K7Ta(SO4)6 crystallizes in the trigonal R-3 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to six equivalent O(4) atoms to form distorted KO6 octahedra that share corners with six equivalent S(1)O4 tetrahedra and edges with six equivalent K(2)O6 octahedra. In the second K site, K(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form KO6 octahedra that share corners with two equivalent K(2)O6 octahedra, corners with six equivalent S(1)O4 tetrahedra,  an edgeedge with one K(1)O6 octahedra, and edges with two equivalent K(2)O6 octahedra. The corner-sharing octahedral tilt angles are 75°. Ta(1) is bonded to six equivalent O(3) atoms to form TaO6 octahedra that share corners with six equivalent S(1)O4 tetrahedra. S(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SO4 tetrahedra that share  a cornercorner with one K(1)O6 octahedra,  a cornercorner with one Ta(1)O6 octahedra, and corners with six equivalent K(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 31-66°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to two equivalent K(2) and one S(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent K(2) and one S(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Ta(1) and one S(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one K(1), two equivalent K(2), and one S(1) atom.
K7Ta(SO4)6 crystallizes in the trigonal R-3 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to six equivalent O(4) atoms to form distorted KO6 octahedra that share corners with six equivalent S(1)O4 tetrahedra and edges with six equivalent K(2)O6 octahedra. All K(1)-O(4) bond lengths are 2.69 Å. In the second K site, K(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form KO6 octahedra that share corners with two equivalent K(2)O6 octahedra, corners with six equivalent S(1)O4 tetrahedra,  an edgeedge with one K(1)O6 octahedra, and edges with two equivalent K(2)O6 octahedra. The corner-sharing octahedral tilt angles are 75°. There is one shorter (2.71 Å) and one longer (2.76 Å) K(2)-O(1) bond length. There is one shorter (2.67 Å) and one longer (2.71 Å) K(2)-O(2) bond length. There is one shorter (2.76 Å) and one longer (2.86 Å) K(2)-O(4) bond length. Ta(1) is bonded to six equivalent O(3) atoms to form TaO6 octahedra that share corners with six equivalent S(1)O4 tetrahedra. All Ta(1)-O(3) bond lengths are 1.97 Å. S(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SO4 tetrahedra that share  a cornercorner with one K(1)O6 octahedra,  a cornercorner with one Ta(1)O6 octahedra, and corners with six equivalent K(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 31-66°. The S(1)-O(1) bond length is 1.45 Å. The S(1)-O(2) bond length is 1.45 Å. The S(1)-O(3) bond length is 1.56 Å. The S(1)-O(4) bond length is 1.46 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to two equivalent K(2) and one S(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent K(2) and one S(1) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Ta(1) and one S(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one K(1), two equivalent K(2), and one S(1) atom.