ErAlSi crystallizes in the tetragonal I4_1md space group. Er(1) is bonded to six equivalent Al(1) and six equivalent Si(1) atoms to form a mixture of face and edge-sharing ErAl6Si6 cuboctahedra. Al(1) is bonded in a distorted trigonal planar geometry to six equivalent Er(1) and three equivalent Si(1) atoms. Si(1) is bonded in a distorted trigonal planar geometry to six equivalent Er(1) and three equivalent Al(1) atoms.
ErAlSi crystallizes in the tetragonal I4_1md space group. Er(1) is bonded to six equivalent Al(1) and six equivalent Si(1) atoms to form a mixture of face and edge-sharing ErAl6Si6 cuboctahedra. There are four shorter (3.13 Å) and two longer (3.14 Å) Er(1)-Al(1) bond lengths. There are four shorter (3.11 Å) and two longer (3.19 Å) Er(1)-Si(1) bond lengths. Al(1) is bonded in a distorted trigonal planar geometry to six equivalent Er(1) and three equivalent Si(1) atoms. There are two shorter (2.38 Å) and one longer (2.39 Å) Al(1)-Si(1) bond length. Si(1) is bonded in a distorted trigonal planar geometry to six equivalent Er(1) and three equivalent Al(1) atoms.