Eu2Ni2O5 crystallizes in the orthorhombic Ima2 space group. Eu(1) is bonded in a 8-coordinate geometry to one O(3), three equivalent O(2), and four equivalent O(1) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form NiO6 octahedra that share corners with four equivalent Ni(1)O6 octahedra and corners with two equivalent Ni(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 13°. In the second Ni site, Ni(2) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form NiO4 tetrahedra that share corners with two equivalent Ni(1)O6 octahedra and corners with two equivalent Ni(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 33°. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Eu(1) and two equivalent Ni(1) atoms to form distorted OEu4Ni2 octahedra that share corners with two equivalent O(1)Eu4Ni2 octahedra, corners with four equivalent O(3)Eu2Ni2 tetrahedra, edges with two equivalent O(1)Eu4Ni2 octahedra, and faces with four equivalent O(1)Eu4Ni2 octahedra. The corner-sharing octahedral tilt angles are 2°. In the second O site, O(2) is bonded in a 5-coordinate geometry to three equivalent Eu(1), one Ni(1), and one Ni(2) atom. In the third O site, O(3) is bonded to two equivalent Eu(1) and two equivalent Ni(2) atoms to form OEu2Ni2 tetrahedra that share corners with eight equivalent O(1)Eu4Ni2 octahedra and corners with two equivalent O(3)Eu2Ni2 tetrahedra. The corner-sharing octahedral tilt angles range from 24-73°.
Eu2Ni2O5 crystallizes in the orthorhombic Ima2 space group. Eu(1) is bonded in a 8-coordinate geometry to one O(3), three equivalent O(2), and four equivalent O(1) atoms. The Eu(1)-O(3) bond length is 2.33 Å. There are a spread of Eu(1)-O(2) bond distances ranging from 2.36-2.85 Å. There are two shorter (2.50 Å) and two longer (2.67 Å) Eu(1)-O(1) bond lengths. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form NiO6 octahedra that share corners with four equivalent Ni(1)O6 octahedra and corners with two equivalent Ni(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 13°. Both Ni(1)-O(2) bond lengths are 2.13 Å. There are two shorter (1.93 Å) and two longer (1.94 Å) Ni(1)-O(1) bond lengths. In the second Ni site, Ni(2) is bonded to two equivalent O(2) and two equivalent O(3) atoms to form NiO4 tetrahedra that share corners with two equivalent Ni(1)O6 octahedra and corners with two equivalent Ni(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 33°. Both Ni(2)-O(2) bond lengths are 1.95 Å. There is one shorter (2.00 Å) and one longer (2.02 Å) Ni(2)-O(3) bond length. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Eu(1) and two equivalent Ni(1) atoms to form distorted OEu4Ni2 octahedra that share corners with two equivalent O(1)Eu4Ni2 octahedra, corners with four equivalent O(3)Eu2Ni2 tetrahedra, edges with two equivalent O(1)Eu4Ni2 octahedra, and faces with four equivalent O(1)Eu4Ni2 octahedra. The corner-sharing octahedral tilt angles are 2°. In the second O site, O(2) is bonded in a 5-coordinate geometry to three equivalent Eu(1), one Ni(1), and one Ni(2) atom. In the third O site, O(3) is bonded to two equivalent Eu(1) and two equivalent Ni(2) atoms to form OEu2Ni2 tetrahedra that share corners with eight equivalent O(1)Eu4Ni2 octahedra and corners with two equivalent O(3)Eu2Ni2 tetrahedra. The corner-sharing octahedral tilt angles range from 24-73°.