LiY2(FeO2)4 crystallizes in the monoclinic C2/m space group. Li(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form distorted LiO6 octahedra that share corners with six equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with four equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-7°. Y(1) is bonded in a rectangular see-saw-like geometry to one O(2), one O(3), and two equivalent O(1) atoms. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form FeO6 octahedra that share edges with two equivalent Li(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with four equivalent Fe(3)O6 octahedra. In the second Fe site, Fe(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form FeO6 octahedra that share corners with six equivalent Li(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with four equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-7°. In the third Fe site, Fe(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share edges with two equivalent Li(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Li(1), one Y(1), one Fe(1), one Fe(2), and one Fe(3) atom to form OLiYFe3 square pyramids that share corners with five equivalent O(1)LiYFe3 square pyramids, corners with three equivalent O(3)YFe3 tetrahedra, edges with three equivalent O(1)LiYFe3 square pyramids, and  an edgeedge with one O(3)YFe3 tetrahedra. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Li(1), one Y(1), one Fe(2), and two equivalent Fe(3) atoms. In the third O site, O(3) is bonded to one Y(1), one Fe(1), and two equivalent Fe(3) atoms to form OYFe3 tetrahedra that share corners with six equivalent O(1)LiYFe3 square pyramids, corners with three equivalent O(3)YFe3 tetrahedra, and edges with two equivalent O(1)LiYFe3 square pyramids.
LiY2(FeO2)4 crystallizes in the monoclinic C2/m space group. Li(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form distorted LiO6 octahedra that share corners with six equivalent Fe(2)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with four equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-7°. Both Li(1)-O(2) bond lengths are 2.53 Å. All Li(1)-O(1) bond lengths are 2.17 Å. Y(1) is bonded in a rectangular see-saw-like geometry to one O(2), one O(3), and two equivalent O(1) atoms. The Y(1)-O(2) bond length is 2.13 Å. The Y(1)-O(3) bond length is 2.16 Å. Both Y(1)-O(1) bond lengths are 2.18 Å. There are three inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form FeO6 octahedra that share edges with two equivalent Li(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with four equivalent Fe(3)O6 octahedra. Both Fe(1)-O(3) bond lengths are 2.01 Å. All Fe(1)-O(1) bond lengths are 2.11 Å. In the second Fe site, Fe(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form FeO6 octahedra that share corners with six equivalent Li(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, and edges with four equivalent Fe(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 3-7°. Both Fe(2)-O(2) bond lengths are 2.09 Å. All Fe(2)-O(1) bond lengths are 2.34 Å. In the third Fe site, Fe(3) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form FeO6 octahedra that share edges with two equivalent Li(1)O6 octahedra, edges with two equivalent Fe(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and edges with two equivalent Fe(3)O6 octahedra. Both Fe(3)-O(1) bond lengths are 2.32 Å. Both Fe(3)-O(2) bond lengths are 2.32 Å. Both Fe(3)-O(3) bond lengths are 2.00 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Li(1), one Y(1), one Fe(1), one Fe(2), and one Fe(3) atom to form OLiYFe3 square pyramids that share corners with five equivalent O(1)LiYFe3 square pyramids, corners with three equivalent O(3)YFe3 tetrahedra, edges with three equivalent O(1)LiYFe3 square pyramids, and  an edgeedge with one O(3)YFe3 tetrahedra. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Li(1), one Y(1), one Fe(2), and two equivalent Fe(3) atoms. In the third O site, O(3) is bonded to one Y(1), one Fe(1), and two equivalent Fe(3) atoms to form OYFe3 tetrahedra that share corners with six equivalent O(1)LiYFe3 square pyramids, corners with three equivalent O(3)YFe3 tetrahedra, and edges with two equivalent O(1)LiYFe3 square pyramids.