La3Si6N11 crystallizes in the tetragonal P4bm space group. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 8-coordinate geometry to one N(3), one N(4), two equivalent N(1), and four equivalent N(2) atoms. In the second La site, La(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 planar geometry to one La(1), one Si(2), and two equivalent Si(1) atoms. In the second N site, N(4) is bonded in a distorted rectangular see-saw-like geometry to two equivalent La(1) and two equivalent Si(2) atoms. In the third N site, N(1) is bonded to one La(1), one La(2), and two equivalent Si(1) atoms to form a mixture of distorted edge and corner-sharing NLa2Si2 trigonal pyramids. In the fourth N site, N(2) is bonded in a distorted bent 120 degrees geometry to one La(2), two equivalent La(1), one Si(1), and one Si(2) atom.
La3Si6N11 crystallizes in the tetragonal P4bm space group. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 8-coordinate geometry to one N(3), one N(4), two equivalent N(1), and four equivalent N(2) atoms. The La(1)-N(3) bond length is 2.83 Å. The La(1)-N(4) bond length is 2.62 Å. Both La(1)-N(1) bond lengths are 2.52 Å. There are two shorter (2.68 Å) and two longer (2.87 Å) La(1)-N(2) bond lengths. In the second La site, La(2) is bonded in a 8-coordinate geometry to four equivalent N(1) and four equivalent N(2) atoms. All La(2)-N(1) bond lengths are 2.64 Å. All La(2)-N(2) bond lengths are 2.64 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 1.73 Å. The Si(1)-N(3) bond length is 1.78 Å. There is one shorter (1.72 Å) and one longer (1.74 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 1.69 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 planar geometry to one La(1), one Si(2), and two equivalent Si(1) atoms. In the second N site, N(4) is bonded in a distorted rectangular see-saw-like geometry to two equivalent La(1) and two equivalent Si(2) atoms. In the third N site, N(1) is bonded to one La(1), one La(2), and two equivalent Si(1) atoms to form a mixture of distorted edge and corner-sharing NLa2Si2 trigonal pyramids. In the fourth N site, N(2) is bonded in a distorted bent 120 degrees geometry to one La(2), two equivalent La(1), one Si(1), and one Si(2) atom.