Dy3CuSe6 crystallizes in the orthorhombic Pca2_1 space group. There are three inequivalent Dy sites. In the first Dy site, Dy(1) is bonded in a 8-coordinate geometry to one Se(1), one Se(2), two equivalent Se(3), two equivalent Se(4), and two equivalent Se(6) atoms. In the second Dy site, Dy(2) is bonded in a 10-coordinate geometry to two equivalent Cu(1), one Se(2), one Se(6), two equivalent Se(1), two equivalent Se(3), and two equivalent Se(5) atoms. In the third Dy site, Dy(3) is bonded in a 9-coordinate geometry to one Cu(1), one Se(1), one Se(6), two equivalent Se(2), two equivalent Se(4), and two equivalent Se(5) atoms. Cu(1) is bonded in a 4-coordinate geometry to one Dy(3), two equivalent Dy(2), one Se(2), one Se(5), and two equivalent Se(1) atoms. There are six inequivalent Se sites. In the first Se site, Se(5) is bonded in a 5-coordinate geometry to two equivalent Dy(2), two equivalent Dy(3), one Cu(1), and one Se(4) atom. In the second Se site, Se(6) is bonded to one Dy(2), one Dy(3), and two equivalent Dy(1) atoms to form distorted corner-sharing SeDy4 trigonal pyramids. In the third Se site, Se(1) is bonded in a 6-coordinate geometry to one Dy(1), one Dy(3), two equivalent Dy(2), and two equivalent Cu(1) atoms. In the fourth Se site, Se(2) is bonded in a 5-coordinate geometry to one Dy(1), one Dy(2), two equivalent Dy(3), and one Cu(1) atom. In the fifth Se site, Se(3) is bonded in a 5-coordinate geometry to two equivalent Dy(1), two equivalent Dy(2), and one Se(4) atom. In the sixth Se site, Se(4) is bonded in a 6-coordinate geometry to two equivalent Dy(1), two equivalent Dy(3), one Se(3), and one Se(5) atom.
Dy3CuSe6 crystallizes in the orthorhombic Pca2_1 space group. There are three inequivalent Dy sites. In the first Dy site, Dy(1) is bonded in a 8-coordinate geometry to one Se(1), one Se(2), two equivalent Se(3), two equivalent Se(4), and two equivalent Se(6) atoms. The Dy(1)-Se(1) bond length is 3.02 Å. The Dy(1)-Se(2) bond length is 2.98 Å. There is one shorter (3.02 Å) and one longer (3.10 Å) Dy(1)-Se(3) bond length. There is one shorter (3.02 Å) and one longer (3.06 Å) Dy(1)-Se(4) bond length. There is one shorter (2.78 Å) and one longer (2.79 Å) Dy(1)-Se(6) bond length. In the second Dy site, Dy(2) is bonded in a 10-coordinate geometry to two equivalent Cu(1), one Se(2), one Se(6), two equivalent Se(1), two equivalent Se(3), and two equivalent Se(5) atoms. There is one shorter (3.12 Å) and one longer (3.15 Å) Dy(2)-Cu(1) bond length. The Dy(2)-Se(2) bond length is 3.10 Å. The Dy(2)-Se(6) bond length is 2.97 Å. Both Dy(2)-Se(1) bond lengths are 2.96 Å. There is one shorter (3.03 Å) and one longer (3.06 Å) Dy(2)-Se(3) bond length. There is one shorter (2.97 Å) and one longer (3.04 Å) Dy(2)-Se(5) bond length. In the third Dy site, Dy(3) is bonded in a 9-coordinate geometry to one Cu(1), one Se(1), one Se(6), two equivalent Se(2), two equivalent Se(4), and two equivalent Se(5) atoms. The Dy(3)-Cu(1) bond length is 3.06 Å. The Dy(3)-Se(1) bond length is 3.17 Å. The Dy(3)-Se(6) bond length is 2.92 Å. There is one shorter (2.86 Å) and one longer (2.90 Å) Dy(3)-Se(2) bond length. There is one shorter (3.04 Å) and one longer (3.08 Å) Dy(3)-Se(4) bond length. There is one shorter (3.06 Å) and one longer (3.13 Å) Dy(3)-Se(5) bond length. Cu(1) is bonded in a 4-coordinate geometry to one Dy(3), two equivalent Dy(2), one Se(2), one Se(5), and two equivalent Se(1) atoms. The Cu(1)-Se(2) bond length is 2.52 Å. The Cu(1)-Se(5) bond length is 2.42 Å. There is one shorter (2.42 Å) and one longer (2.53 Å) Cu(1)-Se(1) bond length. There are six inequivalent Se sites. In the first Se site, Se(5) is bonded in a 5-coordinate geometry to two equivalent Dy(2), two equivalent Dy(3), one Cu(1), and one Se(4) atom. The Se(5)-Se(4) bond length is 3.01 Å. In the second Se site, Se(6) is bonded to one Dy(2), one Dy(3), and two equivalent Dy(1) atoms to form distorted corner-sharing SeDy4 trigonal pyramids. In the third Se site, Se(1) is bonded in a 6-coordinate geometry to one Dy(1), one Dy(3), two equivalent Dy(2), and two equivalent Cu(1) atoms. In the fourth Se site, Se(2) is bonded in a 5-coordinate geometry to one Dy(1), one Dy(2), two equivalent Dy(3), and one Cu(1) atom. In the fifth Se site, Se(3) is bonded in a 5-coordinate geometry to two equivalent Dy(1), two equivalent Dy(2), and one Se(4) atom. The Se(3)-Se(4) bond length is 2.46 Å. In the sixth Se site, Se(4) is bonded in a 6-coordinate geometry to two equivalent Dy(1), two equivalent Dy(3), one Se(3), and one Se(5) atom.