La2NiO4 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 8-coordinate geometry to one O(1), one O(4), three equivalent O(2), and three equivalent O(3) atoms. In the second La site, La(2) is bonded in a 9-coordinate geometry to one O(2), two equivalent O(3), two equivalent O(4), and four equivalent O(1) atoms. Ni(1) is bonded to one O(1), one O(2), one O(3), and two equivalent O(4) atoms to form corner-sharing NiO5 square pyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one La(1), four equivalent La(2), and one Ni(1) atom. In the second O site, O(2) is bonded to one La(2), three equivalent La(1), and one Ni(1) atom to form OLa4Ni trigonal bipyramids that share  a cornercorner with one O(4)La3Ni2 square pyramid, corners with six equivalent O(2)La4Ni trigonal bipyramids, and edges with three equivalent O(4)La3Ni2 square pyramids. In the third O site, O(3) is bonded in a 3-coordinate geometry to two equivalent La(2), three equivalent La(1), and one Ni(1) atom. In the fourth O site, O(4) is bonded to one La(1), two equivalent La(2), and two equivalent Ni(1) atoms to form distorted OLa3Ni2 square pyramids that share corners with four equivalent O(4)La3Ni2 square pyramids,  a cornercorner with one O(2)La4Ni trigonal bipyramid, and edges with three equivalent O(2)La4Ni trigonal bipyramids.
La2NiO4 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 8-coordinate geometry to one O(1), one O(4), three equivalent O(2), and three equivalent O(3) atoms. The La(1)-O(1) bond length is 2.35 Å. The La(1)-O(4) bond length is 2.69 Å. There are two shorter (2.32 Å) and one longer (2.58 Å) La(1)-O(2) bond length. There is one shorter (2.75 Å) and two longer (2.93 Å) La(1)-O(3) bond lengths. In the second La site, La(2) is bonded in a 9-coordinate geometry to one O(2), two equivalent O(3), two equivalent O(4), and four equivalent O(1) atoms. The La(2)-O(2) bond length is 2.65 Å. Both La(2)-O(3) bond lengths are 2.39 Å. There is one shorter (2.38 Å) and one longer (2.67 Å) La(2)-O(4) bond length. There are two shorter (2.84 Å) and two longer (2.90 Å) La(2)-O(1) bond lengths. Ni(1) is bonded to one O(1), one O(2), one O(3), and two equivalent O(4) atoms to form corner-sharing NiO5 square pyramids. The Ni(1)-O(1) bond length is 2.20 Å. The Ni(1)-O(2) bond length is 2.17 Å. The Ni(1)-O(3) bond length is 1.94 Å. Both Ni(1)-O(4) bond lengths are 2.01 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one La(1), four equivalent La(2), and one Ni(1) atom. In the second O site, O(2) is bonded to one La(2), three equivalent La(1), and one Ni(1) atom to form OLa4Ni trigonal bipyramids that share  a cornercorner with one O(4)La3Ni2 square pyramid, corners with six equivalent O(2)La4Ni trigonal bipyramids, and edges with three equivalent O(4)La3Ni2 square pyramids. In the third O site, O(3) is bonded in a 3-coordinate geometry to two equivalent La(2), three equivalent La(1), and one Ni(1) atom. In the fourth O site, O(4) is bonded to one La(1), two equivalent La(2), and two equivalent Ni(1) atoms to form distorted OLa3Ni2 square pyramids that share corners with four equivalent O(4)La3Ni2 square pyramids,  a cornercorner with one O(2)La4Ni trigonal bipyramid, and edges with three equivalent O(2)La4Ni trigonal bipyramids.