Na4Ge2Se5 crystallizes in the triclinic P-1 space group. There are five inequivalent Na sites. In the first Na site, Na(1) is bonded to one Se(1), one Se(5), two equivalent Se(3), and two equivalent Se(4) atoms to form a mixture of corner and edge-sharing NaSe6 octahedra. The corner-sharing octahedral tilt angles range from 5-13°. In the second Na site, Na(2) is bonded to one Se(1), one Se(2), one Se(4), one Se(5), and two equivalent Se(3) atoms to form a mixture of distorted corner and edge-sharing NaSe6 octahedra. The corner-sharing octahedral tilt angles range from 4-13°. In the third Na site, Na(3) is bonded to two equivalent Se(3), two equivalent Se(4), and two equivalent Se(5) atoms to form a mixture of corner and edge-sharing NaSe6 octahedra. The corner-sharing octahedral tilt angles range from 3-9°. In the fourth Na site, Na(4) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(5) atoms to form a mixture of corner and edge-sharing NaSe6 octahedra. The corner-sharing octahedral tilt angles range from 3-4°. In the fifth Na site, Na(5) is bonded to one Se(4), one Se(5), two equivalent Se(1), and two equivalent Se(2) atoms to form a mixture of distorted corner and edge-sharing NaSe6 octahedra. The corner-sharing octahedral tilt angles range from 4-8°. There are two inequivalent Ge sites. In the first Ge site, Ge(1) is bonded in a distorted trigonal non-coplanar geometry to one Se(2), one Se(3), and one Se(5) atom. In the second Ge site, Ge(2) is bonded in a distorted trigonal non-coplanar geometry to one Se(1), one Se(2), and one Se(4) atom. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded to one Na(1), one Na(2), one Na(4), two equivalent Na(5), and one Ge(2) atom to form SeNa5Ge octahedra that share  a cornercorner with one Se(1)Na5Ge octahedra, corners with two equivalent Se(2)Na4Ge2 octahedra, corners with two equivalent Se(3)Na5Ge octahedra, corners with two equivalent Se(4)Na5Ge octahedra,  an edgeedge with one Se(1)Na5Ge octahedra,  an edgeedge with one Se(3)Na5Ge octahedra, edges with two equivalent Se(4)Na5Ge octahedra, edges with three equivalent Se(2)Na4Ge2 octahedra, and edges with three equivalent Se(5)Na5Ge octahedra. The corner-sharing octahedral tilt angles range from 0-89°. In the second Se site, Se(2) is bonded to one Na(2), one Na(4), two equivalent Na(5), one Ge(1), and one Ge(2) atom to form SeNa4Ge2 octahedra that share  a cornercorner with one Se(2)Na4Ge2 octahedra,  a cornercorner with one Se(3)Na5Ge octahedra, corners with two equivalent Se(1)Na5Ge octahedra, corners with two equivalent Se(5)Na5Ge octahedra,  an edgeedge with one Se(2)Na4Ge2 octahedra,  an edgeedge with one Se(3)Na5Ge octahedra, edges with two equivalent Se(4)Na5Ge octahedra, edges with two equivalent Se(5)Na5Ge octahedra, and edges with three equivalent Se(1)Na5Ge octahedra. The corner-sharing octahedral tilt angles range from 0-85°. In the third Se site, Se(3) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Ge(1) atom to form SeNa5Ge octahedra that share  a cornercorner with one Se(2)Na4Ge2 octahedra,  a cornercorner with one Se(3)Na5Ge octahedra,  a cornercorner with one Se(5)Na5Ge octahedra, corners with two equivalent Se(1)Na5Ge octahedra, corners with two equivalent Se(4)Na5Ge octahedra,  an edgeedge with one Se(2)Na4Ge2 octahedra,  an edgeedge with one Se(1)Na5Ge octahedra, edges with two equivalent Se(3)Na5Ge octahedra, edges with three equivalent Se(4)Na5Ge octahedra, and edges with three equivalent Se(5)Na5Ge octahedra. The corner-sharing octahedral tilt angles range from 0-89°. In the fourth Se site, Se(4) is bonded to one Na(2), one Na(3), one Na(5), two