ErNiSn2 crystallizes in the orthorhombic Pnma space group. There are three inequivalent Er sites. In the first Er site, Er(1) is bonded in a 14-coordinate geometry to one Ni(2), two equivalent Ni(3), three equivalent Ni(1), one Sn(6), two equivalent Sn(1), two equivalent Sn(4), and three equivalent Sn(3) atoms. In the second Er site, Er(2) is bonded in a 11-coordinate geometry to one Ni(3), two equivalent Ni(1), one Sn(1), one Sn(2), one Sn(3), two equivalent Sn(4), two equivalent Sn(5), and two equivalent Sn(6) atoms. In the third Er site, Er(3) is bonded in a 13-coordinate geometry to two equivalent Ni(2), two equivalent Ni(3), one Sn(1), one Sn(6), two equivalent Sn(4), two equivalent Sn(5), and three equivalent Sn(2) atoms. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 10-coordinate geometry to two equivalent Er(2), three equivalent Er(1), one Sn(4), one Sn(5), and three equivalent Sn(3) atoms. In the second Ni site, Ni(2) is bonded in a 7-coordinate geometry to one Er(1), two equivalent Er(3), one Sn(4), one Sn(5), one Sn(6), and two equivalent Sn(1) atoms. In the third Ni site, Ni(3) is bonded in a 10-coordinate geometry to one Er(2), two equivalent Er(1), two equivalent Er(3), one Sn(1), one Sn(2), one Sn(4), and two equivalent Sn(6) atoms. There are six inequivalent Sn sites. In the first Sn site, Sn(3) is bonded in a 8-coordinate geometry to one Er(2), three equivalent Er(1), three equivalent Ni(1), and one Sn(1) atom. In the second Sn site, Sn(4) is bonded in a 9-coordinate geometry to two equivalent Er(1), two equivalent Er(2), two equivalent Er(3), one Ni(1), one Ni(2), and one Ni(3) atom. In the third Sn site, Sn(5) is bonded in a 6-coordinate geometry to two equivalent Er(2), two equivalent Er(3), one Ni(1), and one Ni(2) atom. In the fourth Sn site, Sn(6) is bonded in a 6-coordinate geometry to one Er(1), one Er(3), two equivalent Er(2), one Ni(2), and two equivalent Ni(3) atoms. In the fifth Sn site, Sn(1) is bonded in a 8-coordinate geometry to one Er(2), one Er(3), two equivalent Er(1), one Ni(3), two equivalent Ni(2), and one Sn(3) atom. In the sixth Sn site, Sn(2) is bonded in a 2-coordinate geometry to one Er(2), three equivalent Er(3), and one Ni(3) atom.
ErNiSn2 crystallizes in the orthorhombic Pnma space group. There are three inequivalent Er sites. In the first Er site, Er(1) is bonded in a 14-coordinate geometry to one Ni(2), two equivalent Ni(3), three equivalent Ni(1), one Sn(6), two equivalent Sn(1), two equivalent Sn(4), and three equivalent Sn(3) atoms. The Er(1)-Ni(2) bond length is 3.40 Å. Both Er(1)-Ni(3) bond lengths are 3.27 Å. There are two shorter (3.32 Å) and one longer (3.50 Å) Er(1)-Ni(1) bond length. The Er(1)-Sn(6) bond length is 3.18 Å. Both Er(1)-Sn(1) bond lengths are 3.15 Å. Both Er(1)-Sn(4) bond lengths are 3.10 Å. There is one shorter (3.12 Å) and two longer (3.16 Å) Er(1)-Sn(3) bond lengths. In the second Er site, Er(2) is bonded in a 11-coordinate geometry to one Ni(3), two equivalent