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 4adamantine 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 I4 h3d with cell parameter a ) 20.629 (1) Å. Fourteen unique weak reflections of the type hhl, 2h + l ) 4n + 2, forbidden in I4 h3d, were detected only in the synchrotron/imaging plate experiment. Trial refinements in space groups R3 and I2 1 3 suggest their origin in either weak ordering or multiple scattering effects. diffraction pattern is similar to that of TMA-CoMnGS-2. 1,7 This compound (Figure 1) crystallizes as a framework consisting of two building units, 4-connected Ge 4 S 10 4adamantine and 3-connected MS 4 (M ) Mn/ Co) clusters. 7 Each Ge 4 S 10 4is corner-sharing only with MS 4 and vice versa, forming a (3,4)-connected open framework. The composition of this framework is 3 × (Ge 4 S 8 ) + 4 × (MS 2.5 ) ) Ge 12 M 4 S 34 , which normalizes to Ge 0.71 M 0.24 S 2 (possible protons attached to the framework are neglected). If TMA-CuGS-2 were isostructural with TMA-MnCoGS-2, the framework should be consistent with this composition. Instead the chemical analysis reported for the CuGS-2 material is Ge 0.89 -Cu 0.11 S 2 . 1 In this paper, we report the hydrothermal synthesis, composition, and structural analysis of TMA-CuGS-2 single crystals. For structural studies, besides conventional single-crystal diffractometry, synchrotron radiation in combination with an imaging plate (IP)
