ErMn2Si2 crystallizes in the tetragonal I4/mmm space group. Er(1) is bonded in a 8-coordinate geometry to eight equivalent Si(1) atoms. Mn(1) is bonded to four equivalent Si(1) atoms to form a mixture of corner and edge-sharing MnSi4 tetrahedra. Si(1) is bonded in a 9-coordinate geometry to four equivalent Er(1), four equivalent Mn(1), and one Si(1) atom.
ErMn2Si2 crystallizes in the tetragonal I4/mmm space group. Er(1) is bonded in a 8-coordinate geometry to eight equivalent Si(1) atoms. All Er(1)-Si(1) bond lengths are 2.98 Å. Mn(1) is bonded to four equivalent Si(1) atoms to form a mixture of corner and edge-sharing MnSi4 tetrahedra. All Mn(1)-Si(1) bond lengths are 2.38 Å. Si(1) is bonded in a 9-coordinate geometry to four equivalent Er(1), four equivalent Mn(1), and one Si(1) atom. The Si(1)-Si(1) bond length is 2.43 Å.