Eu2Ir2O7 crystallizes in the trigonal R-3m space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded to two equivalent O(1) and six equivalent O(3) atoms to form distorted EuO8 hexagonal bipyramids that share edges with six equivalent Eu(2)O8 hexagonal bipyramids and edges with six equivalent Ir(1)O6 octahedra. In the second Eu site, Eu(2) is bonded to two equivalent O(1), two equivalent O(3), and four equivalent O(2) atoms to form distorted EuO8 hexagonal bipyramids that share edges with two equivalent Eu(1)O8 hexagonal bipyramids, edges with four equivalent Eu(2)O8 hexagonal bipyramids, edges with two equivalent Ir(2)O6 octahedra, and edges with four equivalent Ir(1)O6 octahedra. There are two inequivalent Ir sites. In the first Ir site, Ir(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form IrO6 octahedra that share corners with two equivalent Ir(2)O6 octahedra, corners with four equivalent Ir(1)O6 octahedra, edges with two equivalent Eu(1)O8 hexagonal bipyramids, and edges with four equivalent Eu(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 48°. In the second Ir site, Ir(2) is bonded to six equivalent O(2) atoms to form IrO6 octahedra that share corners with six equivalent Ir(1)O6 octahedra and edges with six equivalent Eu(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 48°. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Eu(1) and three equivalent Eu(2) atoms to form OEu4 tetrahedra that share corners with four equivalent O(1)Eu4 tetrahedra, corners with six equivalent O(2)Eu2Ir2 tetrahedra, corners with six equivalent O(3)Eu2Ir2 tetrahedra, edges with three equivalent O(2)Eu2Ir2 tetrahedra, and edges with three equivalent O(3)Eu2Ir2 tetrahedra. In the second O site, O(2) is bonded to two equivalent Eu(2), one Ir(1), and one Ir(2) atom to form distorted OEu2Ir2 tetrahedra that share corners with two equivalent O(1)Eu4 tetrahedra, corners with four equivalent O(3)Eu2Ir2 tetrahedra, corners with eight equivalent O(2)Eu2Ir2 tetrahedra,  an edgeedge with one O(1)Eu4 tetrahedra, edges with two equivalent O(2)Eu2Ir2 tetrahedra, and edges with two equivalent O(3)Eu2Ir2 tetrahedra. In the third O site, O(3) is bonded to one Eu(1), one Eu(2), and two equivalent Ir(1) atoms to form distorted OEu2Ir2 tetrahedra that share corners with two equivalent O(1)Eu4 tetrahedra, corners with four equivalent O(2)Eu2Ir2 tetrahedra, corners with eight equivalent O(3)Eu2Ir2 tetrahedra,  an edgeedge with one O(1)Eu4 tetrahedra, edges with two equivalent O(2)Eu2Ir2 tetrahedra, and edges with two equivalent O(3)Eu2Ir2 tetrahedra.
Eu2Ir2O7 crystallizes in the trigonal R-3m space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded to two equivalent O(1) and six equivalent O(3) atoms to form distorted EuO8 hexagonal bipyramids that share edges with six equivalent Eu(2)O8 hexagonal bipyramids and edges with six equivalent Ir(1)O6 octahedra. Both Eu(1)-O(1) bond lengths are 2.25 Å. All Eu(1)-O(3) bond lengths are 2.54 Å. In the second Eu site, Eu(2) is bonded to two equivalent O(1), two equivalent O(3), and four equivalent O(2) atoms to form distorted EuO8 hexagonal bipyramids that share edges with two equivalent Eu(1)O8 hexagonal bipyramids, edges with four equivalent Eu(2)O8 hexagonal bipyramids, edges with two equivalent Ir(2)O6 octahedra, and edges with four equivalent Ir(1)O6 octahedra. Both Eu(2)-O(1) bond lengths are 2.24 Å. Both Eu(2)-O(3) bond lengths are 2.54 Å. All Eu(2)-O(2) bond lengths are 2.54 Å. There are two inequivalent Ir sites. In the first Ir site, Ir(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form IrO6 octahedra that share corners with two equivalent Ir(2)O6 octahedra, corners with four equivalent Ir(1)O6 octahedra, edges with two equivalent Eu(1)O8 hexagonal bipyramids, and edges with four equivalent Eu(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 48°. Both Ir(1)-O(2) bond lengths are 2.00 Å. All Ir(1)-O(3) bond lengths are 2.00 Å. In the second Ir site, Ir(2) is bonded to six equivalent O(2) atoms to form IrO6 octahedra that share corners with six equivalent Ir(1)O6 octahedra and edges with six equivalent Eu(2)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 48°. All Ir(2)-O(2) bond lengths are 2.00 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Eu(1) and three equivalent Eu(2) atoms to form OEu4 tetrahedra that share corners with four equivalent O(1)Eu4 tetrahedra, corners with six equivalent O(2)Eu2Ir2 tetrahedra, corners with six equivalent O(3)Eu2Ir2 tetrahedra, edges with three equivalent O(2)Eu2Ir2 tetrahedra, and edges with three equivalent O(3)Eu2Ir2 tetrahedra. In the second O site, O(2) is bonded to two equivalent Eu(2), one Ir(1), and one Ir(2) atom to form distorted OEu2Ir2 tetrahedra that share corners with two equivalent O(1)Eu4 tetrahedra, corners with four equivalent O(3)Eu2Ir2 tetrahedra, corners with eight equivalent O(2)Eu2Ir2 tetrahedra,  an edgeedge with one O(1)Eu4 tetrahedra, edges with two equivalent O(2)Eu2Ir2 tetrahedra, and edges with two equivalent O(3)Eu2Ir2 tetrahedra. In the third O site, O(3) is bonded to one Eu(1), one Eu(2), and two equivalent Ir(1) atoms to form distorted OEu2Ir2 tetrahedra that share corners with two equivalent O(1)Eu4 tetrahedra, corners with four equivalent O(2)Eu2Ir2 tetrahedra, corners with eight equivalent O(3)Eu2Ir2 tetrahedra,  an edgeedge with one O(1)Eu4 tetrahedra, edges with two equivalent O(2)Eu2Ir2 tetrahedra, and edges with two equivalent O(3)Eu2Ir2 tetrahedra.