Na9Sm(SiSe3)4 crystallizes in the monoclinic C2 space group. There are six inequivalent Na sites. In the first Na site, Na(1) is bonded to one Se(1), one Se(2), one Se(3), one Se(4), one Se(5), and one Se(6) atom to form NaSe6 octahedra that share  a cornercorner with one Na(4)Se6 octahedra,  a cornercorner with one Na(5)Se6 octahedra,  a cornercorner with one Na(6)Se6 octahedra,  a cornercorner with one Sm(1)Se6 octahedra,  a cornercorner with one Si(2)SiSe3 tetrahedra,  an edgeedge with one Na(4)Se6 octahedra,  an edgeedge with one Na(5)Se6 octahedra,  an edgeedge with one Na(6)Se6 octahedra,  an edgeedge with one Sm(1)Se6 octahedra, edges with three equivalent Na(2)Se6 octahedra, edges with three equivalent Na(3)Se6 octahedra, and  an edgeedge with one Si(2)SiSe3 tetrahedra. The corner-sharing octahedral tilt angles range from 5-8°. In the second Na site, Na(2) is bonded to one Se(1), one Se(2), one Se(3), one Se(4), one Se(5), and one Se(6) atom to form NaSe6 octahedra that share  a cornercorner with one Na(4)Se6 octahedra,  a cornercorner with one Na(5)Se6 octahedra,  a cornercorner with one Na(6)Se6 octahedra,  a cornercorner with one Sm(1)Se6 octahedra,  a cornercorner with one Si(2)SiSe3 tetrahedra,  an edgeedge with one Na(4)Se6 octahedra,  an edgeedge with one Na(5)Se6 octahedra,  an edgeedge with one Na(6)Se6 octahedra,  an edgeedge with one Sm(1)Se6 octahedra, edges with three equivalent Na(1)Se6 octahedra, edges with three equivalent Na(3)Se6 octahedra, and  an edgeedge with one Si(2)SiSe3 tetrahedra. The corner-sharing octahedral tilt angles range from 6-9°. In the third Na site, Na(3) is bonded to one Se(1), one Se(2), one Se(3), one Se(4), one Se(5), and one Se(6) atom to form NaSe6 octahedra that share  a cornercorner with one Na(4)Se6 octahedra,  a cornercorner with one Na(5)Se6 octahedra,  a cornercorner with one Na(6)Se6 octahedra,  a cornercorner with one Sm(1)Se6 octahedra,  a cornercorner with one Si(2)SiSe3 tetrahedra,  an edgeedge with one Na(4)Se6 octahedra,  an edgeedge with one Na(5)Se6 octahedra,  an edgeedge with one Na(6)Se6 octahedra,  an edgeedge with one Sm(1)Se6 octahedra, edges with three equivalent Na(1)Se6 octahedra, edges with three equivalent Na(2)Se6 octahedra, and  an edgeedge with one Si(2)SiSe3 tetrahedra. The corner-sharing octahedral tilt angles range from 7-8°. In the fourth Na site, Na(4) is bonded to two equivalent Se(2), two equivalent Se(3), and two equivalent Se(5) atoms to form NaSe6 octahedra that share corners with two equivalent Na(1)Se6 octahedra, corners with two equivalent Na(2)Se6 octahedra, corners with two equivalent Na(3)Se6 octahedra, corners with two equivalent Si(2)SiSe3 tetrahedra,  an edgeedge with one Na(6)Se6 octahedra, edges with two equivalent Na(1)Se6 octahedra, edges with two equivalent Na(2)Se6 octahedra, edges with two equivalent Na(3)Se6 octahedra, and edges with two equivalent Na(5)Se6 octahedra. The corner-sharing octahedral tilt angles range from 6-8°. In the fifth Na site, Na(5) is bonded to two equivalent Se(2), two equivalent Se(3), and two equivalent Se(6) atoms to form NaSe6 octahedra that share corners with two equivalent Na(1)Se6 octahedra, corners with two equivalent Na(2)Se6 octahedra, corners with two equivalent Na(3)Se6 octahedra, corners with four equivalent Si(2)SiSe3 tetrahedra,  an edgeedge with one Sm(1)Se6 octahedra, edges with two equivalent Na(1)Se6 octahedra, edges with two equivalent Na(2)Se6 octahedra, edges with two equivalent Na(3)Se6 octahedra, and edges with two equivalent Na(4)Se6 octahedra. The corner-sharing octahedral tilt angles range from 5-9°. In the sixth Na site, Na(6) is bonded to two equivalent Se(1), two