fig1

Figure 1. Crystal structure of 5p-block element nitrides MN₆ (M = Sb, Te, I). (A) MN₆ has $$ R\bar{3}m $$ space group; (B) Rhombohedral primitive cell structure without showing any M–N bonds, and the chair-like N₆ hexazine ring is located in the center; (C) The hypercoordinated MN₁₂ icosahedral cage. The large pink spheres and small yellow spheres represent the 5p-block elements and nitrogen, respectively.