Na7In3Se8 crystallizes in the triclinic P-1 space group. There are seven inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one Se(2), one Se(4), one Se(7), and three equivalent Se(1) atoms. In the second Na site, Na(2) is bonded to one Se(1), one Se(2), one Se(4), one Se(5), and one Se(8) atom to form distorted NaSe5 square pyramids that share corners with three equivalent Na(5)Se6 octahedra,  a cornercorner with one Na(3)Se6 square pyramid, corners with two equivalent Na(7)Se4 tetrahedra, corners with three equivalent In(1)Se4 tetrahedra, corners with three equivalent In(3)Se4 tetrahedra,  an edgeedge with one Na(4)Se6 octahedra,  an edgeedge with one Na(3)Se6 square pyramid, and  an edgeedge with one In(2)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 38-53°. In the third Na site, Na(3) is bonded to one Se(2), one Se(3), one Se(6), one Se(7), and two equivalent Se(8) atoms to form distorted NaSe6 square pyramids that share corners with two equivalent Na(5)Se6 octahedra,  a cornercorner with one Na(2)Se5 square pyramid, corners with two equivalent Na(3)Se6 square pyramids, corners with two equivalent Na(7)Se4 tetrahedra, corners with two equivalent In(1)Se4 tetrahedra, corners with two equivalent In(2)Se4 tetrahedra, edges with three equivalent Na(4)Se6 octahedra,  an edgeedge with one Na(2)Se5 square pyramid,  an edgeedge with one Na(7)Se4 tetrahedra,  an edgeedge with one In(2)Se4 tetrahedra,  an edgeedge with one In(3)Se4 tetrahedra, and  a faceface with one Na(5)Se6 octahedra. The corner-sharing octahedral tilt angles range from 38-60°. In the fourth Na site, Na(4) is bonded to one Se(5), one Se(6), one Se(8), and three equivalent Se(3) atoms to form distorted NaSe6 octahedra that share corners with two equivalent Na(4)Se6 octahedra, corners with two equivalent Na(5)Se6 octahedra,  a cornercorner with one Na(7)Se4 tetrahedra,  a cornercorner with one In(1)Se4 tetrahedra,  a cornercorner with one In(2)Se4 tetrahedra, corners with three equivalent In(3)Se4 tetrahedra, edges with two equivalent Na(4)Se6 octahedra,  an edgeedge with one Na(2)Se5 square pyramid, edges with three equivalent Na(3)Se6 square pyramids,  an edgeedge with one In(3)Se4 tetrahedra, and edges with two equivalent Na(7)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 10-59°. In the fifth Na site, Na(5) is bonded to one Se(1), one Se(4), one Se(6), one Se(8), and two equivalent Se(7) atoms to form distorted NaSe6 octahedra that share corners with two equivalent Na(4)Se6 octahedra, corners with two equivalent Na(3)Se6 square pyramids, corners with three equivalent Na(2)Se5 square pyramids,  a cornercorner with one Na(7)Se4 tetrahedra,  a cornercorner with one In(1)Se4 tetrahedra, corners with two equivalent In(2)Se4 tetrahedra,  an edgeedge with one Na(5)Se6 octahedra,  an edgeedge with one Na(7)Se4 tetrahedra,  an edgeedge with one In(1)Se4 tetrahedra, edges with two equivalent In(2)Se4 tetrahedra, and  a faceface with one Na(3)Se6 square pyramid. The corner-sharing octahedral tilt angles range from 35-59°. In the sixth Na site, Na(6) is bonded in a 6-coordinate geometry to one Se(2), one Se(3), one Se(4), one Se(6), and two equivalent Se(5) atoms. In the seventh Na site, Na(7) is bonded to one Se(3), one Se(4), one Se(6), and one Se(8) atom to form distorted NaSe4 tetrahedra that share  a cornercorner with one Na(4)Se6 octahedra,  a cornercorner with one Na(5)Se6 octahedra, corners with two equivalent Na(2)Se5 square pyramids, corners with two equivalent Na(3)Se6 square pyramids,  a cornercorner with one In(2)Se4 tetrahedra,  a