equivalent Se(4), and two equivalent Se(5) atoms to form NaSe6 octahedra that share corners with two equivalent Na(1)Se6 octahedra, corners with two equivalent Na(2)Se6 octahedra, corners with two equivalent Na(3)Se6 octahedra, corners with two equivalent Si(2)SiSe3 tetrahedra,  an edgeedge with one Na(4)Se6 octahedra, edges with two equivalent Na(1)Se6 octahedra, edges with two equivalent Na(2)Se6 octahedra, edges with two equivalent Na(3)Se6 octahedra, and edges with two equivalent Sm(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 7-8°. Sm(1) is bonded to two equivalent Se(1), two equivalent Se(4), and two equivalent Se(6) atoms to form SmSe6 octahedra that share corners with two equivalent Na(1)Se6 octahedra, corners with two equivalent Na(2)Se6 octahedra, corners with two equivalent Na(3)Se6 octahedra, corners with four equivalent Si(2)SiSe3 tetrahedra,  an edgeedge with one Na(5)Se6 octahedra, edges with two equivalent Na(1)Se6 octahedra, edges with two equivalent Na(2)Se6 octahedra, edges with two equivalent Na(3)Se6 octahedra, and edges with two equivalent Na(6)Se6 octahedra. The corner-sharing octahedral tilt angles range from 7-8°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted trigonal non-coplanar geometry to one Se(1), one Se(3), and one Se(5) atom. In the second Si site, Si(2) is bonded to one Si(2), one Se(2), one Se(4), and one Se(6) atom to form distorted SiSiSe3 tetrahedra that share  a cornercorner with one Na(1)Se6 octahedra,  a cornercorner with one Na(2)Se6 octahedra,  a cornercorner with one Na(3)Se6 octahedra,  a cornercorner with one Na(4)Se6 octahedra,  a cornercorner with one Na(6)Se6 octahedra,  a cornercorner with one Se(4)Na4SmSi octahedra,  a cornercorner with one Se(6)Na4SmSi octahedra,  a cornercorner with one Se(2)Na5Si octahedra, corners with two equivalent Na(5)Se6 octahedra, corners with two equivalent Sm(1)Se6 octahedra,  an edgeedge with one Na(1)Se6 octahedra,  an edgeedge with one Na(2)Se6 octahedra, and  an edgeedge with one Na(3)Se6 octahedra. The corner-sharing octahedral tilt angles range from 18-78°. There are six inequivalent Se sites. In the first Se site, Se(5) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), one Na(6), and one Si(1) atom to form SeNa5Si octahedra that share  a cornercorner with one Se(4)Na4SmSi octahedra,  a cornercorner with one Se(6)Na4SmSi octahedra,  a cornercorner with one Se(2)Na5Si octahedra, corners with two equivalent Se(1)Na4SmSi octahedra, corners with two equivalent Se(3)Na5Si octahedra,  an edgeedge with one Se(6)Na4SmSi octahedra,  an edgeedge with one Se(5)Na5Si octahedra, edges with two equivalent Se(1)Na4SmSi octahedra, edges with two equivalent Se(4)Na4SmSi octahedra, edges with two equivalent Se(2)Na5Si octahedra, and edges with two equivalent Se(3)Na5Si octahedra. The corner-sharing octahedral tilt angles range from 3-89°. In the second Se site, Se(6) is bonded to one Na(1), one Na(2), one Na(3), one Na(5), one Sm(1), and one Si(2) atom to form distorted SeNa4SmSi octahedra that share  a cornercorner with one Se(1)Na4SmSi octahedra,  a cornercorner with one Se(3)Na5Si octahedra,  a cornercorner with one Se(5)Na5Si octahedra, corners with two equivalent Se(4)Na4SmSi octahedra, corners with two equivalent Se(2)Na5Si octahedra,  a cornercorner with one Si(2)SiSe3 tetrahedra,  an edgeedge with one Se(6)Na4SmSi octahedra,  an edgeedge with one Se(5)Na5Si octahedra, edges with two equivalent Se(1)Na4SmSi octahedra, edges with two equivalent Se(4)Na4SmSi octahedra, edges with two equivalent Se(2)Na5Si octahedra, and edges with two equivalent Se(3)Na5Si octahedra. The corner-sharing octahedral tilt angles range