We wish to exploit the contrast afforded by neutrons to study the ordering of In and Sn cations in indium tin chalcogenides. Cation ordering has been inferred from spectroscopic data for materials formulated as In2Sn3S7. Our synthetic studies suggest a very different In:Sn ratio (In1.67Sn3.33S7), casting doubt on the correctness of the proposed ordering scheme. We seek to establish the cation-ordered structures of In1.67Sn3.33Q7 (Q= S = Se). Given the key importance of the 600-900C region to synthesis, we will study the evolution of structure with temperature to 900C Replacement of In3+ by Cr3+ produces an isostructural material for which magnetic susceptibility data indicate long-range magnetic order on cooling below TN=12 K. We propose to investigate the nature of this magnetically ordered phase at 2K and at temperatures through the magnetic ordering transition.