KW2AsO9 crystallizes in the orthorhombic P2_12_12_1 space group. K(1) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(7), one O(8), one O(9), and two equivalent O(6) atoms. There are two inequivalent W sites. In the first W site, W(1) is bonded to one O(2), one O(3), one O(6), one O(7), and two equivalent O(1) atoms to form distorted WO6 octahedra that share corners with two equivalent W(1)O6 octahedra, corners with two equivalent W(2)O6 octahedra, and  a cornercorner with one As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 24-40°. In the second W site, W(2) is bonded to one O(2), one O(3), one O(4), one O(5), one O(8), and one O(9) atom to form WO6 octahedra that share corners with two equivalent W(1)O6 octahedra and corners with three equivalent As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 24-40°. As(1) is bonded to one O(4), one O(5), one O(7), and one O(8) atom to form AsO4 tetrahedra that share  a cornercorner with one W(1)O6 octahedra and corners with three equivalent W(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 28-53°. There are nine inequivalent O sites. In the first O site, O(5) is bonded in a bent 150 degrees geometry to one W(2) and one As(1) atom. In the second O site, O(6) is bonded in a 3-coordinate geometry to two equivalent K(1) and one W(1) atom. In the third O site, O(7) is bonded in a 3-coordinate geometry to one K(1), one W(1), and one As(1) atom. In the fourth O site, O(8) is bonded in a distorted trigonal planar geometry to one K(1), one W(2), and one As(1) atom. In the fifth O site, O(1) is bonded in a distorted bent 150 degrees geometry to one K(1) and two equivalent W(1) atoms. In the sixth O site, O(9) is bonded in a bent 150 degrees geometry to one K(1) and one W(2) atom. In the seventh O site, O(2) is bonded in a distorted bent 150 degrees geometry to one K(1), one W(1), and one W(2) atom. In the eighth O site, O(3) is bonded in a bent 150 degrees geometry to one W(1) and one W(2) atom. In the ninth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one W(2) and one As(1) atom.
KW2AsO9 crystallizes in the orthorhombic P2_12_12_1 space group. K(1) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(7), one O(8), one O(9), and two equivalent O(6) atoms. The K(1)-O(1) bond length is 2.87 Å. The K(1)-O(2) bond length is 3.25 Å. The K(1)-O(7) bond length is 2.82 Å. The K(1)-O(8) bond length is 2.81 Å. The K(1)-O(9) bond length is 2.67 Å. There is one shorter (2.78 Å) and one longer (3.03 Å) K(1)-O(6) bond length. There are two inequivalent W sites. In the first W site, W(1) is bonded to one O(2), one O(3), one O(6), one O(7), and two equivalent O(1) atoms to form distorted WO6 octahedra that share corners with two equivalent W(1)O6 octahedra, corners with two equivalent W(2)O6 octahedra, and  a cornercorner with one As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 24-40°. The W(1)-O(2) bond length is 1.98 Å. The W(1)-O(3) bond length is 1.95 Å. The W(1)-O(6) bond length is 1.76 Å. The W(1)-O(7) bond length is 2.20 Å. There is one shorter (1.91 Å) and one longer (1.99 Å) W(1)-O(1) bond length. In the second W site, W(2) is bonded to one O(2), one O(3), one O(4), one O(5), one O(8), and one O(9) atom to form WO6 octahedra that share corners with two equivalent W(1)O6 octahedra and corners with three equivalent As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 24-40°. The W(2)-O(2) bond length is 1.90 Å. The W(2)-O(3) bond length is 1.93 Å. The W(2)-O(4) bond length is 2.04 Å. The W(2)-O(5) bond length is 2.01 Å. The W(2)-O(8) bond length is 2.18 Å. The W(2)-O(9) bond length is 1.76 Å. As(1) is bonded to one O(4), one O(5), one O(7), and one O(8) atom to form AsO4 tetrahedra that share  a cornercorner with one W(1)O6 octahedra and corners with three equivalent W(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 28-53°. The As(1)-O(4) bond length is 1.74 Å. The As(1)-O(5) bond length is 1.73 Å. The As(1)-O(7) bond length is 1.70 Å. The As(1)-O(8) bond length is 1.71 Å. There are nine inequivalent O sites. In the first O site, O(5) is bonded in a bent 150 degrees geometry to one W(2) and one As(1) atom. In the second O site, O(6) is bonded in a 3-coordinate geometry to two equivalent K(1) and one W(1) atom. In the third O site, O(7) is bonded in a 3-coordinate geometry to one K(1), one W(1), and one As(1) atom. In the fourth O site, O(8) is bonded in a distorted trigonal planar geometry to one K(1), one W(2), and one As(1) atom. In the fifth O site, O(1) is bonded in a distorted bent 150 degrees geometry to one K(1) and two equivalent W(1) atoms. In the sixth O site, O(9) is bonded in a bent 150 degrees geometry to one K(1) and one W(2) atom. In the seventh O site, O(2) is bonded in a distorted bent 150 degrees geometry to one K(1), one W(1), and one W(2) atom. In the eighth O site, O(3) is bonded in a bent 150 degrees geometry to one W(1) and one W(2) atom. In the ninth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one W(2) and one As(1) atom.