Pt5Se4 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Pt sites. In the first Pt site, Pt(1) is bonded to one Pt(1), one Pt(2), one Pt(3), one Se(1), and two equivalent Se(2) atoms to form distorted PtPt3Se3 octahedra that share  a cornercorner with one Pt(1)Pt3Se3 octahedra, corners with two equivalent Se(2)Pt4 tetrahedra, corners with three equivalent Se(1)Pt4 tetrahedra,  an edgeedge with one Pt(1)Pt3Se3 octahedra,  an edgeedge with one Se(1)Pt4 tetrahedra, and  an edgeedge with one Se(2)Pt4 tetrahedra. The corner-sharing octahedra are not tilted. In the second Pt site, Pt(2) is bonded in a 6-coordinate geometry to one Pt(1), one Pt(3), two equivalent Se(1), and two equivalent Se(2) atoms. In the third Pt site, Pt(3) is bonded in a distorted linear geometry to two equivalent Pt(1), two equivalent Pt(2), and two equivalent Se(1) atoms. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one Pt(1), one Pt(3), and two equivalent Pt(2) atoms to form SePt4 tetrahedra that share corners with three equivalent Pt(1)Pt3Se3 octahedra, corners with three equivalent Se(1)Pt4 tetrahedra, corners with six equivalent Se(2)Pt4 tetrahedra, and  an edgeedge with one Pt(1)Pt3Se3 octahedra. The corner-sharing octahedral tilt angles range from 14-85°. In the second Se site, Se(2) is bonded to two equivalent Pt(1) and two equivalent Pt(2) atoms to form SePt4 tetrahedra that share corners with two equivalent Pt(1)Pt3Se3 octahedra, corners with two equivalent Se(2)Pt4 tetrahedra, corners with six equivalent Se(1)Pt4 tetrahedra,  an edgeedge with one Pt(1)Pt3Se3 octahedra, and  an edgeedge with one Se(2)Pt4 tetrahedra. The corner-sharing octahedral tilt angles are 83°.
Pt5Se4 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Pt sites. In the first Pt site, Pt(1) is bonded to one Pt(1), one Pt(2), one Pt(3), one Se(1), and two equivalent Se(2) atoms to form distorted PtPt3Se3 octahedra that share  a cornercorner with one Pt(1)Pt3Se3 octahedra, corners with two equivalent Se(2)Pt4 tetrahedra, corners with three equivalent Se(1)Pt4 tetrahedra,  an edgeedge with one Pt(1)Pt3Se3 octahedra,  an edgeedge with one Se(1)Pt4 tetrahedra, and  an edgeedge with one Se(2)Pt4 tetrahedra. The corner-sharing octahedra are not tilted. The Pt(1)-Pt(1) bond length is 2.73 Å. The Pt(1)-Pt(2) bond length is 2.66 Å. The Pt(1)-Pt(3) bond length is 2.68 Å. The Pt(1)-Se(1) bond length is 2.46 Å. There is one shorter (2.49 Å) and one longer (2.50 Å) Pt(1)-Se(2) bond length. In the second Pt site, Pt(2) is bonded in a 6-coordinate geometry to one Pt(1), one Pt(3), two equivalent Se(1), and two equivalent Se(2) atoms. The Pt(2)-Pt(3) bond length is 2.70 Å. There is one shorter (2.45 Å) and one longer (2.63 Å) Pt(2)-Se(1) bond length. There is one shorter (2.45 Å) and one longer (2.59 Å) Pt(2)-Se(2) bond length. In the third Pt site, Pt(3) is bonded in a distorted linear geometry to two equivalent Pt(1), two equivalent Pt(2), and two equivalent Se(1) atoms. Both Pt(3)-Se(1) bond lengths are 2.45 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one Pt(1), one Pt(3), and two equivalent Pt(2) atoms to form SePt4 tetrahedra that share corners with three equivalent Pt(1)Pt3Se3 octahedra, corners with three equivalent Se(1)Pt4 tetrahedra, corners with six equivalent Se(2)Pt4 tetrahedra, and  an edgeedge with one Pt(1)Pt3Se3 octahedra. The corner-sharing octahedral tilt angles range from 14-85°. In the second Se site, Se(2) is bonded to two equivalent Pt(1) and two equivalent Pt(2) atoms to form SePt4 tetrahedra that share corners with two equivalent Pt(1)Pt3Se3 octahedra, corners with two equivalent Se(2)Pt4 tetrahedra, corners with six equivalent Se(1)Pt4 tetrahedra,  an edgeedge with one Pt(1)Pt3Se3 octahedra, and  an edgeedge with one Se(2)Pt4 tetrahedra. The corner-sharing octahedral tilt angles are 83°.