Cr3Se4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form a mixture of corner, edge, and face-sharing CrSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-52°. In the second Cr site, Cr(2) is bonded to three equivalent Se(1) and three equivalent Se(2) atoms to form a mixture of corner, edge, and face-sharing CrSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-52°. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent Cr(1) and three equivalent Cr(2) atoms to form a mixture of distorted corner and edge-sharing SeCr5 trigonal bipyramids. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to one Cr(1) and three equivalent Cr(2) atoms.
Cr3Se4 crystallizes in the monoclinic C2/m space group. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent Se(2) and four equivalent Se(1) atoms to form a mixture of corner, edge, and face-sharing CrSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-52°. Both Cr(1)-Se(2) bond lengths are 2.60 Å. All Cr(1)-Se(1) bond lengths are 2.62 Å. In the second Cr site, Cr(2) is bonded to three equivalent Se(1) and three equivalent Se(2) atoms to form a mixture of corner, edge, and face-sharing CrSe6 octahedra. The corner-sharing octahedral tilt angles range from 48-52°. There is one shorter (2.60 Å) and two longer (2.65 Å) Cr(2)-Se(1) bond lengths. There are two shorter (2.50 Å) and one longer (2.54 Å) Cr(2)-Se(2) bond length. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to two equivalent Cr(1) and three equivalent Cr(2) atoms to form a mixture of distorted corner and edge-sharing SeCr5 trigonal bipyramids. In the second Se site, Se(2) is bonded in a rectangular see-saw-like geometry to one Cr(1) and three equivalent Cr(2) atoms.