Li13.7Rh8Si18.3 - A Non-Centrosymmetric Variant of the R-Phase Structure

The suicide Li13.7Rh8Si18.3 was synthesized from the elements in a sealed niobium ampoule at 1370K followed by slow cooling. The sample was studied by powder and single-crystal X-ray diffraction. Li13.7Rh8Si18.3 crystallizes with a non-centrosymmetric occupancy variant of the R-phase structure Mg-32(Al, Zn)(49): I23, a = 1306.9(2) pm, wR2 = 0.0447, 1286 F-2 values, and 53 variables. Striking structural motifs of the Li13.7Rh8Si18.3 structure are M-12 icosahedra and M-60 buckyball-type clusters (M = Si + Rh), both partially built up from mixed-occupied sites.