cornercorner with one In(3)Se4 tetrahedra,  an edgeedge with one Na(5)Se6 octahedra, edges with two equivalent Na(4)Se6 octahedra,  an edgeedge with one Na(3)Se6 square pyramid, and  an edgeedge with one In(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-77°. There are three inequivalent In sites. In the first In site, In(1) is bonded to one Se(1), one Se(2), one Se(4), and one Se(6) atom to form InSe4 tetrahedra that share  a cornercorner with one Na(4)Se6 octahedra,  a cornercorner with one Na(5)Se6 octahedra, corners with two equivalent Na(3)Se6 square pyramids, corners with three equivalent Na(2)Se5 square pyramids,  a cornercorner with one In(2)Se4 tetrahedra,  a cornercorner with one In(3)Se4 tetrahedra,  an edgeedge with one Na(5)Se6 octahedra, and  an edgeedge with one Na(7)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-57°. In the second In site, In(2) is bonded to one Se(1), one Se(8), and two equivalent Se(7) atoms to form InSe4 tetrahedra that share  a cornercorner with one Na(4)Se6 octahedra, corners with two equivalent Na(5)Se6 octahedra, corners with two equivalent Na(3)Se6 square pyramids,  a cornercorner with one Na(7)Se4 tetrahedra,  a cornercorner with one In(1)Se4 tetrahedra, edges with two equivalent Na(5)Se6 octahedra,  an edgeedge with one Na(2)Se5 square pyramid,  an edgeedge with one Na(3)Se6 square pyramid, and  an edgeedge with one In(2)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 21-55°. In the third In site, In(3) is bonded to one Se(2), one Se(3), and two equivalent Se(5) atoms to form InSe4 tetrahedra that share corners with three equivalent Na(4)Se6 octahedra, corners with three equivalent Na(2)Se5 square pyramids,  a cornercorner with one Na(7)Se4 tetrahedra,  a cornercorner with one In(1)Se4 tetrahedra,  an edgeedge with one Na(4)Se6 octahedra,  an edgeedge with one Na(3)Se6 square pyramid, and  an edgeedge with one In(3)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 19-66°. There are eight inequivalent Se sites. In the first Se site, Se(7) is bonded to one Na(1), one Na(3), two equivalent Na(5), and two equivalent In(2) atoms to form distorted SeNa4In2 pentagonal pyramids that share  a cornercorner with one Se(4)Na5In pentagonal pyramid,  a cornercorner with one Se(6)Na5In pentagonal pyramid,  an edgeedge with one Se(4)Na5In pentagonal pyramid,  an edgeedge with one Se(6)Na5In pentagonal pyramid, and edges with two equivalent Se(7)Na4In2 pentagonal pyramids. In the second Se site, Se(8) is bonded in a 7-coordinate geometry to one Na(2), one Na(4), one Na(5), one Na(7), two equivalent Na(3), and one In(2) atom. In the third Se site, Se(1) is bonded in a 7-coordinate geometry to one Na(2), one Na(5), three equivalent Na(1), one In(1), and one In(2) atom. In the fourth Se site, Se(2) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), one Na(3), one Na(6), one In(1), and one In(3) atom. In the fifth Se site, Se(3) is bonded in a 7-coordinate geometry to one Na(3), one Na(6), one Na(7), three equivalent Na(4), and one In(3) atom. In the sixth Se site, Se(4) is bonded to one Na(1), one Na(2), one Na(5), one Na(6), one Na(7), and one In(1) atom to form distorted SeNa5In pentagonal pyramids that share  a cornercorner with one Se(5)Na4In2 pentagonal pyramid,  a cornercorner with one Se(7)Na4In2 pentagonal pyramid,  an edgeedge with one Se(5)Na4In2 pentagonal pyramid,  an edgeedge with one Se(7)Na4In2 pentagonal pyramid, and edges with two equivalent Se(6)Na5In pentagonal pyramids. In the seventh Se site, Se(5) is bonded to one Na(2), one Na(4), two equivalent Na(6), and