K6Mo6C5N5Se8 crystallizes in the tetragonal I4 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 1-coordinate geometry to one N(1), two equivalent Se(1), and two equivalent Se(2) atoms. In the second K site, K(2) is bonded in a 4-coordinate geometry to four equivalent N(1), two equivalent Se(1), and two equivalent Se(2) atoms. There are three inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one C(2), two equivalent Se(1), and two equivalent Se(2) atoms to form distorted MoCSe4 square pyramids that share  an edgeedge with one Mo(2)CSe4 square pyramid,  an edgeedge with one Mo(3)Se4N square pyramid, and edges with two equivalent Mo(1)CSe4 square pyramids. In the second Mo site, Mo(2) is bonded to one C(1) and four equivalent Se(2) atoms to form distorted edge-sharing MoCSe4 square pyramids. In the third Mo site, Mo(3) is bonded to one N(2) and four equivalent Se(1) atoms to form distorted edge-sharing MoSe4N square pyramids. There are two inequivalent C sites. In the first C site, C(1) is bonded in a distorted single-bond geometry to one Mo(2) and one N(2) atom. In the second C site, C(2) is bonded in a distorted single-bond geometry to one Mo(1) and one N(1) atom. There are two inequivalent N sites. In the first N site, N(1) is bonded in a distorted single-bond geometry to one K(1), two equivalent K(2), and one C(2) atom. In the second N site, N(2) is bonded in a 1-coordinate geometry to one Mo(3) and one C(1) atom. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to one K(2), two equivalent K(1), one Mo(3), and two equivalent Mo(1) atoms. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to one K(2), two equivalent K(1), one Mo(2), and two equivalent Mo(1) atoms.
K6Mo6C5N5Se8 crystallizes in the tetragonal I4 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 1-coordinate geometry to one N(1), two equivalent Se(1), and two equivalent Se(2) atoms. The K(1)-N(1) bond length is 2.89 Å. There is one shorter (3.42 Å) and one longer (3.43 Å) K(1)-Se(1) bond length. There is one shorter (3.41 Å) and one longer (3.43 Å) K(1)-Se(2) bond length. In the second K site, K(2) is bonded in a 4-coordinate geometry to four equivalent N(1), two equivalent Se(1), and two equivalent Se(2) atoms. There are two shorter (2.97 Å) and two longer (2.98 Å) K(2)-N(1) bond lengths. Both K(2)-Se(1) bond lengths are 3.73 Å. Both K(2)-Se(2) bond lengths are 3.73 Å. There are three inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one C(2), two equivalent Se(1), and two equivalent Se(2) atoms to form distorted MoCSe4 square pyramids that share  an edgeedge with one Mo(2)CSe4 square pyramid,  an edgeedge with one Mo(3)Se4N square pyramid, and edges with two equivalent Mo(1)CSe4 square pyramids. The Mo(1)-C(2) bond length is 2.18 Å. There is one shorter (2.59 Å) and one longer (2.60 Å) Mo(1)-Se(1) bond length. There is one shorter (2.59 Å) and one longer (2.61 Å) Mo(1)-Se(2) bond length. In the second Mo site, Mo(2) is bonded to one C(1) and four equivalent Se(2) atoms to form distorted edge-sharing MoCSe4 square pyramids. The Mo(2)-C(1) bond length is 2.18 Å. All Mo(2)-Se(2) bond lengths are 2.59 Å. In the third Mo site, Mo(3) is bonded to one N(2) and four equivalent Se(1) atoms to form distorted edge-sharing MoSe4N square pyramids. The Mo(3)-N(2) bond length is 2.28 Å. All Mo(3)-Se(1) bond lengths are 2.58 Å. There are two inequivalent C sites. In the first C site, C(1) is bonded in a distorted single-bond geometry to one Mo(2) and one N(2) atom. The C(1)-N(2) bond length is 1.19 Å. In the second C site, C(2) is bonded in a distorted single-bond geometry to one Mo(1) and one N(1) atom. The C(2)-N(1) bond length is 1.19 Å. There are two inequivalent N sites. In the first N site, N(1) is bonded in a distorted single-bond geometry to one K(1), two equivalent K(2), and one C(2) atom. In the second N site, N(2) is bonded in a 1-coordinate geometry to one Mo(3) and one C(1) atom. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded in a 6-coordinate geometry to one K(2), two equivalent K(1), one Mo(3), and two equivalent Mo(1) atoms. In the second Se site, Se(2) is bonded in a 6-coordinate geometry to one K(2), two equivalent K(1), one Mo(2), and two equivalent Mo(1) atoms.