CdAl4O7 crystallizes in the monoclinic C2/c space group. Cd(1) is bonded to one O(1), two equivalent O(2), and two equivalent O(3) atoms to form CdO5 trigonal bipyramids that share corners with four equivalent Al(2)O4 tetrahedra and corners with six equivalent Al(1)O4 tetrahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form AlO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra, corners with three equivalent Al(2)O4 tetrahedra, and corners with three equivalent Cd(1)O5 trigonal bipyramids. In the second Al site, Al(2) is bonded to one O(1), one O(3), and two equivalent O(4) atoms to form AlO4 tetrahedra that share corners with three equivalent Al(1)O4 tetrahedra, corners with three equivalent Al(2)O4 tetrahedra, and corners with two equivalent Cd(1)O5 trigonal bipyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Cd(1) and two equivalent Al(2) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Cd(1) and two equivalent Al(1) atoms. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Cd(1), one Al(1), and one Al(2) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Al(1) and two equivalent Al(2) atoms.
CdAl4O7 crystallizes in the monoclinic C2/c space group. Cd(1) is bonded to one O(1), two equivalent O(2), and two equivalent O(3) atoms to form CdO5 trigonal bipyramids that share corners with four equivalent Al(2)O4 tetrahedra and corners with six equivalent Al(1)O4 tetrahedra. The Cd(1)-O(1) bond length is 2.32 Å. Both Cd(1)-O(2) bond lengths are 2.26 Å. Both Cd(1)-O(3) bond lengths are 2.29 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form AlO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra, corners with three equivalent Al(2)O4 tetrahedra, and corners with three equivalent Cd(1)O5 trigonal bipyramids. The Al(1)-O(3) bond length is 1.74 Å. The Al(1)-O(4) bond length is 1.80 Å. There is one shorter (1.75 Å) and one longer (1.76 Å) Al(1)-O(2) bond length. In the second Al site, Al(2) is bonded to one O(1), one O(3), and two equivalent O(4) atoms to form AlO4 tetrahedra that share corners with three equivalent Al(1)O4 tetrahedra, corners with three equivalent Al(2)O4 tetrahedra, and corners with two equivalent Cd(1)O5 trigonal bipyramids. The Al(2)-O(1) bond length is 1.76 Å. The Al(2)-O(3) bond length is 1.73 Å. There is one shorter (1.78 Å) and one longer (1.80 Å) Al(2)-O(4) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Cd(1) and two equivalent Al(2) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Cd(1) and two equivalent Al(1) atoms. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Cd(1), one Al(1), and one Al(2) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Al(1) and two equivalent Al(2) atoms.