ErSi2 is hexagonal omega structure-like structured and crystallizes in the tetragonal I4_1/amd space group. Er(1) is bonded to twelve equivalent Si(1) atoms to form a mixture of edge and face-sharing ErSi12 cuboctahedra. Si(1) is bonded in a 9-coordinate geometry to six equivalent Er(1) and three equivalent Si(1) atoms.
ErSi2 is hexagonal omega structure-like structured and crystallizes in the tetragonal I4_1/amd space group. Er(1) is bonded to twelve equivalent Si(1) atoms to form a mixture of edge and face-sharing ErSi12 cuboctahedra. There are eight shorter (2.99 Å) and four longer (3.18 Å) Er(1)-Si(1) bond lengths. Si(1) is bonded in a 9-coordinate geometry to six equivalent Er(1) and three equivalent Si(1) atoms. There are two shorter (2.34 Å) and one longer (2.42 Å) Si(1)-Si(1) bond length.