Co3Si6N11 crystallizes in the tetragonal P4bm space group. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a 3-coordinate geometry to one N(4) and two equivalent N(1) atoms. In the second Co site, Co(2) is bonded in a 8-coordinate geometry to four equivalent N(1) and four equivalent N(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one N(2), one N(3), and two equivalent N(1) atoms to form corner-sharing SiN4 tetrahedra. In the second Si site, Si(2) is bonded to one N(3), one N(4), and two equivalent N(2) atoms to form corner-sharing SiN4 tetrahedra. There are four inequivalent N sites. In the first N site, N(3) is bonded in a trigonal non-coplanar geometry to one Si(2) and two equivalent Si(1) atoms. In the second N site, N(4) is bonded in a distorted see-saw-like geometry to two equivalent Co(1) and two equivalent Si(2) atoms. In the third N site, N(1) is bonded to one Co(1), one Co(2), and two equivalent Si(1) atoms to form a mixture of distorted edge and corner-sharing NCo2Si2 tetrahedra. In the fourth N site, N(2) is bonded in a 2-coordinate geometry to one Co(2), one Si(1), and one Si(2) atom.
Co3Si6N11 crystallizes in the tetragonal P4bm space group. There are two inequivalent Co sites. In the first Co site, Co(1) is bonded in a 3-coordinate geometry to one N(4) and two equivalent N(1) atoms. The Co(1)-N(4) bond length is 2.31 Å. Both Co(1)-N(1) bond lengths are 2.01 Å. In the second Co site, Co(2) is bonded in a 8-coordinate geometry to four equivalent N(1) and four equivalent N(2) atoms. All Co(2)-N(1) bond lengths are 2.36 Å. All Co(2)-N(2) bond lengths are 2.44 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one N(2), one N(3), and two equivalent N(1) atoms to form corner-sharing SiN4 tetrahedra. The Si(1)-N(2) bond length is 1.72 Å. The Si(1)-N(3) bond length is 1.72 Å. There is one shorter (1.72 Å) and one longer (1.75 Å) Si(1)-N(1) bond length. In the second Si site, Si(2) is bonded to one N(3), one N(4), and two equivalent N(2) atoms to form corner-sharing SiN4 tetrahedra. The Si(2)-N(3) bond length is 1.76 Å. The Si(2)-N(4) bond length is 1.70 Å. Both Si(2)-N(2) bond lengths are 1.73 Å. There are four inequivalent N sites. In the first N site, N(3) is bonded in a trigonal non-coplanar geometry to one Si(2) and two equivalent Si(1) atoms. In the second N site, N(4) is bonded in a distorted see-saw-like geometry to two equivalent Co(1) and two equivalent Si(2) atoms. In the third N site, N(1) is bonded to one Co(1), one Co(2), and two equivalent Si(1) atoms to form a mixture of distorted edge and corner-sharing NCo2Si2 tetrahedra. In the fourth N site, N(2) is bonded in a 2-coordinate geometry to one Co(2), one Si(1), and one Si(2) atom.