AcSe3 crystallizes in the tetragonal I4/mmm space group. Ac(1) is bonded to four equivalent Se(2) and eight equivalent Se(1) atoms to form a mixture of face, corner, and edge-sharing AcSe12 cuboctahedra. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 8-coordinate geometry to four equivalent Ac(1) and four equivalent Se(1) atoms. In the second Se site, Se(2) is bonded in a square co-planar geometry to four equivalent Ac(1) atoms.
AcSe3 crystallizes in the tetragonal I4/mmm space group. Ac(1) is bonded to four equivalent Se(2) and eight equivalent Se(1) atoms to form a mixture of face, corner, and edge-sharing AcSe12 cuboctahedra. All Ac(1)-Se(2) bond lengths are 3.07 Å. All Ac(1)-Se(1) bond lengths are 3.49 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 8-coordinate geometry to four equivalent Ac(1) and four equivalent Se(1) atoms. All Se(1)-Se(1) bond lengths are 3.07 Å. In the second Se site, Se(2) is bonded in a square co-planar geometry to four equivalent Ac(1) atoms.