Sm(BiSe2)2 crystallizes in the orthorhombic Pnma space group. Sm(1) is bonded to one Se(1), one Se(4), two equivalent Se(2), and two equivalent Se(3) atoms to form SmSe6 octahedra that share corners with three equivalent Bi(1)Se6 octahedra, corners with three equivalent Bi(2)Se6 octahedra, edges with two equivalent Sm(1)Se6 octahedra, edges with two equivalent Bi(2)Se6 octahedra, and edges with three equivalent Bi(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 10-65°. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one Se(1), two equivalent Se(4), and three equivalent Se(3) atoms to form distorted BiSe6 octahedra that share corners with two equivalent Bi(2)Se6 octahedra, corners with three equivalent Sm(1)Se6 octahedra, edges with three equivalent Sm(1)Se6 octahedra, edges with three equivalent Bi(2)Se6 octahedra, and edges with four equivalent Bi(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 7-61°. In the second Bi site, Bi(2) is bonded to one Se(2), two equivalent Se(1), and three equivalent Se(4) atoms to form distorted BiSe6 octahedra that share corners with two equivalent Bi(1)Se6 octahedra, corners with three equivalent Sm(1)Se6 octahedra, edges with two equivalent Sm(1)Se6 octahedra, edges with three equivalent Bi(1)Se6 octahedra, and edges with four equivalent Bi(2)Se6 octahedra. The corner-sharing octahedral tilt angles range from 7-65°. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded to one Sm(1), one Bi(1), and two equivalent Bi(2) atoms to form distorted SeSmBi3 tetrahedra that share corners with three equivalent Se(4)SmBi5 octahedra, corners with five equivalent Se(3)Sm2Bi3 square pyramids, corners with two equivalent Se(1)SmBi3 tetrahedra, and edges with three equivalent Se(4)SmBi5 octahedra. The corner-sharing octahedral tilt angles range from 9-20°. In the second Se site, Se(2) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Sm(1) and one Bi(2) atom. In the third Se site, Se(3) is bonded to two equivalent Sm(1) and three equivalent Bi(1) atoms to form SeSm2Bi3 square pyramids that share corners with two equivalent Se(4)SmBi5 octahedra, corners with five equivalent Se(1)SmBi3 tetrahedra, edges with three equivalent Se(4)SmBi5 octahedra, and edges with four equivalent Se(3)Sm2Bi3 square pyramids. The corner-sharing octahedral tilt angles are 10°. In the fourth Se site, Se(4) is bonded to one Sm(1), two equivalent Bi(1), and three equivalent Bi(2) atoms to form distorted SeSmBi5 octahedra that share corners with two equivalent Se(3)Sm2Bi3 square pyramids, corners with three equivalent Se(1)SmBi3 tetrahedra, edges with four equivalent Se(4)SmBi5 octahedra, edges with three equivalent Se(3)Sm2Bi3 square pyramids, and edges with three equivalent Se(1)SmBi3 tetrahedra.
Sm(BiSe2)2 crystallizes in the orthorhombic Pnma space group. Sm(1) is bonded to one Se(1), one Se(4), two equivalent Se(2), and two equivalent Se(3) atoms to form SmSe6 octahedra that share corners with three equivalent Bi(1)Se6 octahedra, corners with three equivalent Bi(2)Se6 octahedra, edges with two equivalent Sm(1)Se6 octahedra, edges with two equivalent Bi(2)Se6 octahedra, and edges with three equivalent Bi(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 10-65°. The Sm(1)-Se(1) bond length is 2.97 Å. The Sm(1)-Se(4) bond length is 2.94 Å. Both Sm(1)-Se(2) bond lengths are 2.94 Å. Both Sm(1)-Se(3) bond lengths are 3.09 Å. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one Se(1), two equivalent Se(4), and three equivalent Se(3) atoms to form distorted BiSe6 octahedra that share corners with two equivalent Bi(2)Se6 octahedra, corners with three equivalent Sm(1)Se6 octahedra, edges with three equivalent Sm(1)Se6 octahedra, edges with three equivalent Bi(2)Se6 octahedra, and edges with four equivalent Bi(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 7-61°. The Bi(1)-Se(1) bond length is 3.20 Å. Both Bi(1)-Se(4) bond lengths are 2.93 Å. There is one shorter (2.84 Å) and two longer (3.28 Å) Bi(1)-Se(3) bond lengths. In the second Bi site, Bi(2) is bonded to one Se(2), two equivalent Se(1), and three equivalent Se(4) atoms to form distorted BiSe6 octahedra that share corners with two equivalent Bi(1)Se6 octahedra, corners with three equivalent Sm(1)Se6 octahedra, edges with two equivalent Sm(1)Se6 octahedra, edges with three equivalent Bi(1)Se6 octahedra, and edges with four equivalent Bi(2)Se6 octahedra. The corner-sharing octahedral tilt angles range from 7-65°. The Bi(2)-Se(2) bond length is 2.76 Å. Both Bi(2)-Se(1) bond lengths are 2.86 Å. There are two shorter (3.25 Å) and one longer (3.28 Å) Bi(2)-Se(4) bond length. There are four inequivalent Se sites. In the first Se site, Se(1) is bonded to one Sm(1), one Bi(1), and two equivalent Bi(2) atoms to form distorted SeSmBi3 tetrahedra that share corners with three equivalent Se(4)SmBi5 octahedra, corners with five equivalent Se(3)Sm2Bi3 square pyramids, corners with two equivalent Se(1)SmBi3 tetrahedra, and edges with three equivalent Se(4)SmBi5 octahedra. The corner-sharing octahedral tilt angles range from 9-20°. In the second Se site, Se(2) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Sm(1) and one Bi(2) atom. In the third Se site, Se(3) is bonded to two equivalent Sm(1) and three equivalent Bi(1) atoms to form SeSm2Bi3 square pyramids that share corners with two equivalent Se(4)SmBi5 octahedra, corners with five equivalent Se(1)SmBi3 tetrahedra, edges with three equivalent Se(4)SmBi5 octahedra, and edges with four equivalent Se(3)Sm2Bi3 square pyramids. The corner-sharing octahedral tilt angles are 10°. In the fourth Se site, Se(4) is bonded to one Sm(1), two equivalent Bi(1), and three equivalent Bi(2) atoms to form distorted SeSmBi5 octahedra that share corners with two equivalent Se(3)Sm2Bi3 square pyramids, corners with three equivalent Se(1)SmBi3 tetrahedra, edges with four equivalent Se(4)SmBi5 octahedra, edges with three equivalent Se(3)Sm2Bi3 square pyramids, and edges with three equivalent Se(1)SmBi3 tetrahedra.