Ni(1), one Sn(1), one Sn(2), one Sn(3), two equivalent Sn(4), two equivalent Sn(5), and two equivalent Sn(6) atoms. The Er(2)-Ni(3) bond length is 3.50 Å. Both Er(2)-Ni(1) bond lengths are 3.06 Å. The Er(2)-Sn(1) bond length is 3.35 Å. The Er(2)-Sn(2) bond length is 3.53 Å. The Er(2)-Sn(3) bond length is 3.20 Å. Both Er(2)-Sn(4) bond lengths are 3.15 Å. Both Er(2)-Sn(5) bond lengths are 3.42 Å. Both Er(2)-Sn(6) bond lengths are 3.13 Å. In the third Er site, Er(3) is bonded in a 13-coordinate geometry to two equivalent Ni(2), two equivalent Ni(3), one Sn(1), one Sn(6), two equivalent Sn(4), two equivalent Sn(5), and three equivalent Sn(2) atoms. Both Er(3)-Ni(2) bond lengths are 3.11 Å. Both Er(3)-Ni(3) bond lengths are 3.25 Å. The Er(3)-Sn(1) bond length is 3.26 Å. The Er(3)-Sn(6) bond length is 3.47 Å. Both Er(3)-Sn(4) bond lengths are 3.13 Å. Both Er(3)-Sn(5) bond lengths are 3.48 Å. There is one shorter (3.11 Å) and two longer (3.57 Å) Er(3)-Sn(2) bond lengths. There are three inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 10-coordinate geometry to two equivalent Er(2), three equivalent Er(1), one Sn(4), one Sn(5), and three equivalent Sn(3) atoms. The Ni(1)-Sn(4) bond length is 2.61 Å. The Ni(1)-Sn(5) bond length is 2.68 Å. There are two shorter (2.53 Å) and one longer (2.75 Å) Ni(1)-Sn(3) bond length. In the second Ni site, Ni(2) is bonded in a 7-coordinate geometry to one Er(1), two equivalent Er(3), one Sn(4), one Sn(5), one Sn(6), and two equivalent Sn(1) atoms. The Ni(2)-Sn(4) bond length is 2.54 Å. The Ni(2)-Sn(5) bond length is 2.63 Å. The Ni(2)-Sn(6) bond length is 2.80 Å. Both Ni(2)-Sn(1) bond lengths are 2.50 Å. In the third Ni site, Ni(3) is bonded in a 10-coordinate geometry to one Er(2), two equivalent Er(1), two equivalent Er(3), one Sn(1), one Sn(2), one Sn(4), and two equivalent Sn(6) atoms. The Ni(3)-Sn(1) bond length is 2.67 Å. The Ni(3)-Sn(2) bond length is 2.53 Å. The Ni(3)-Sn(4) bond length is 2.58 Å. Both Ni(3)-Sn(6) bond lengths are 2.56 Å. There are six inequivalent Sn sites. In the first Sn site, Sn(3) is bonded in a 8-coordinate geometry to one Er(2), three equivalent Er(1), three equivalent Ni(1), and one Sn(1) atom. The Sn(3)-Sn(1) bond length is 2.98 Å. In the second Sn site, Sn(4) is bonded in a 9-coordinate geometry to two equivalent Er(1), two equivalent Er(2), two equivalent Er(3), one Ni(1), one Ni(2), and one Ni(3) atom. In the third Sn site, Sn(5) is bonded in a 6-coordinate geometry to two equivalent Er(2), two equivalent Er(3), one Ni(1), and one Ni(2) atom. In the fourth Sn site, Sn(6) is bonded in a 6-coordinate geometry to one Er(1), one Er(3), two equivalent Er(2), one Ni(2), and two equivalent Ni(3) atoms. In the fifth Sn site, Sn(1) is bonded in a 8-coordinate geometry to one Er(2), one Er(3), two equivalent Er(1), one Ni(3), two equivalent Ni(2), and one Sn(3) atom. In the sixth Sn site, Sn(2) is bonded in a 2-coordinate geometry to one Er(2), three equivalent Er(3), and one Ni(3) atom.