UGd2Se5 crystallizes in the orthorhombic Pnma space group. U(1) is bonded in a 7-coordinate geometry to one Se(2), one Se(3), one Se(4), and four equivalent Se(1) atoms. Gd(1) is bonded in a 8-coordinate geometry to two equivalent Se(1), two equivalent Se(2), two equivalent Se(3), and two equivalent Se(4) atoms. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a rectangular see-saw-like geometry to two equivalent U(1) and two equivalent Gd(1) atoms. In the second Se site, Se(2) is bonded to one U(1) and four equivalent Gd(1) atoms to form a mixture of distorted corner and edge-sharing SeGd4U trigonal bipyramids. In the third Se site, Se(3) is bonded to one U(1) and four equivalent Gd(1) atoms to form a mixture of corner, edge, and face-sharing SeGd4U square pyramids. In the fourth Se site, Se(4) is bonded to one U(1) and four equivalent Gd(1) atoms to form a mixture of distorted corner, edge, and face-sharing SeGd4U square pyramids.
UGd2Se5 crystallizes in the orthorhombic Pnma space group. U(1) is bonded in a 7-coordinate geometry to one Se(2), one Se(3), one Se(4), and four equivalent Se(1) atoms. The U(1)-Se(2) bond length is 2.86 Å. The U(1)-Se(3) bond length is 2.96 Å. The U(1)-Se(4) bond length is 2.92 Å. There are two shorter (2.76 Å) and two longer (2.83 Å) U(1)-Se(1) bond lengths. Gd(1) is bonded in a 8-coordinate geometry to two equivalent Se(1), two equivalent Se(2), two equivalent Se(3), and two equivalent Se(4) atoms. There is one shorter (2.96 Å) and one longer (2.99 Å) Gd(1)-Se(1) bond length. There is one shorter (3.04 Å) and one longer (3.10 Å) Gd(1)-Se(2) bond length. There is one shorter (2.97 Å) and one longer (3.03 Å) Gd(1)-Se(3) bond length. There is one shorter (2.97 Å) and one longer (2.99 Å) Gd(1)-Se(4) bond length. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded in a rectangular see-saw-like geometry to two equivalent U(1) and two equivalent Gd(1) atoms. In the second Se site, Se(2) is bonded to one U(1) and four equivalent Gd(1) atoms to form a mixture of distorted corner and edge-sharing SeGd4U trigonal bipyramids. In the third Se site, Se(3) is bonded to one U(1) and four equivalent Gd(1) atoms to form a mixture of corner, edge, and face-sharing SeGd4U square pyramids. In the fourth Se site, Se(4) is bonded to one U(1) and four equivalent Gd(1) atoms to form a mixture of distorted corner, edge, and face-sharing SeGd4U square pyramids.