Ca2Ru2O7 crystallizes in the cubic Fd-3m space group. Ca(1) is bonded to two equivalent O(2) and six equivalent O(1) atoms to form distorted CaO8 hexagonal bipyramids that share edges with six equivalent Ca(1)O8 hexagonal bipyramids and edges with six equivalent Ru(1)O6 octahedra. Ru(1) is bonded to six equivalent O(1) atoms to form RuO6 octahedra that share corners with six equivalent Ru(1)O6 octahedra and edges with six equivalent Ca(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 43°. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1) and two equivalent Ru(1) atoms to form distorted OCa2Ru2 trigonal pyramids that share corners with two equivalent O(2)Ca4 tetrahedra, corners with twelve equivalent O(1)Ca2Ru2 trigonal pyramids,  an edgeedge with one O(2)Ca4 tetrahedra, and edges with four equivalent O(1)Ca2Ru2 trigonal pyramids. In the second O site, O(2) is bonded to four equivalent Ca(1) atoms to form OCa4 tetrahedra that share corners with four equivalent O(2)Ca4 tetrahedra, corners with twelve equivalent O(1)Ca2Ru2 trigonal pyramids, and edges with six equivalent O(1)Ca2Ru2 trigonal pyramids.
Ca2Ru2O7 crystallizes in the cubic Fd-3m space group. Ca(1) is bonded to two equivalent O(2) and six equivalent O(1) atoms to form distorted CaO8 hexagonal bipyramids that share edges with six equivalent Ca(1)O8 hexagonal bipyramids and edges with six equivalent Ru(1)O6 octahedra. Both Ca(1)-O(2) bond lengths are 2.22 Å. All Ca(1)-O(1) bond lengths are 2.58 Å. Ru(1) is bonded to six equivalent O(1) atoms to form RuO6 octahedra that share corners with six equivalent Ru(1)O6 octahedra and edges with six equivalent Ca(1)O8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 43°. All Ru(1)-O(1) bond lengths are 1.95 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1) and two equivalent Ru(1) atoms to form distorted OCa2Ru2 trigonal pyramids that share corners with two equivalent O(2)Ca4 tetrahedra, corners with twelve equivalent O(1)Ca2Ru2 trigonal pyramids,  an edgeedge with one O(2)Ca4 tetrahedra, and edges with four equivalent O(1)Ca2Ru2 trigonal pyramids. In the second O site, O(2) is bonded to four equivalent Ca(1) atoms to form OCa4 tetrahedra that share corners with four equivalent O(2)Ca4 tetrahedra, corners with twelve equivalent O(1)Ca2Ru2 trigonal pyramids, and edges with six equivalent O(1)Ca2Ru2 trigonal pyramids.