from 3-92°. In the third Se site, Se(1) is bonded to one Na(1), one Na(2), one Na(3), one Na(6), one Sm(1), and one Si(1) atom to form SeNa4SmSi octahedra that share  a cornercorner with one Se(4)Na4SmSi octahedra,  a cornercorner with one Se(6)Na4SmSi octahedra,  a cornercorner with one Se(2)Na5Si octahedra, corners with two equivalent Se(1)Na4SmSi octahedra, corners with two equivalent Se(5)Na5Si octahedra,  an edgeedge with one Se(2)Na5Si octahedra, edges with two equivalent Se(6)Na4SmSi octahedra, edges with two equivalent Se(3)Na5Si octahedra, edges with two equivalent Se(5)Na5Si octahedra, and edges with three equivalent Se(4)Na4SmSi octahedra. The corner-sharing octahedral tilt angles range from 1-91°. In the fourth Se site, Se(2) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), one Na(5), and one Si(2) atom to form SeNa5Si octahedra that share  a cornercorner with one Se(1)Na4SmSi octahedra,  a cornercorner with one Se(3)Na5Si octahedra,  a cornercorner with one Se(5)Na5Si octahedra, corners with two equivalent Se(6)Na4SmSi octahedra, corners with two equivalent Se(2)Na5Si octahedra,  a cornercorner with one Si(2)SiSe3 tetrahedra,  an edgeedge with one Se(1)Na4SmSi octahedra, edges with two equivalent Se(4)Na4SmSi octahedra, edges with two equivalent Se(6)Na4SmSi octahedra, edges with two equivalent Se(5)Na5Si octahedra, and edges with three equivalent Se(3)Na5Si octahedra. The corner-sharing octahedral tilt angles range from 1-92°. In the fifth Se site, Se(3) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), one Na(5), and one Si(1) atom to form SeNa5Si octahedra that share  a cornercorner with one Se(4)Na4SmSi octahedra,  a cornercorner with one Se(6)Na4SmSi octahedra,  a cornercorner with one Se(2)Na5Si octahedra, corners with two equivalent Se(3)Na5Si octahedra, corners with two equivalent Se(5)Na5Si octahedra,  an edgeedge with one Se(4)Na4SmSi octahedra, edges with two equivalent Se(1)Na4SmSi octahedra, edges with two equivalent Se(6)Na4SmSi octahedra, edges with two equivalent Se(5)Na5Si octahedra, and edges with three equivalent Se(2)Na5Si octahedra. The corner-sharing octahedral tilt angles range from 1-89°. In the sixth Se site, Se(4) is bonded to one Na(1), one Na(2), one Na(3), one Na(6), one Sm(1), and one Si(2) atom to form distorted SeNa4SmSi octahedra that share  a cornercorner with one Se(1)Na4SmSi octahedra,  a cornercorner with one Se(3)Na5Si octahedra,  a cornercorner with one Se(5)Na5Si octahedra, corners with two equivalent Se(4)Na4SmSi octahedra, corners with two equivalent Se(6)Na4SmSi octahedra,  a cornercorner with one Si(2)SiSe3 tetrahedra,  an edgeedge with one Se(3)Na5Si octahedra, edges with two equivalent Se(6)Na4SmSi octahedra, edges with two equivalent Se(2)Na5Si octahedra, edges with two equivalent Se(5)Na5Si octahedra, and edges with three equivalent Se(1)Na4SmSi octahedra. The corner-sharing octahedral tilt angles range from 3-93°.
Na9Sm(SiSe3)4 crystallizes in the monoclinic C2 space group. There are six inequivalent Na sites. In the first Na site, Na(1) is bonded to one Se(1), one Se(2), one Se(3), one Se(4), one Se(5), and one Se(6) atom to form NaSe6 octahedra that share  a cornercorner with one Na(4)Se6 octahedra,  a cornercorner with one Na(5)Se6 octahedra,  a cornercorner with one Na(6)Se6 octahedra,  a cornercorner with one Sm(1)Se6 octahedra,  a cornercorner with one Si(2)SiSe3 tetrahedra,  an edgeedge with one Na(4)Se6 octahedra,  an edgeedge with one Na(5)Se6 octahedra,  an edgeedge with one Na(6)Se6 octahedra,  an edgeedge with one Sm(1)Se6 octahedra, edges with three equivalent Na(2)Se6 octahedra, edges with three equivalent Na(3)Se6 octahedra, and  