contains adamantane-like T2 supertetrahedral units comprised of corner-sharing InS45− and SbS43− tetrahedra. The adamantane-like units are then linked through sulfur vertices to generate an open, 3-D framework structure containing large pores in which neutral, protonated tren (tris(2-aminoethylene)amine) molecules reside. The presence of the organic components was confirmed by solid-state 13C NMR (10 kHz), combustion and thermogravimetric analysis. The band gap, obtained from UV–vis diffuse reflectance measurements, is 2.7(2) eV. Stirring with either water or alkali-metal salt solution leads to removal of the neutral tren molecules and an ~9% reduction in unit-cell volume on formation of (H1.33tren)[In2.67Sb1.33S8]·(H2O)4.

Graphical abstractLinking of In(III)-Sb(V)-S adamantane units to form a 3-D open framework.Figure optionsDownload full-size imageDownload as PowerPoint slide