Cs2Pt3USe6 crystallizes in the orthorhombic Fmmm space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 8-coordinate geometry to four equivalent Se(1) and four equivalent Se(2) atoms. In the second Cs site, Cs(2) is bonded in a 10-coordinate geometry to two equivalent Se(2) and eight equivalent Se(1) atoms. U(1) is bonded in a 6-coordinate geometry to two equivalent Se(2) and four equivalent Se(1) atoms. There are two inequivalent Pt sites. In the first Pt site, Pt(1) is bonded in a distorted square co-planar geometry to two equivalent Se(1) and two equivalent Se(2) atoms. In the second Pt site, Pt(2) is bonded in a square co-planar geometry to four equivalent Se(1) atoms. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to one Cs(1), two equivalent Cs(2), one U(1), one Pt(1), and one Pt(2) atom. In the second Se site, Se(2) is bonded to one Cs(2), two equivalent Cs(1), one U(1), and two equivalent Pt(1) atoms to form a mixture of distorted face, corner, and edge-sharing SeCs3UPt2 octahedra. The corner-sharing octahedral tilt angles range from 28-82°.
Cs2Pt3USe6 crystallizes in the orthorhombic Fmmm space group. There are two inequivalent Cs sites. In the first Cs site, Cs(1) is bonded in a 8-coordinate geometry to four equivalent Se(1) and four equivalent Se(2) atoms. All Cs(1)-Se(1) bond lengths are 3.59 Å. All Cs(1)-Se(2) bond lengths are 3.58 Å. In the second Cs site, Cs(2) is bonded in a 10-coordinate geometry to two equivalent Se(2) and eight equivalent Se(1) atoms. Both Cs(2)-Se(2) bond lengths are 3.82 Å. There are four shorter (3.86 Å) and four longer (4.26 Å) Cs(2)-Se(1) bond lengths. U(1) is bonded in a 6-coordinate geometry to two equivalent Se(2) and four equivalent Se(1) atoms. Both U(1)-Se(2) bond lengths are 2.89 Å. All U(1)-Se(1) bond lengths are 2.86 Å. There are two inequivalent Pt sites. In the first Pt site, Pt(1) is bonded in a distorted square co-planar geometry to two equivalent Se(1) and two equivalent Se(2) atoms. Both Pt(1)-Se(1) bond lengths are 2.51 Å. Both Pt(1)-Se(2) bond lengths are 2.50 Å. In the second Pt site, Pt(2) is bonded in a square co-planar geometry to four equivalent Se(1) atoms. All Pt(2)-Se(1) bond lengths are 2.49 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to one Cs(1), two equivalent Cs(2), one U(1), one Pt(1), and one Pt(2) atom. In the second Se site, Se(2) is bonded to one Cs(2), two equivalent Cs(1), one U(1), and two equivalent Pt(1) atoms to form a mixture of distorted face, corner, and edge-sharing SeCs3UPt2 octahedra. The corner-sharing octahedral tilt angles range from 28-82°.