La2Nb2N2O5 crystallizes in the monoclinic C2 space group. There are two inequivalent La sites. In the first La site, La(1) is bonded to one N(1), one N(3), one O(1), one O(2), one O(4), one O(5), one O(6), and one O(7) atom to form distorted LaN2O6 hexagonal bipyramids that share edges with two equivalent La(1)N2O6 hexagonal bipyramids, edges with four equivalent La(2)N3O5 hexagonal bipyramids, edges with two equivalent Nb(2)N2O4 octahedra, and edges with four equivalent Nb(1)NO5 octahedra. In the second La site, La(2) is bonded to one N(1), one N(2), one N(3), one O(1), one O(3), one O(4), one O(5), and one O(6) atom to form distorted LaN3O5 hexagonal bipyramids that share edges with two equivalent La(2)N3O5 hexagonal bipyramids, edges with four equivalent La(1)N2O6 hexagonal bipyramids, edges with two equivalent Nb(1)NO5 octahedra, and edges with four equivalent Nb(2)N2O4 octahedra. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one N(1), one O(1), one O(2), one O(5), one O(6), and one O(7) atom to form NbNO5 octahedra that share corners with two equivalent Nb(1)NO5 octahedra, corners with four equivalent Nb(2)N2O4 octahedra, edges with two equivalent La(2)N3O5 hexagonal bipyramids, and edges with four equivalent La(1)N2O6 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 39-48°. In the second Nb site, Nb(2) is bonded to one N(1), one N(2), one O(1), one O(3), one O(5), and one O(6) atom to form NbN2O4 octahedra that share corners with two equivalent Nb(2)N2O4 octahedra, corners with four equivalent Nb(1)NO5 octahedra, edges with two equivalent La(1)N2O6 hexagonal bipyramids, and edges with four equivalent La(2)N3O5 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 40-49°. There are three inequivalent N sites. In the first N site, N(1) is bonded in a 4-coordinate geometry to one La(1), one La(2), one Nb(1), and one Nb(2) atom. In the second N site, N(2) is bonded in a 4-coordinate geometry to two equivalent La(2) and two equivalent Nb(2) atoms. In the third N site, N(3) is bonded to two equivalent La(1) and two equivalent La(2) atoms to form NLa4 tetrahedra that share corners with two equivalent O(2)La2Nb2 tetrahedra, corners with two equivalent O(3)La2Nb2 tetrahedra, corners with four equivalent O(4)La4 tetrahedra, and edges with two equivalent O(5)La2Nb2 tetrahedra. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one La(1), one La(2), one Nb(1), and one Nb(2) atom. In the second O site, O(2) is bonded to two equivalent La(1) and two equivalent Nb(1) atoms to form distorted OLa2Nb2 tetrahedra that share corners with two equivalent N(3)La4 tetrahedra,  an edgeedge with one O(4)La4 tetrahedra, and edges with two equivalent O(5)La2Nb2 tetrahedra. In the third O site, O(3) is bonded to two equivalent La(2) and two equivalent Nb(2) atoms to form distorted OLa2Nb2 tetrahedra that share corners with two equivalent N(3)La4 tetrahedra,  an edgeedge with one O(4)La4 tetrahedra, and edges with two equivalent O(5)La2Nb2 tetrahedra. In the fourth O site, O(4) is bonded to two equivalent La(1) and two equivalent La(2) atoms to form OLa4 tetrahedra that share corners with four equivalent N(3)La4 tetrahedra, corners with four equivalent O(5)La2Nb2 tetrahedra,  an edgeedge with one O(2)La2Nb2 tetrahedra, and  an edgeedge with one O(3)La2Nb2 tetrahedra. In the fifth O site, O(5) is bonded to one La(1), one La(2), one Nb(1), and one Nb(2) atom to form distorted OLa2Nb2 tetrahedra that share corners with two equivalent O(4)La4 tetrahedra,  an edgeedge with one N(3)La4 tetrahedra,  an edgeedge with one O(2)La2Nb2 tetrahedra, and  an edgeedge with one O(3)La2Nb2 tetrahedra. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one La(1), one La(2), one Nb(1), and one Nb(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to two equivalent La(1) and two equivalent Nb(1) atoms.
