Dy2Te3Se crystallizes in the monoclinic Cc space group. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded to one Te(1), one Te(2), two equivalent Te(3), and one Se(1) atom to form a mixture of edge and corner-sharing DyTe4Se trigonal bipyramids. In the second Dy site, Dy(2) is bonded to one Te(1), one Te(3), two equivalent Te(2), and one Se(1) atom to form a mixture of distorted edge and corner-sharing DyTe4Se trigonal bipyramids. There are three inequivalent Te sites. In the first Te site, Te(1) is bonded in a distorted trigonal planar geometry to one Dy(1), one Dy(2), and one Se(1) atom. In the second Te site, Te(2) is bonded in a distorted T-shaped geometry to one Dy(1) and two equivalent Dy(2) atoms. In the third Te site, Te(3) is bonded in a distorted trigonal planar geometry to one Dy(2) and two equivalent Dy(1) atoms. Se(1) is bonded in a 3-coordinate geometry to one Dy(1), one Dy(2), and one Te(1) atom.
Dy2Te3Se crystallizes in the monoclinic Cc space group. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded to one Te(1), one Te(2), two equivalent Te(3), and one Se(1) atom to form a mixture of edge and corner-sharing DyTe4Se trigonal bipyramids. The Dy(1)-Te(1) bond length is 3.13 Å. The Dy(1)-Te(2) bond length is 2.95 Å. Both Dy(1)-Te(3) bond lengths are 3.02 Å. The Dy(1)-Se(1) bond length is 2.82 Å. In the second Dy site, Dy(2) is bonded to one Te(1), one Te(3), two equivalent Te(2), and one Se(1) atom to form a mixture of distorted edge and corner-sharing DyTe4Se trigonal bipyramids. The Dy(2)-Te(1) bond length is 2.94 Å. The Dy(2)-Te(3) bond length is 3.08 Å. There is one shorter (3.01 Å) and one longer (3.02 Å) Dy(2)-Te(2) bond length. The Dy(2)-Se(1) bond length is 2.84 Å. There are three inequivalent Te sites. In the first Te site, Te(1) is bonded in a distorted trigonal planar geometry to one Dy(1), one Dy(2), and one Se(1) atom. The Te(1)-Se(1) bond length is 2.69 Å. In the second Te site, Te(2) is bonded in a distorted T-shaped geometry to one Dy(1) and two equivalent Dy(2) atoms. In the third Te site, Te(3) is bonded in a distorted trigonal planar geometry to one Dy(2) and two equivalent Dy(1) atoms. Se(1) is bonded in a 3-coordinate geometry to one Dy(1), one Dy(2), and one Te(1) atom.