an edgeedge with one Si(2)SiSe3 tetrahedra. The corner-sharing octahedral tilt angles range from 5-8°. The Na(1)-Se(1) bond length is 3.10 Å. The Na(1)-Se(2) bond length is 2.99 Å. The Na(1)-Se(3) bond length is 2.94 Å. The Na(1)-Se(4) bond length is 3.04 Å. The Na(1)-Se(5) bond length is 3.13 Å. The Na(1)-Se(6) bond length is 3.26 Å. In the second Na site, Na(2) is bonded to one Se(1), one Se(2), one Se(3), one Se(4), one Se(5), and one Se(6) atom to form NaSe6 octahedra that share  a cornercorner with one Na(4)Se6 octahedra,  a cornercorner with one Na(5)Se6 octahedra,  a cornercorner with one Na(6)Se6 octahedra,  a cornercorner with one Sm(1)Se6 octahedra,  a cornercorner with one Si(2)SiSe3 tetrahedra,  an edgeedge with one Na(4)Se6 octahedra,  an edgeedge with one Na(5)Se6 octahedra,  an edgeedge with one Na(6)Se6 octahedra,  an edgeedge with one Sm(1)Se6 octahedra, edges with three equivalent Na(1)Se6 octahedra, edges with three equivalent Na(3)Se6 octahedra, and  an edgeedge with one Si(2)SiSe3 tetrahedra. The corner-sharing octahedral tilt angles range from 6-9°. The Na(2)-Se(1) bond length is 3.01 Å. The Na(2)-Se(2) bond length is 2.96 Å. The Na(2)-Se(3) bond length is 3.11 Å. The Na(2)-Se(4) bond length is 3.15 Å. The Na(2)-Se(5) bond length is 3.02 Å. The Na(2)-Se(6) bond length is 3.17 Å. In the third Na site, Na(3) is bonded to one Se(1), one Se(2), one Se(3), one Se(4), one Se(5), and one Se(6) atom to form NaSe6 octahedra that share  a cornercorner with one Na(4)Se6 octahedra,  a cornercorner with one Na(5)Se6 octahedra,  a cornercorner with one Na(6)Se6 octahedra,  a cornercorner with one Sm(1)Se6 octahedra,  a cornercorner with one Si(2)SiSe3 tetrahedra,  an edgeedge with one Na(4)Se6 octahedra,  an edgeedge with one Na(5)Se6 octahedra,  an edgeedge with one Na(6)Se6 octahedra,  an edgeedge with one Sm(1)Se6 octahedra, edges with three equivalent Na(1)Se6 octahedra, edges with three equivalent Na(2)Se6 octahedra, and  an edgeedge with one Si(2)SiSe3 tetrahedra. The corner-sharing octahedral tilt angles range from 7-8°. The Na(3)-Se(1) bond length is 3.18 Å. The Na(3)-Se(2) bond length is 3.08 Å. The Na(3)-Se(3) bond length is 2.97 Å. The Na(3)-Se(4) bond length is 3.15 Å. The Na(3)-Se(5) bond length is 3.01 Å. The Na(3)-Se(6) bond length is 3.06 Å. In the fourth Na site, Na(4) is bonded to two equivalent Se(2), two equivalent Se(3), and two equivalent Se(5) atoms to form NaSe6 octahedra that share corners with two equivalent Na(1)Se6 octahedra, corners with two equivalent Na(2)Se6 octahedra, corners with two equivalent Na(3)Se6 octahedra, corners with two equivalent Si(2)SiSe3 tetrahedra,  an edgeedge with one Na(6)Se6 octahedra, edges with two equivalent Na(1)Se6 octahedra, edges with two equivalent Na(2)Se6 octahedra, edges with two equivalent Na(3)Se6 octahedra, and edges with two equivalent Na(5)Se6 octahedra. The corner-sharing octahedral tilt angles range from 6-8°. Both Na(4)-Se(2) bond lengths are 3.11 Å. Both Na(4)-Se(3) bond lengths are 3.09 Å. Both Na(4)-Se(5) bond lengths are 3.09 Å. In the fifth Na site, Na(5) is bonded to two equivalent Se(2), two equivalent Se(3), and two equivalent Se(6) atoms to form NaSe6 octahedra that share corners with two equivalent Na(1)Se6 octahedra, corners with two equivalent Na(2)Se6 octahedra, corners with two equivalent Na(3)Se6 octahedra, corners with four equivalent Si(2)SiSe3 tetrahedra,  an edgeedge with one Sm(1)Se6 octahedra, edges with two equivalent Na(1)Se6 octahedra, edges with two equivalent Na(2)Se6 octahedra, edges with two equivalent Na(3)Se6 octahedra, and edges with two equivalent Na(4)Se6 octahedra. The corner-sharing octahedral tilt angles