two equivalent In(3) atoms to form distorted SeNa4In2 pentagonal pyramids that share  a cornercorner with one Se(4)Na5In pentagonal pyramid,  a cornercorner with one Se(6)Na5In pentagonal pyramid,  an edgeedge with one Se(4)Na5In pentagonal pyramid,  an edgeedge with one Se(6)Na5In pentagonal pyramid, and edges with two equivalent Se(5)Na4In2 pentagonal pyramids. In the eighth Se site, Se(6) is bonded to one Na(3), one Na(4), one Na(5), one Na(6), one Na(7), and one In(1) atom to form distorted SeNa5In pentagonal pyramids that share  a cornercorner with one Se(5)Na4In2 pentagonal pyramid,  a cornercorner with one Se(7)Na4In2 pentagonal pyramid,  an edgeedge with one Se(5)Na4In2 pentagonal pyramid,  an edgeedge with one Se(7)Na4In2 pentagonal pyramid, and edges with two equivalent Se(4)Na5In pentagonal pyramids.
Na7In3Se8 crystallizes in the triclinic P-1 space group. There are seven inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one Se(2), one Se(4), one Se(7), and three equivalent Se(1) atoms. The Na(1)-Se(2) bond length is 3.12 Å. The Na(1)-Se(4) bond length is 2.85 Å. The Na(1)-Se(7) bond length is 3.07 Å. There are a spread of Na(1)-Se(1) bond distances ranging from 3.10-3.48 Å. In the second Na site, Na(2) is bonded to one Se(1), one Se(2), one Se(4), one Se(5), and one Se(8) atom to form distorted NaSe5 square pyramids that share corners with three equivalent Na(5)Se6 octahedra,  a cornercorner with one Na(3)Se6 square pyramid, corners with two equivalent Na(7)Se4 tetrahedra, corners with three equivalent In(1)Se4 tetrahedra, corners with three equivalent In(3)Se4 tetrahedra,  an edgeedge with one Na(4)Se6 octahedra,  an edgeedge with one Na(3)Se6 square pyramid, and  an edgeedge with one In(2)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 38-53°. The Na(2)-Se(1) bond length is 3.23 Å. The Na(2)-Se(2) bond length is 3.16 Å. The Na(2)-Se(4) bond length is 2.85 Å. The Na(2)-Se(5) bond length is 3.08 Å. The Na(2)-Se(8) bond length is 2.91 Å. In the third Na site, Na(3) is bonded to one Se(2), one Se(3), one Se(6), one Se(7), and two equivalent Se(8) atoms to form distorted NaSe6 square pyramids that share corners with two equivalent Na(5)Se6 octahedra,  a cornercorner with one Na(2)Se5 square pyramid, corners with two equivalent Na(3)Se6 square pyramids, corners with two equivalent Na(7)Se4 tetrahedra, corners with two equivalent In(1)Se4 tetrahedra, corners with two equivalent In(2)Se4 tetrahedra, edges with three equivalent Na(4)Se6 octahedra,  an edgeedge with one Na(2)Se5 square pyramid,  an edgeedge with one Na(7)Se4 tetrahedra,  an edgeedge with one In(2)Se4 tetrahedra,  an edgeedge with one In(3)Se4 tetrahedra, and  a faceface with one Na(5)Se6 octahedra. The corner-sharing octahedral tilt angles range from 38-60°. The Na(3)-Se(2) bond length is 3.28 Å. The Na(3)-Se(3) bond length is 2.90 Å. The Na(3)-Se(6) bond length is 2.94 Å. The Na(3)-Se(7) bond length is 2.98 Å. There is one shorter (3.16 Å) and one longer (3.57 Å) Na(3)-Se(8) bond length. In the fourth Na site, Na(4) is bonded to one Se(5), one Se(6), one Se(8), and three equivalent Se(3) atoms to form distorted NaSe6 octahedra that share corners with two equivalent Na(4)Se6 octahedra, corners with two equivalent Na(5)Se6 octahedra,  a cornercorner with one Na(7)Se4 tetrahedra,  a cornercorner with one In(1)Se4 tetrahedra,  a cornercorner with one In(2)Se4 tetrahedra, corners with three equivalent In(3)Se4 tetrahedra, edges with two equivalent Na(4)Se6 octahedra,  an edgeedge with one Na(2)Se5 square pyramid, edges with three equivalent