equivalent Na(1), and one Ge(2) atom to form SeNa5Ge octahedra that share  a cornercorner with one Se(4)Na5Ge octahedra, corners with two equivalent Se(1)Na5Ge octahedra, corners with two equivalent Se(3)Na5Ge octahedra, corners with two equivalent Se(5)Na5Ge octahedra,  an edgeedge with one Se(4)Na5Ge octahedra, edges with two equivalent Se(2)Na4Ge2 octahedra, edges with two equivalent Se(1)Na5Ge octahedra, edges with two equivalent Se(5)Na5Ge octahedra, and edges with three equivalent Se(3)Na5Ge octahedra. The corner-sharing octahedral tilt angles range from 0-88°. In the fifth Se site, Se(5) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), one Na(5), and one Ge(1) atom to form SeNa5Ge octahedra that share  a cornercorner with one Se(3)Na5Ge octahedra, corners with two equivalent Se(2)Na4Ge2 octahedra, corners with two equivalent Se(4)Na5Ge octahedra, corners with two equivalent Se(5)Na5Ge octahedra, edges with two equivalent Se(2)Na4Ge2 octahedra, edges with two equivalent Se(4)Na5Ge octahedra, edges with three equivalent Se(1)Na5Ge octahedra, and edges with three equivalent Se(3)Na5Ge octahedra. The corner-sharing octahedral tilt angles range from 0-88°.
Na4Ge2Se5 crystallizes in the triclinic P-1 space group. There are five inequivalent Na sites. In the first Na site, Na(1) is bonded to one Se(1), one Se(5), two equivalent Se(3), and two equivalent Se(4) atoms to form a mixture of corner and edge-sharing NaSe6 octahedra. The corner-sharing octahedral tilt angles range from 5-13°. The Na(1)-Se(1) bond length is 3.06 Å. The Na(1)-Se(5) bond length is 3.03 Å. There is one shorter (3.09 Å) and one longer (3.14 Å) Na(1)-Se(3) bond length. There is one shorter (3.07 Å) and one longer (3.16 Å) Na(1)-Se(4) bond length. In the second Na site, Na(2) is bonded to one Se(1), one Se(2), one Se(4), one Se(5), and two equivalent Se(3) atoms to form a mixture of distorted corner and edge-sharing NaSe6 octahedra. The corner-sharing octahedral tilt angles range from 4-13°. The Na(2)-Se(1) bond length is 2.96 Å. The Na(2)-Se(2) bond length is 3.22 Å. The Na(2)-Se(4) bond length is 3.00 Å. The Na(2)-Se(5) bond length is 3.16 Å. There is one shorter (2.95 Å) and one longer (2.97 Å) Na(2)-Se(3) bond length. In the third Na site, Na(3) is bonded to two equivalent Se(3), two equivalent Se(4), and two equivalent Se(5) atoms to form a mixture of corner and edge-sharing NaSe6 octahedra. The corner-sharing octahedral tilt angles range from 3-9°. Both Na(3)-Se(3) bond lengths are 3.04 Å. Both Na(3)-Se(4) bond lengths are 3.15 Å. Both Na(3)-Se(5) bond lengths are 3.00 Å. In the fourth Na site, Na(4) is bonded to two equivalent Se(1), two equivalent Se(2), and two equivalent Se(5) atoms to form a mixture of corner and edge-sharing NaSe6 octahedra. The corner-sharing octahedral tilt angles range from 3-4°. Both Na(4)-Se(1) bond lengths are 3.07 Å. Both Na(4)-Se(2) bond lengths are 3.12 Å. Both Na(4)-Se(5) bond lengths are 3.07 Å. In the fifth Na site, Na(5) is bonded to one Se(4), one Se(5), two equivalent Se(1), and two equivalent Se(2) atoms to form a mixture of distorted corner and edge-sharing NaSe6 octahedra. The corner-sharing octahedral tilt angles range from 4-8°. The Na(5)-Se(4) bond length is 2.97 Å. The Na(5)-Se(5) bond length is 2.92 Å. There is one shorter (2.96 Å) and one longer (3.01 Å) Na(5)-Se(1) bond length. There is one shorter (3.11 Å) and one longer (3.19 Å) Na(5)-Se(2) bond length. There are two inequivalent Ge sites. In the first Ge site, Ge(1) is bonded in a distorted trigonal non-coplanar geometry to one Se(2), one Se(3), and one Se(5) atom. The Ge(1)-Se(2) bond