range from 5-9°. Both Na(5)-Se(2) bond lengths are 3.12 Å. Both Na(5)-Se(3) bond lengths are 3.08 Å. Both Na(5)-Se(6) bond lengths are 3.15 Å. In the sixth Na site, Na(6) is bonded to two equivalent Se(1), two equivalent Se(4), and two equivalent Se(5) atoms to form NaSe6 octahedra that share corners with two equivalent Na(1)Se6 octahedra, corners with two equivalent Na(2)Se6 octahedra, corners with two equivalent Na(3)Se6 octahedra, corners with two equivalent Si(2)SiSe3 tetrahedra,  an edgeedge with one Na(4)Se6 octahedra, edges with two equivalent Na(1)Se6 octahedra, edges with two equivalent Na(2)Se6 octahedra, edges with two equivalent Na(3)Se6 octahedra, and edges with two equivalent Sm(1)Se6 octahedra. The corner-sharing octahedral tilt angles range from 7-8°. Both Na(6)-Se(1) bond lengths are 3.09 Å. Both Na(6)-Se(4) bond lengths are 3.11 Å. Both Na(6)-Se(5) bond lengths are 3.03 Å. Sm(1) is bonded to two equivalent Se(1), two equivalent Se(4), and two equivalent Se(6) atoms to form SmSe6 octahedra that share corners with two equivalent Na(1)Se6 octahedra, corners with two equivalent Na(2)Se6 octahedra, corners with two equivalent Na(3)Se6 octahedra, corners with four equivalent Si(2)SiSe3 tetrahedra,  an edgeedge with one Na(5)Se6 octahedra, edges with two equivalent Na(1)Se6 octahedra, edges with two equivalent Na(2)Se6 octahedra, edges with two equivalent Na(3)Se6 octahedra, and edges with two equivalent Na(6)Se6 octahedra. The corner-sharing octahedral tilt angles range from 7-8°. Both Sm(1)-Se(1) bond lengths are 2.95 Å. Both Sm(1)-Se(4) bond lengths are 2.98 Å. Both Sm(1)-Se(6) bond lengths are 2.97 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted trigonal non-coplanar geometry to one Se(1), one Se(3), and one Se(5) atom. The Si(1)-Se(1) bond length is 2.36 Å. The Si(1)-Se(3) bond length is 2.29 Å. The Si(1)-Se(5) bond length is 2.28 Å. In the second Si site, Si(2) is bonded to one Si(2), one Se(2), one Se(4), and one Se(6) atom to form distorted SiSiSe3 tetrahedra that share  a cornercorner with one Na(1)Se6 octahedra,  a cornercorner with one Na(2)Se6 octahedra,  a cornercorner with one Na(3)Se6 octahedra,  a cornercorner with one Na(4)Se6 octahedra,  a cornercorner with one Na(6)Se6 octahedra,  a cornercorner with one Se(4)Na4SmSi octahedra,  a cornercorner with one Se(6)Na4SmSi octahedra,  a cornercorner with one Se(2)Na5Si octahedra, corners with two equivalent Na(5)Se6 octahedra, corners with two equivalent Sm(1)Se6 octahedra,  an edgeedge with one Na(1)Se6 octahedra,  an edgeedge with one Na(2)Se6 octahedra, and  an edgeedge with one Na(3)Se6 octahedra. The corner-sharing octahedral tilt angles range from 18-78°. The Si(2)-Si(2) bond length is 2.32 Å. The Si(2)-Se(2) bond length is 2.27 Å. The Si(2)-Se(4) bond length is 2.33 Å. The Si(2)-Se(6) bond length is 2.32 Å. There are six inequivalent Se sites. In the first Se site, Se(5) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), one Na(6), and one Si(1) atom to form SeNa5Si octahedra that share  a cornercorner with one Se(4)Na4SmSi octahedra,  a cornercorner with one Se(6)Na4SmSi octahedra,  a cornercorner with one Se(2)Na5Si octahedra, corners with two equivalent Se(1)Na4SmSi octahedra, corners with two equivalent Se(3)Na5Si octahedra,  an edgeedge with one Se(6)Na4SmSi octahedra,  an edgeedge with one Se(5)Na5Si octahedra, edges with two equivalent Se(1)Na4SmSi octahedra, edges with two equivalent Se(4)Na4SmSi octahedra, edges with two equivalent Se(2)Na5Si octahedra, and edges with two equivalent Se(3)Na5Si octahedra. The corner-sharing octahedral tilt angles range from 3-89°. In the second Se site, Se(6) is bonded to one