SmSe2 crystallizes in the tetragonal P4/nmm space group. Sm(1) is bonded in a 9-coordinate geometry to four equivalent Se(1) and five equivalent Se(2) atoms. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 8-coordinate geometry to four equivalent Sm(1) and four equivalent Se(1) atoms. In the second Se site, Se(2) is bonded to five equivalent Sm(1) atoms to form a mixture of distorted corner and edge-sharing SeSm5 trigonal bipyramids.
SmSe2 crystallizes in the tetragonal P4/nmm space group. Sm(1) is bonded in a 9-coordinate geometry to four equivalent Se(1) and five equivalent Se(2) atoms. All Sm(1)-Se(1) bond lengths are 3.10 Å. There are four shorter (3.02 Å) and one longer (3.04 Å) Sm(1)-Se(2) bond length. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 8-coordinate geometry to four equivalent Sm(1) and four equivalent Se(1) atoms. All Se(1)-Se(1) bond lengths are 2.91 Å. In the second Se site, Se(2) is bonded to five equivalent Sm(1) atoms to form a mixture of distorted corner and edge-sharing SeSm5 trigonal bipyramids.