Na(3)Se6 square pyramids,  an edgeedge with one In(3)Se4 tetrahedra, and edges with two equivalent Na(7)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 10-59°. The Na(4)-Se(5) bond length is 2.99 Å. The Na(4)-Se(6) bond length is 2.93 Å. The Na(4)-Se(8) bond length is 3.22 Å. There are a spread of Na(4)-Se(3) bond distances ranging from 3.29-3.42 Å. In the fifth Na site, Na(5) is bonded to one Se(1), one Se(4), one Se(6), one Se(8), and two equivalent Se(7) atoms to form distorted NaSe6 octahedra that share corners with two equivalent Na(4)Se6 octahedra, corners with two equivalent Na(3)Se6 square pyramids, corners with three equivalent Na(2)Se5 square pyramids,  a cornercorner with one Na(7)Se4 tetrahedra,  a cornercorner with one In(1)Se4 tetrahedra, corners with two equivalent In(2)Se4 tetrahedra,  an edgeedge with one Na(5)Se6 octahedra,  an edgeedge with one Na(7)Se4 tetrahedra,  an edgeedge with one In(1)Se4 tetrahedra, edges with two equivalent In(2)Se4 tetrahedra, and  a faceface with one Na(3)Se6 square pyramid. The corner-sharing octahedral tilt angles range from 35-59°. The Na(5)-Se(1) bond length is 3.23 Å. The Na(5)-Se(4) bond length is 2.90 Å. The Na(5)-Se(6) bond length is 2.87 Å. The Na(5)-Se(8) bond length is 3.20 Å. There is one shorter (2.94 Å) and one longer (3.06 Å) Na(5)-Se(7) bond length. In the sixth Na site, Na(6) is bonded in a 6-coordinate geometry to one Se(2), one Se(3), one Se(4), one Se(6), and two equivalent Se(5) atoms. The Na(6)-Se(2) bond length is 3.34 Å. The Na(6)-Se(3) bond length is 3.17 Å. The Na(6)-Se(4) bond length is 2.91 Å. The Na(6)-Se(6) bond length is 2.85 Å. There is one shorter (2.95 Å) and one longer (3.04 Å) Na(6)-Se(5) bond length. In the seventh Na site, Na(7) is bonded to one Se(3), one Se(4), one Se(6), and one Se(8) atom to form distorted NaSe4 tetrahedra that share  a cornercorner with one Na(4)Se6 octahedra,  a cornercorner with one Na(5)Se6 octahedra, corners with two equivalent Na(2)Se5 square pyramids, corners with two equivalent Na(3)Se6 square pyramids,  a cornercorner with one In(2)Se4 tetrahedra,  a cornercorner with one In(3)Se4 tetrahedra,  an edgeedge with one Na(5)Se6 octahedra, edges with two equivalent Na(4)Se6 octahedra,  an edgeedge with one Na(3)Se6 square pyramid, and  an edgeedge with one In(1)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-77°. The Na(7)-Se(3) bond length is 2.86 Å. The Na(7)-Se(4) bond length is 2.89 Å. The Na(7)-Se(6) bond length is 2.85 Å. The Na(7)-Se(8) bond length is 2.86 Å. There are three inequivalent In sites. In the first In site, In(1) is bonded to one Se(1), one Se(2), one Se(4), and one Se(6) atom to form InSe4 tetrahedra that share  a cornercorner with one Na(4)Se6 octahedra,  a cornercorner with one Na(5)Se6 octahedra, corners with two equivalent Na(3)Se6 square pyramids, corners with three equivalent Na(2)Se5 square pyramids,  a cornercorner with one In(2)Se4 tetrahedra,  a cornercorner with one In(3)Se4 tetrahedra,  an edgeedge with one Na(5)Se6 octahedra, and  an edgeedge with one Na(7)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-57°. The In(1)-Se(1) bond length is 2.67 Å. The In(1)-Se(2) bond length is 2.66 Å. The In(1)-Se(4) bond length is 2.54 Å. The In(1)-Se(6) bond length is 2.56 Å. In the second In site, In(2) is bonded to one Se(1), one Se(8), and two equivalent Se(7) atoms to form InSe4 tetrahedra that share  a cornercorner with one Na(4)Se6 octahedra, corners with two equivalent Na(5)Se6 octahedra, corners with two equivalent Na(3)Se6 square pyramids,  a cornercorner with one