Ta3Si6N11 crystallizes in the tetragonal P4bm space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 6-coordinate geometry to one N(3), one N(4), two equivalent N(1), and two equivalent N(2) atoms. In the second Ta site, Ta(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 in a rectangular see-saw-like geometry to one N(3), one N(4), and two equivalent N(2) atoms. There are four inequivalent N sites. In the first N site, N(3) is bonded to one Ta(1), one Si(2), and two equivalent Si(1) atoms to form a mixture of distorted corner and edge-sharing NTaSi3 trigonal pyramids. In the second N site, N(4) is bonded in a rectangular see-saw-like geometry to two equivalent Ta(1) and two equivalent Si(2) atoms. In the third N site, N(1) is bonded to one Ta(1), one Ta(2), and two equivalent Si(1) atoms to form distorted NTa2Si2 trigonal pyramids that share  a cornercorner with one N(3)TaSi3 trigonal pyramid, corners with two equivalent N(1)Ta2Si2 trigonal pyramids,  an edgeedge with one N(3)TaSi3 trigonal pyramid, and edges with two equivalent N(1)Ta2Si2 trigonal pyramids. In the fourth N site, N(2) is bonded in a 4-coordinate geometry to one Ta(1), one Ta(2), one Si(1), and one Si(2) atom.
Ta3Si6N11 crystallizes in the tetragonal P4bm space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 6-coordinate geometry to one N(3), one N(4), two equivalent N(1), and two equivalent N(2) atoms. The Ta(1)-N(3) bond length is 2.38 Å. The Ta(1)-N(4) bond length is 2.41 Å. Both Ta(1)-N(1) bond lengths are 2.11 Å. Both Ta(1)-N(2) bond lengths are 2.40 Å. In the second Ta site, Ta(2) is bonded in a 8-coordinate geometry to four equivalent N(1) and four equivalent N(2) atoms. All Ta(2)-N(1) bond lengths are 2.40 Å. All Ta(2)-N(2) bond lengths are 2.35 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 1.74 Å. There is one shorter (1.71 Å) and one longer (1.73 Å) Si(1)-N(1) bond length. In the second Si site, Si(2) is bonded in a rectangular see-saw-like geometry to one N(3), one N(4), and two equivalent N(2) atoms. The Si(2)-N(3) bond length is 1.74 Å. The Si(2)-N(4) bond length is 1.75 Å. Both Si(2)-N(2) bond lengths are 1.82 Å. There are four inequivalent N sites. In the first N site, N(3) is bonded to one Ta(1), one Si(2), and two equivalent Si(1) atoms to form a mixture of distorted corner and edge-sharing NTaSi3 trigonal pyramids. In the second N site, N(4) is bonded in a rectangular see-saw-like geometry to two equivalent Ta(1) and two equivalent Si(2) atoms. In the third N site, N(1) is bonded to one Ta(1), one Ta(2), and two equivalent Si(1) atoms to form distorted NTa2Si2 trigonal pyramids that share  a cornercorner with one N(3)TaSi3 trigonal pyramid, corners with two equivalent N(1)Ta2Si2 trigonal pyramids,  an edgeedge with one N(3)TaSi3 trigonal pyramid, and edges with two equivalent N(1)Ta2Si2 trigonal pyramids. In the fourth N site, N(2) is bonded in a 4-coordinate geometry to one Ta(1), one Ta(2), one Si(1), and one Si(2) atom.