La2Nb2N2O5 crystallizes in the monoclinic C2 space group. There are two inequivalent La sites. In the first La site, La(1) is bonded to one N(1), one N(3), one O(1), one O(2), one O(4), one O(5), one O(6), and one O(7) atom to form distorted LaN2O6 hexagonal bipyramids that share edges with two equivalent La(1)N2O6 hexagonal bipyramids, edges with four equivalent La(2)N3O5 hexagonal bipyramids, edges with two equivalent Nb(2)N2O4 octahedra, and edges with four equivalent Nb(1)NO5 octahedra. The La(1)-N(1) bond length is 2.75 Å. The La(1)-N(3) bond length is 2.29 Å. The La(1)-O(1) bond length is 2.68 Å. The La(1)-O(2) bond length is 2.69 Å. The La(1)-O(4) bond length is 2.36 Å. The La(1)-O(5) bond length is 2.65 Å. The La(1)-O(6) bond length is 2.71 Å. The La(1)-O(7) bond length is 2.73 Å. In the second La site, La(2) is bonded to one N(1), one N(2), one N(3), one O(1), one O(3), one O(4), one O(5), and one O(6) atom to form distorted LaN3O5 hexagonal bipyramids that share edges with two equivalent La(2)N3O5 hexagonal bipyramids, edges with four equivalent La(1)N2O6 hexagonal bipyramids, edges with two equivalent Nb(1)NO5 octahedra, and edges with four equivalent Nb(2)N2O4 octahedra. The La(2)-N(1) bond length is 2.77 Å. The La(2)-N(2) bond length is 2.75 Å. The La(2)-N(3) bond length is 2.31 Å. The La(2)-O(1) bond length is 2.70 Å. The La(2)-O(3) bond length is 2.64 Å. The La(2)-O(4) bond length is 2.37 Å. The La(2)-O(5) bond length is 2.66 Å. The La(2)-O(6) bond length is 2.71 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one N(1), one O(1), one O(2), one O(5), one O(6), and one O(7) atom to form NbNO5 octahedra that share corners with two equivalent Nb(1)NO5 octahedra, corners with four equivalent Nb(2)N2O4 octahedra, edges with two equivalent La(2)N3O5 hexagonal bipyramids, and edges with four equivalent La(1)N2O6 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 39-48°. The Nb(1)-N(1) bond length is 1.93 Å. The Nb(1)-O(1) bond length is 2.07 Å. The Nb(1)-O(2) bond length is 2.07 Å. The Nb(1)-O(5) bond length is 2.18 Å. The Nb(1)-O(6) bond length is 2.03 Å. The Nb(1)-O(7) bond length is 2.04 Å. In the second Nb site, Nb(2) is bonded to one N(1), one N(2), one O(1), one O(3), one O(5), and one O(6) atom to form NbN2O4 octahedra that share corners with two equivalent Nb(2)N2O4 octahedra, corners with four equivalent Nb(1)NO5 octahedra, edges with two equivalent La(1)N2O6 hexagonal bipyramids, and edges with four equivalent La(2)N3O5 hexagonal bipyramids. The corner-sharing octahedral tilt angles range from 40-49°. The Nb(2)-N(1) bond length is 2.02 Å. The Nb(2)-N(2) bond length is 1.97 Å. The Nb(2)-O(1) bond length is 2.06 Å. The Nb(2)-O(3) bond length is 2.15 Å. The Nb(2)-O(5) bond length is 2.11 Å. The Nb(2)-O(6) bond length is 2.09 Å. There are three inequivalent N sites. In the first N site, N(1) is bonded in a 4-coordinate geometry to one La(1), one La(2), one Nb(1), and one Nb(2) atom. In the second N site, N(2) is bonded in a 4-coordinate geometry to two equivalent La(2) and two equivalent Nb(2) atoms. In the third N site, N(3) is bonded to two equivalent La(1) and two equivalent La(2) atoms to form NLa4 tetrahedra that share corners with two equivalent O(2)La2Nb2 tetrahedra, corners with two equivalent O(3)La2Nb2 tetrahedra, corners with four equivalent O(4)La4 tetrahedra, and edges with two equivalent O(5)La2Nb2 tetrahedra. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one La(1), one La(2), one Nb(1), and one Nb(2) atom. In the second O site, O(2) is bonded to two equivalent La(1) and two equivalent Nb(1) atoms to form distorted OLa2Nb2 tetrahedra that share corners with two equivalent N(3)La4 tetrahedra,  an edgeedge with one O(4)La4 tetrahedra, and edges with two equivalent O(5)La2Nb2 tetrahedra. In the third O site, O(3) is bonded to two equivalent La(2) and two equivalent Nb(2) atoms to form distorted OLa2Nb2 tetrahedra that share corners with two equivalent N(3)La4 tetrahedra,  an edgeedge with one O(4)La4 tetrahedra, and edges with two equivalent O(5)La2Nb2 tetrahedra. In the fourth O site, O(4) is bonded to two equivalent La(1) and two equivalent La(2) atoms to form OLa4 tetrahedra that share corners with four equivalent N(3)La4 tetrahedra, corners with four equivalent O(5)La2Nb2 tetrahedra,  an edgeedge with one O(2)La2Nb2 tetrahedra, and  an edgeedge with one O(3)La2Nb2 tetrahedra. In the fifth O site, O(5) is bonded to one La(1), one La(2), one Nb(1), and one Nb(2) atom to form distorted OLa2Nb2 tetrahedra that share corners with two equivalent O(4)La4 tetrahedra,  an edgeedge with one N(3)La4 tetrahedra,  an edgeedge with one O(2)La2Nb2 tetrahedra, and  an edgeedge with one O(3)La2Nb2 tetrahedra. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one La(1), one La(2), one Nb(1), and one Nb(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to two equivalent La(1) and two equivalent Nb(1) atoms.