Cd3(AsO4)2 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Cd sites. In the first Cd site, Cd(1) is bonded to one O(1), two equivalent O(4), and two equivalent O(8) atoms to form distorted CdO5 trigonal bipyramids that share corners with two equivalent As(2)O4 tetrahedra, corners with three equivalent As(1)O4 tetrahedra,  a cornercorner with one Cd(2)O5 trigonal bipyramid, and edges with two equivalent Cd(1)O5 trigonal bipyramids. In the second Cd site, Cd(2) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(7) atom to form CdO5 trigonal bipyramids that share corners with two equivalent As(2)O4 tetrahedra, corners with three equivalent As(1)O4 tetrahedra, and  a cornercorner with one Cd(1)O5 trigonal bipyramid. In the third Cd site, Cd(3) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(5), one O(7), and two equivalent O(6) atoms. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AsO4 tetrahedra that share corners with three equivalent Cd(1)O5 trigonal bipyramids and corners with three equivalent Cd(2)O5 trigonal bipyramids. In the second As site, As(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form AsO4 tetrahedra that share corners with two equivalent Cd(1)O5 trigonal bipyramids and corners with two equivalent Cd(2)O5 trigonal bipyramids. There are eight inequivalent O sites. In the first O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Cd(1) and one As(1) atom. In the second O site, O(5) is bonded in a distorted trigonal planar geometry to one Cd(2), one Cd(3), and one As(2) atom. In the third O site, O(6) is bonded in a distorted trigonal planar geometry to two equivalent Cd(3) and one As(2) atom. In the fourth O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Cd(2), one Cd(3), and one As(2) atom. In the fifth O site, O(8) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Cd(1) and one As(2) atom. In the sixth O site, O(1) is bonded in a distorted trigonal planar geometry to one Cd(1), one Cd(2), and one As(1) atom. In the seventh O site, O(2) is bonded in a 3-coordinate geometry to one Cd(2), one Cd(3), and one As(1) atom. In the eighth O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Cd(2), one Cd(3), and one As(1) atom.
Cd3(AsO4)2 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Cd sites. In the first Cd site, Cd(1) is bonded to one O(1), two equivalent O(4), and two equivalent O(8) atoms to form distorted CdO5 trigonal bipyramids that share corners with two equivalent As(2)O4 tetrahedra, corners with three equivalent As(1)O4 tetrahedra,  a cornercorner with one Cd(2)O5 trigonal bipyramid, and edges with two equivalent Cd(1)O5 trigonal bipyramids. The Cd(1)-O(1) bond length is 2.23 Å. There is one shorter (2.28 Å) and one longer (2.34 Å) Cd(1)-O(4) bond length. There is one shorter (2.19 Å) and one longer (2.32 Å) Cd(1)-O(8) bond length. In the second Cd site, Cd(2) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(7) atom to form CdO5 trigonal bipyramids that share corners with two equivalent As(2)O4 tetrahedra, corners with three equivalent As(1)O4 tetrahedra, and  a cornercorner with one Cd(1)O5 trigonal bipyramid. The Cd(2)-O(1) bond length is 2.34 Å. The Cd(2)-O(2) bond length is 2.13 Å. The Cd(2)-O(3) bond length is 2.14 Å. The Cd(2)-O(5) bond length is 2.29 Å. The Cd(2)-O(7) bond length is 2.40 Å. In the third Cd site, Cd(3) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(5), one O(7), and two equivalent O(6) atoms. The Cd(3)-O(2) bond length is 2.49 Å. The Cd(3)-O(3) bond length is 2.46 Å. The Cd(3)-O(5) bond length is 2.47 Å. The Cd(3)-O(7) bond length is 2.22 Å. There is one shorter (2.24 Å) and one longer (2.40 Å) Cd(3)-O(6) bond length. There are two inequivalent As sites. In the first As site, As(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AsO4 tetrahedra that share corners with three equivalent Cd(1)O5 trigonal bipyramids and corners with three equivalent Cd(2)O5 trigonal bipyramids. The As(1)-O(1) bond length is 1.71 Å. The As(1)-O(2) bond length is 1.69 Å. The As(1)-O(3) bond length is 1.70 Å. The As(1)-O(4) bond length is 1.70 Å. In the second As site, As(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form AsO4 tetrahedra that share corners with two equivalent Cd(1)O5 trigonal bipyramids and corners with two equivalent Cd(2)O5 trigonal bipyramids. The As(2)-O(5) bond length is 1.70 Å. The As(2)-O(6) bond length is 1.70 Å. The As(2)-O(7) bond length is 1.70 Å. The As(2)-O(8) bond length is 1.71 Å. There are eight inequivalent O sites. In the first O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Cd(1) and one As(1) atom. In the second O site, O(5) is bonded in a distorted trigonal planar geometry to one Cd(2), one Cd(3), and one As(2) atom. In the third O site, O(6) is bonded in a distorted trigonal planar geometry to two equivalent Cd(3) and one As(2) atom. In the fourth O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Cd(2), one Cd(3), and one As(2) atom. In the fifth O site, O(8) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Cd(1) and one As(2) atom. In the sixth O site, O(1) is bonded in a distorted trigonal planar geometry to one Cd(1), one Cd(2), and one As(1) atom. In the seventh O site, O(2) is bonded in a 3-coordinate geometry to one Cd(2), one Cd(3), and one As(1) atom. In the eighth O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Cd(2), one Cd(3), and one As(1) atom.