Na(7)Se4 tetrahedra,  a cornercorner with one In(1)Se4 tetrahedra, edges with two equivalent Na(5)Se6 octahedra,  an edgeedge with one Na(2)Se5 square pyramid,  an edgeedge with one Na(3)Se6 square pyramid, and  an edgeedge with one In(2)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 21-55°. The In(2)-Se(1) bond length is 2.62 Å. The In(2)-Se(8) bond length is 2.55 Å. There is one shorter (2.63 Å) and one longer (2.65 Å) In(2)-Se(7) bond length. In the third In site, In(3) is bonded to one Se(2), one Se(3), and two equivalent Se(5) atoms to form InSe4 tetrahedra that share corners with three equivalent Na(4)Se6 octahedra, corners with three equivalent Na(2)Se5 square pyramids,  a cornercorner with one Na(7)Se4 tetrahedra,  a cornercorner with one In(1)Se4 tetrahedra,  an edgeedge with one Na(4)Se6 octahedra,  an edgeedge with one Na(3)Se6 square pyramid, and  an edgeedge with one In(3)Se4 tetrahedra. The corner-sharing octahedral tilt angles range from 19-66°. The In(3)-Se(2) bond length is 2.63 Å. The In(3)-Se(3) bond length is 2.55 Å. There is one shorter (2.63 Å) and one longer (2.65 Å) In(3)-Se(5) bond length. There are eight inequivalent Se sites. In the first Se site, Se(7) is bonded to one Na(1), one Na(3), two equivalent Na(5), and two equivalent In(2) atoms to form distorted SeNa4In2 pentagonal pyramids that share  a cornercorner with one Se(4)Na5In pentagonal pyramid,  a cornercorner with one Se(6)Na5In pentagonal pyramid,  an edgeedge with one Se(4)Na5In pentagonal pyramid,  an edgeedge with one Se(6)Na5In pentagonal pyramid, and edges with two equivalent Se(7)Na4In2 pentagonal pyramids. In the second Se site, Se(8) is bonded in a 7-coordinate geometry to one Na(2), one Na(4), one Na(5), one Na(7), two equivalent Na(3), and one In(2) atom. In the third Se site, Se(1) is bonded in a 7-coordinate geometry to one Na(2), one Na(5), three equivalent Na(1), one In(1), and one In(2) atom. In the fourth Se site, Se(2) is bonded in a 6-coordinate geometry to one Na(1), one Na(2), one Na(3), one Na(6), one In(1), and one In(3) atom. In the fifth Se site, Se(3) is bonded in a 7-coordinate geometry to one Na(3), one Na(6), one Na(7), three equivalent Na(4), and one In(3) atom. In the sixth Se site, Se(4) is bonded to one Na(1), one Na(2), one Na(5), one Na(6), one Na(7), and one In(1) atom to form distorted SeNa5In pentagonal pyramids that share  a cornercorner with one Se(5)Na4In2 pentagonal pyramid,  a cornercorner with one Se(7)Na4In2 pentagonal pyramid,  an edgeedge with one Se(5)Na4In2 pentagonal pyramid,  an edgeedge with one Se(7)Na4In2 pentagonal pyramid, and edges with two equivalent Se(6)Na5In pentagonal pyramids. In the seventh Se site, Se(5) is bonded to one Na(2), one Na(4), two equivalent Na(6), and two equivalent In(3) atoms to form distorted SeNa4In2 pentagonal pyramids that share  a cornercorner with one Se(4)Na5In pentagonal pyramid,  a cornercorner with one Se(6)Na5In pentagonal pyramid,  an edgeedge with one Se(4)Na5In pentagonal pyramid,  an edgeedge with one Se(6)Na5In pentagonal pyramid, and edges with two equivalent Se(5)Na4In2 pentagonal pyramids. In the eighth Se site, Se(6) is bonded to one Na(3), one Na(4), one Na(5), one Na(6), one Na(7), and one In(1) atom to form distorted SeNa5In pentagonal pyramids that share  a cornercorner with one Se(5)Na4In2 pentagonal pyramid,  a cornercorner with one Se(7)Na4In2 pentagonal pyramid,  an edgeedge with one Se(5)Na4In2 pentagonal pyramid,  an edgeedge with one Se(7)Na4In2 pentagonal pyramid, and edges with two equivalent Se(4)Na5In pentagonal pyramids.