Li6N4Se crystallizes in the tetragonal P4_2/nmc space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to four equivalent N(1) atoms to form distorted LiN4 tetrahedra that share corners with four equivalent Se(1)N4 tetrahedra, corners with eight equivalent Li(2)N4 tetrahedra, edges with two equivalent Li(1)N4 tetrahedra, and edges with four equivalent Li(2)N4 tetrahedra. In the second Li site, Li(2) is bonded to four equivalent N(1) atoms to form distorted LiN4 tetrahedra that share corners with two equivalent Se(1)N4 tetrahedra, corners with four equivalent Li(1)N4 tetrahedra, corners with eight equivalent Li(2)N4 tetrahedra,  an edgeedge with one Se(1)N4 tetrahedra, edges with two equivalent Li(1)N4 tetrahedra, and edges with two equivalent Li(2)N4 tetrahedra. N(1) is bonded to two equivalent Li(1), four equivalent Li(2), and one Se(1) atom to form a mixture of distorted corner and edge-sharing NLi6Se pentagonal bipyramids. Se(1) is bonded to four equivalent N(1) atoms to form SeN4 tetrahedra that share corners with eight equivalent Li(1)N4 tetrahedra, corners with eight equivalent Li(2)N4 tetrahedra, and edges with four equivalent Li(2)N4 tetrahedra.
Li6N4Se crystallizes in the tetragonal P4_2/nmc space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to four equivalent N(1) atoms to form distorted LiN4 tetrahedra that share corners with four equivalent Se(1)N4 tetrahedra, corners with eight equivalent Li(2)N4 tetrahedra, edges with two equivalent Li(1)N4 tetrahedra, and edges with four equivalent Li(2)N4 tetrahedra. There are two shorter (2.00 Å) and two longer (2.27 Å) Li(1)-N(1) bond lengths. In the second Li site, Li(2) is bonded to four equivalent N(1) atoms to form distorted LiN4 tetrahedra that share corners with two equivalent Se(1)N4 tetrahedra, corners with four equivalent Li(1)N4 tetrahedra, corners with eight equivalent Li(2)N4 tetrahedra,  an edgeedge with one Se(1)N4 tetrahedra, edges with two equivalent Li(1)N4 tetrahedra, and edges with two equivalent Li(2)N4 tetrahedra. There are two shorter (2.07 Å) and two longer (2.13 Å) Li(2)-N(1) bond lengths. N(1) is bonded to two equivalent Li(1), four equivalent Li(2), and one Se(1) atom to form a mixture of distorted corner and edge-sharing NLi6Se pentagonal bipyramids. The N(1)-Se(1) bond length is 1.80 Å. Se(1) is bonded to four equivalent N(1) atoms to form SeN4 tetrahedra that share corners with eight equivalent Li(1)N4 tetrahedra, corners with eight equivalent Li(2)N4 tetrahedra, and edges with four equivalent Li(2)N4 tetrahedra.