Hydrothermal Growth of Single Crystals of TMA-CuGS-2, [C4H12N]6[(Cu0.44Ge0.56S2.23)4(Ge4S8)3] and Their Characterization Using Synchrotron/Imaging Plate Data

Single crystals of TMA-CuGS-2, [C 4 H 12 N] 6 [(Cu 0.44 Ge 0.56 S 2.23 ) 4 (Ge 4 S 8 ) 3 ], were synthesized hydrothermally, and the structure was determined using data collected from sealed-tube and synchrotron X-ray sources. This compound consists of Ge 4 S 10 4- adamantine clusters, corner-sharing with MS x units (M = Cu, Ge; x = 3 or 4), forming an open framework with tetramethylammonium cations residing within four intersecting channels. Disorder in the M sites causes the composition of the framework to deviate from the ideal stoichiometry, Ge 0.71 M 0.24 S 2, realized when M = Cu and x = 4. This is consistent with results obtained from electron-probe microanalysis. The structure refinements were carried out in space group I 4̄3 d with cell parameter a = 20.629 (1) Å. Fourteen unique weak reflections of the type hhl, 2 h + l = 4 n + 2, forbidden in I 4̄3 d, were detected only in the synchrotron/imaging plate experiment. Trial refinements in space groups R 3 and I 2 1 3 suggest their origin in either weak ordering or multiple scattering effects.