On the crystal structure of Sc2MB6 (M = Rh, Ir) compounds

Ternary samples Sc2MB6 and ScMB4 (M = Rh, Ir) were synthesized and studied by X-ray powder and single crystal diffraction. The crystal structure of the ternary boride Sc2RhB6, Y2ReB6 structure type, Pbam space group, a = 8.9144(8) A, b = 11.2105(10) A, c = 3.4833(3) A, Z=4, V=348.10(5)A3, rho=4.917g cm-3, m=8.216 mm-1 was refined to R=0.0193, wR2=0.0518 from single crystal X-ray diffraction data (Broker SMART 100 CCD diffractometer, 573 reflections with I > 2sigma(Io). The lattice parameters for the isotypic Sc2IrB6 compound are a = 8.9149(18) A, b = 11.211(19) A, c = 3.48367(13) A (X-ray powder diffraction, Image Plate Huber G 670 camera). No evidence of formation of the ternary ScMB4 (M = Rh, Ir) compounds with YReB4 structure type was obtained.