Hydrothermal Growth of Single Crystals of TMA-CuGS-2, [C₄H₁₂N]₆[(Cu_0.44Ge_0.56S_2.23)₄(Ge₄S₈)₃] and Their Characterization Using Synchrotron/Imaging Plate Data

Abstract

Single crystals of TMA-CuGS-2, [C4H12N]6[(Cu0.44Ge0.56S2.23)4(Ge4S8)3], were synthesized hydrothermally, and the structure was determined using data collected from sealed-tube and synchrotron X-ray sources. This compound consists of Ge4S104- adamantine clusters, corner-sharing with MSx 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, Ge0.71M0.24S2, 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 I4̄3d with cell parameter a = 20.629 (1) Å. Fourteen unique weak reflections of the type hhl, 2h + l = 4n + 2, forbidden in I4̄3d, were detected only in the synchrotron/imaging plate experiment. Trial refinements in space groups R3 and I213 suggest their origin in either weak ordering or multiple scattering effects.