Soft X-ray emission spectroscopy study of electronic structure of sodium borosilicide Na8B74.5Si17.5

Na3MgB37Si9: an icosahedral B12 cluster framework containing {Si8} units

Single crystals of a novel boride silicide, Na₃MgB₃₇Si₉, containing B₁₂ icosa­hedra and Si₈ units were synthesized from Na, B, Si, B₂O₃ and magnesium vapor.

Single crystals of a novel sodium–magnesium boride silicide, Na₃MgB₃₇Si₉ [a = 10.1630 (3) Å, c = 16.5742 (6) Å, space group Rm (No. 166)], were synthesized by heating a mixture of Na, Si and crystalline B with B₂O₃ flux in Mg vapor at 1373 K. The Mg atoms in the title compound are located at an inter­stitial site of the Dy_2.1B₃₇Si₉-type structure with an occupancy of 0.5. The (001) layers of B₁₂ icosa­hedra stack along the c-axis direction with shifting in the [–a/3, b/3, c/3] direction. A three-dimensional framework structure of the layers is formed via B—Si bonds and {Si₈} units of [Si]₃—Si—Si—[Si]₃.