length is 2.47 Å. The Ge(1)-Se(3) bond length is 2.33 Å. The Ge(1)-Se(5) bond length is 2.33 Å. In the second Ge site, Ge(2) is bonded in a distorted trigonal non-coplanar geometry to one Se(1), one Se(2), and one Se(4) atom. The Ge(2)-Se(1) bond length is 2.33 Å. The Ge(2)-Se(2) bond length is 2.46 Å. The Ge(2)-Se(4) bond length is 2.33 Å. There are five inequivalent Se sites. In the first Se site, Se(1) is bonded to one Na(1), one Na(2), one Na(4), two equivalent Na(5), and one Ge(2) atom to form SeNa5Ge octahedra that share  a cornercorner with one Se(1)Na5Ge octahedra, corners with two equivalent Se(2)Na4Ge2 octahedra, corners with two equivalent Se(3)Na5Ge octahedra, corners with two equivalent Se(4)Na5Ge octahedra,  an edgeedge with one Se(1)Na5Ge octahedra,  an edgeedge with one Se(3)Na5Ge octahedra, edges with two equivalent Se(4)Na5Ge octahedra, edges with three equivalent Se(2)Na4Ge2 octahedra, and edges with three equivalent Se(5)Na5Ge octahedra. The corner-sharing octahedral tilt angles range from 0-89°. In the second Se site, Se(2) is bonded to one Na(2), one Na(4), two equivalent Na(5), one Ge(1), and one Ge(2) atom to form SeNa4Ge2 octahedra that share  a cornercorner with one Se(2)Na4Ge2 octahedra,  a cornercorner with one Se(3)Na5Ge octahedra, corners with two equivalent Se(1)Na5Ge octahedra, corners with two equivalent Se(5)Na5Ge octahedra,  an edgeedge with one Se(2)Na4Ge2 octahedra,  an edgeedge with one Se(3)Na5Ge octahedra, edges with two equivalent Se(4)Na5Ge octahedra, edges with two equivalent Se(5)Na5Ge octahedra, and edges with three equivalent Se(1)Na5Ge octahedra. The corner-sharing octahedral tilt angles range from 0-85°. In the third Se site, Se(3) is bonded to one Na(3), two equivalent Na(1), two equivalent Na(2), and one Ge(1) atom to form SeNa5Ge octahedra that share  a cornercorner with one Se(2)Na4Ge2 octahedra,  a cornercorner with one Se(3)Na5Ge octahedra,  a cornercorner with one Se(5)Na5Ge octahedra, corners with two equivalent Se(1)Na5Ge octahedra, corners with two equivalent Se(4)Na5Ge octahedra,  an edgeedge with one Se(2)Na4Ge2 octahedra,  an edgeedge with one Se(1)Na5Ge octahedra, edges with two equivalent Se(3)Na5Ge octahedra, edges with three equivalent Se(4)Na5Ge octahedra, and edges with three equivalent Se(5)Na5Ge octahedra. The corner-sharing octahedral tilt angles range from 0-89°. In the fourth Se site, Se(4) is bonded to one Na(2), one Na(3), one Na(5), two equivalent Na(1), and one Ge(2) atom to form SeNa5Ge octahedra that share  a cornercorner with one Se(4)Na5Ge octahedra, corners with two equivalent Se(1)Na5Ge octahedra, corners with two equivalent Se(3)Na5Ge octahedra, corners with two equivalent Se(5)Na5Ge octahedra,  an edgeedge with one Se(4)Na5Ge octahedra, edges with two equivalent Se(2)Na4Ge2 octahedra, edges with two equivalent Se(1)Na5Ge octahedra, edges with two equivalent Se(5)Na5Ge octahedra, and edges with three equivalent Se(3)Na5Ge octahedra. The corner-sharing octahedral tilt angles range from 0-88°. In the fifth Se site, Se(5) is bonded to one Na(1), one Na(2), one Na(3), one Na(4), one Na(5), and one Ge(1) atom to form SeNa5Ge octahedra that share  a cornercorner with one Se(3)Na5Ge octahedra, corners with two equivalent Se(2)Na4Ge2 octahedra, corners with two equivalent Se(4)Na5Ge octahedra, corners with two equivalent Se(5)Na5Ge octahedra, edges with two equivalent Se(2)Na4Ge2 octahedra, edges with two equivalent Se(4)Na5Ge octahedra, edges with three equivalent Se(1)Na5Ge octahedra, and edges with three equivalent Se(3)Na5Ge octahedra. The corner-sharing octahedral tilt angles range from 0-88°.