ErMn6Sn6 crystallizes in the hexagonal P6/mmm space group. Er(1) is bonded to two equivalent Sn(3) and six equivalent Sn(1) atoms to form distorted edge-sharing ErSn8 hexagonal bipyramids. Mn(1) is bonded in a 6-coordinate geometry to two equivalent Sn(1), two equivalent Sn(2), and two equivalent Sn(3) atoms. There are three inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a 9-coordinate geometry to three equivalent Er(1) and six equivalent Mn(1) atoms. In the second Sn site, Sn(2) is bonded in a 6-coordinate geometry to six equivalent Mn(1) atoms. In the third Sn site, Sn(3) is bonded in a 8-coordinate geometry to one Er(1), six equivalent Mn(1), and one Sn(3) atom.
ErMn6Sn6 crystallizes in the hexagonal P6/mmm space group. Er(1) is bonded to two equivalent Sn(3) and six equivalent Sn(1) atoms to form distorted edge-sharing ErSn8 hexagonal bipyramids. Both Er(1)-Sn(3) bond lengths are 3.07 Å. All Er(1)-Sn(1) bond lengths are 3.27 Å. Mn(1) is bonded in a 6-coordinate geometry to two equivalent Sn(1), two equivalent Sn(2), and two equivalent Sn(3) atoms. Both Mn(1)-Sn(1) bond lengths are 2.79 Å. Both Mn(1)-Sn(2) bond lengths are 2.84 Å. Both Mn(1)-Sn(3) bond lengths are 2.95 Å. There are three inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a 9-coordinate geometry to three equivalent Er(1) and six equivalent Mn(1) atoms. In the second Sn site, Sn(2) is bonded in a 6-coordinate geometry to six equivalent Mn(1) atoms. In the third Sn site, Sn(3) is bonded in a 8-coordinate geometry to one Er(1), six equivalent Mn(1), and one Sn(3) atom. The Sn(3)-Sn(3) bond length is 3.03 Å.