A Novel Antimony Sulfide Templated by Dimethylammonium: Its Synthesis and Structural Characterization Using Synchrotron/Imaging Plate Data

Hydrothermal synthesis at 200 °C produced a new open antimony sulfide framework, [C₂H₈N]₂[Sb₈S₁₂(S ₂)], designated DMA-SbS-SB8. The structure (Cmca, a = 9.9704(7), b = 11.652(2), and c = 25.979(3) Å), determined from data collected on a small single crystal (20 × 30 × 40 μm in size) utilizing the synchrotron/imaging plate system installed at the X3A1 beamline of the NSLS, consists of [Sb₈S₁₂(S₂)]^2- double chains formed from Sb₄S₇^2- single chains joined through S-S bridges. The double chains contain 18-membered Sb₈S₁₀ rings and are interlocked to form sheets perpendicular to the b axis. Dimethylammonium ions, assumed to be protonated to charge balance the anionic [Sb₈S₁₂(S₂)]^2- framework, reside within 18-membered rings. The structural building units of the new open framework are similar to those described previously in other members of the antimony sulfide system. Experiments carried out at different temperatures and reaction times show that DMA-SbS-SB8 is formed from a distinct poorly crystallized phase (designated DMA-SbS-SB8′), which is the dominant phase at 100 °C.