YbAl2Si2 crystallizes in the trigonal P-3m1 space group. Yb(1) is bonded to six equivalent Si(1) atoms to form YbSi6 octahedra that share corners with twelve equivalent Al(1)Si4 tetrahedra, edges with six equivalent Yb(1)Si6 octahedra, and edges with six equivalent Al(1)Si4 tetrahedra. Al(1) is bonded to four equivalent Si(1) atoms to form AlSi4 tetrahedra that share corners with six equivalent Yb(1)Si6 octahedra, corners with six equivalent Al(1)Si4 tetrahedra, edges with three equivalent Yb(1)Si6 octahedra, and edges with three equivalent Al(1)Si4 tetrahedra. The corner-sharing octahedral tilt angles range from 20-52°. Si(1) is bonded to three equivalent Yb(1) and four equivalent Al(1) atoms to form a mixture of distorted corner and edge-sharing SiYb3Al4 pentagonal bipyramids.
YbAl2Si2 crystallizes in the trigonal P-3m1 space group. Yb(1) is bonded to six equivalent Si(1) atoms to form YbSi6 octahedra that share corners with twelve equivalent Al(1)Si4 tetrahedra, edges with six equivalent Yb(1)Si6 octahedra, and edges with six equivalent Al(1)Si4 tetrahedra. All Yb(1)-Si(1) bond lengths are 3.01 Å. Al(1) is bonded to four equivalent Si(1) atoms to form AlSi4 tetrahedra that share corners with six equivalent Yb(1)Si6 octahedra, corners with six equivalent Al(1)Si4 tetrahedra, edges with three equivalent Yb(1)Si6 octahedra, and edges with three equivalent Al(1)Si4 tetrahedra. The corner-sharing octahedral tilt angles range from 20-52°. There are three shorter (2.50 Å) and one longer (2.59 Å) Al(1)-Si(1) bond length. Si(1) is bonded to three equivalent Yb(1) and four equivalent Al(1) atoms to form a mixture of distorted corner and edge-sharing SiYb3Al4 pentagonal bipyramids.