Na5Co2S5 crystallizes in the tetragonal I4mm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one S(2) and four equivalent S(1) atoms. In the second Na site, Na(2) is bonded to two equivalent S(2) and four equivalent S(1) atoms to form NaS6 octahedra that share corners with two equivalent Na(2)S6 octahedra and corners with eight equivalent Co(1)S4 tetrahedra. The corner-sharing octahedra are not tilted. Co(1) is bonded to four equivalent S(1) atoms to form CoS4 tetrahedra that share corners with four equivalent Na(2)S6 octahedra and edges with two equivalent Co(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-45°. There are two inequivalent S sites. In the first S site, S(1) is bonded to one Na(2), four equivalent Na(1), and two equivalent Co(1) atoms to form distorted SNa5Co2 pentagonal bipyramids that share corners with three equivalent S(2)Na6 octahedra, corners with five equivalent S(1)Na5Co2 pentagonal bipyramids, edges with five equivalent S(1)Na5Co2 pentagonal bipyramids,  a faceface with one S(2)Na6 octahedra, and faces with two equivalent S(1)Na5Co2 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 54-84°. In the second S site, S(2) is bonded to two equivalent Na(2) and four equivalent Na(1) atoms to form distorted SNa6 octahedra that share corners with two equivalent S(2)Na6 octahedra, corners with twelve equivalent S(1)Na5Co2 pentagonal bipyramids, and faces with four equivalent S(1)Na5Co2 pentagonal bipyramids. The corner-sharing octahedra are not tilted.
Na5Co2S5 crystallizes in the tetragonal I4mm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one S(2) and four equivalent S(1) atoms. The Na(1)-S(2) bond length is 2.65 Å. There are two shorter (2.95 Å) and two longer (2.96 Å) Na(1)-S(1) bond lengths. In the second Na site, Na(2) is bonded to two equivalent S(2) and four equivalent S(1) atoms to form NaS6 octahedra that share corners with two equivalent Na(2)S6 octahedra and corners with eight equivalent Co(1)S4 tetrahedra. The corner-sharing octahedra are not tilted. There is one shorter (2.68 Å) and one longer (2.84 Å) Na(2)-S(2) bond length. All Na(2)-S(1) bond lengths are 3.01 Å. Co(1) is bonded to four equivalent S(1) atoms to form CoS4 tetrahedra that share corners with four equivalent Na(2)S6 octahedra and edges with two equivalent Co(1)S4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-45°. There are two shorter (2.18 Å) and two longer (2.19 Å) Co(1)-S(1) bond lengths. There are two inequivalent S sites. In the first S site, S(1) is bonded to one Na(2), four equivalent Na(1), and two equivalent Co(1) atoms to form distorted SNa5Co2 pentagonal bipyramids that share corners with three equivalent S(2)Na6 octahedra, corners with five equivalent S(1)Na5Co2 pentagonal bipyramids, edges with five equivalent S(1)Na5Co2 pentagonal bipyramids,  a faceface with one S(2)Na6 octahedra, and faces with two equivalent S(1)Na5Co2 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 54-84°. In the second S site, S(2) is bonded to two equivalent Na(2) and four equivalent Na(1) atoms to form distorted SNa6 octahedra that share corners with two equivalent S(2)Na6 octahedra, corners with twelve equivalent S(1)Na5Co2 pentagonal bipyramids, and faces with four equivalent S(1)Na5Co2 pentagonal bipyramids. The corner-sharing octahedra are not tilted.