Na(1), one Na(2), one Na(3), one Na(5), one Sm(1), and one Si(2) atom to form distorted SeNa4SmSi octahedra that share  a cornercorner with one Se(1)Na4SmSi octahedra,  a cornercorner with one Se(3)Na5Si octahedra,  a cornercorner with one Se(5)Na5Si octahedra, corners with two equivalent Se(4)Na4SmSi octahedra, corners with two equivalent Se(2)Na5Si octahedra,  a cornercorner with one Si(2)SiSe3 tetrahedra,  an edgeedge with one Se(6)Na4SmSi octahedra,  an edgeedge with one Se(5)Na5Si octahedra, edges with two equivalent Se(1)Na4SmSi octahedra, edges with two equivalent Se(4)Na4SmSi octahedra, edges with two equivalent Se(2)Na5Si octahedra, and edges with two equivalent Se(3)Na5Si octahedra. The corner-sharing octahedral tilt angles range from 3-92°. In the third Se site, Se(1) is bonded to one Na(1), one Na(2), one Na(3), one Na(6), one Sm(1), and one Si(1) atom to form SeNa4SmSi octahedra that share  a cornercorner with one Se(4)Na4SmSi octahedra,  a cornercorner with one Se(6)Na4SmSi octahedra,  a cornercorner with one Se(2)Na5Si octahedra, corners with two equivalent Se(1)Na4SmSi octahedra, corners with two equivalent Se(5)Na5Si octahedra,  an edgeedge with one Se(2)Na5Si octahedra, edges with two equivalent Se(6)Na4SmSi octahedra, edges with two equivalent Se(3)Na5Si octahedra, edges with two equivalent Se(5)Na5Si octahedra, and edges with three equivalent Se(4)Na4SmSi octahedra. The corner-sharing octahedral tilt angles range from 1-91°. In the fourth Se site, Se(2) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), one Na(5), and one Si(2) atom to form SeNa5Si octahedra that share  a cornercorner with one Se(1)Na4SmSi octahedra,  a cornercorner with one Se(3)Na5Si octahedra,  a cornercorner with one Se(5)Na5Si octahedra, corners with two equivalent Se(6)Na4SmSi octahedra, corners with two equivalent Se(2)Na5Si octahedra,  a cornercorner with one Si(2)SiSe3 tetrahedra,  an edgeedge with one Se(1)Na4SmSi octahedra, edges with two equivalent Se(4)Na4SmSi octahedra, edges with two equivalent Se(6)Na4SmSi octahedra, edges with two equivalent Se(5)Na5Si octahedra, and edges with three equivalent Se(3)Na5Si octahedra. The corner-sharing octahedral tilt angles range from 1-92°. In the fifth Se site, Se(3) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), one Na(5), and one Si(1) atom to form SeNa5Si octahedra that share  a cornercorner with one Se(4)Na4SmSi octahedra,  a cornercorner with one Se(6)Na4SmSi octahedra,  a cornercorner with one Se(2)Na5Si octahedra, corners with two equivalent Se(3)Na5Si octahedra, corners with two equivalent Se(5)Na5Si octahedra,  an edgeedge with one Se(4)Na4SmSi octahedra, edges with two equivalent Se(1)Na4SmSi octahedra, edges with two equivalent Se(6)Na4SmSi octahedra, edges with two equivalent Se(5)Na5Si octahedra, and edges with three equivalent Se(2)Na5Si octahedra. The corner-sharing octahedral tilt angles range from 1-89°. In the sixth Se site, Se(4) is bonded to one Na(1), one Na(2), one Na(3), one Na(6), one Sm(1), and one Si(2) atom to form distorted SeNa4SmSi octahedra that share  a cornercorner with one Se(1)Na4SmSi octahedra,  a cornercorner with one Se(3)Na5Si octahedra,  a cornercorner with one Se(5)Na5Si octahedra, corners with two equivalent Se(4)Na4SmSi octahedra, corners with two equivalent Se(6)Na4SmSi octahedra,  a cornercorner with one Si(2)SiSe3 tetrahedra,  an edgeedge with one Se(3)Na5Si octahedra, edges with two equivalent Se(6)Na4SmSi octahedra, edges with two equivalent Se(2)Na5Si octahedra, edges with two equivalent Se(5)Na5Si octahedra, and edges with three equivalent Se(1)Na4SmSi octahedra. The corner-sharing octahedral tilt angles range from 3-93°.