U2TlSe6 crystallizes in the orthorhombic Immm space group. U(1) is bonded in a 8-coordinate geometry to four equivalent Se(1) and four equivalent Se(2) atoms. Tl(1) is bonded in a 8-coordinate geometry to eight equivalent Se(2) atoms. There are two inequivalent Se sites. In the first Se site, Se(2) is bonded in a distorted L-shaped geometry to two equivalent U(1) and two equivalent Tl(1) atoms. In the second Se site, Se(1) is bonded to four equivalent U(1) atoms to form a mixture of distorted corner and edge-sharing SeU4 trigonal pyramids.
U2TlSe6 crystallizes in the orthorhombic Immm space group. U(1) is bonded in a 8-coordinate geometry to four equivalent Se(1) and four equivalent Se(2) atoms. There are two shorter (2.89 Å) and two longer (2.97 Å) U(1)-Se(1) bond lengths. All U(1)-Se(2) bond lengths are 2.94 Å. Tl(1) is bonded in a 8-coordinate geometry to eight equivalent Se(2) atoms. All Tl(1)-Se(2) bond lengths are 3.41 Å. There are two inequivalent Se sites. In the first Se site, Se(2) is bonded in a distorted L-shaped geometry to two equivalent U(1) and two equivalent Tl(1) atoms. In the second Se site, Se(1) is bonded to four equivalent U(1) atoms to form a mixture of distorted corner and edge-sharing SeU4 trigonal pyramids.