K2Al2O3F2 crystallizes in the monoclinic C2/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), and four equivalent F(1) atoms. In the second K site, K(2) is bonded in a 9-coordinate geometry to one O(2), two equivalent O(1), two equivalent O(3), and four equivalent F(1) atoms. Al(1) is bonded to one O(1), one O(2), one O(3), and one F(1) atom to form corner-sharing AlO3F tetrahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent K(1), two equivalent K(2), and two equivalent Al(1) atoms. In the second O site, O(2) is bonded in a 2-coordinate geometry to one K(2), two equivalent K(1), and two equivalent Al(1) atoms. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent K(2) and two equivalent Al(1) atoms. F(1) is bonded in a distorted single-bond geometry to two equivalent K(1), two equivalent K(2), and one Al(1) atom.
K2Al2O3F2 crystallizes in the monoclinic C2/m space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), and four equivalent F(1) atoms. Both K(1)-O(1) bond lengths are 3.08 Å. There is one shorter (2.72 Å) and one longer (3.26 Å) K(1)-O(2) bond length. There are two shorter (2.87 Å) and two longer (3.16 Å) K(1)-F(1) bond lengths. In the second K site, K(2) is bonded in a 9-coordinate geometry to one O(2), two equivalent O(1), two equivalent O(3), and four equivalent F(1) atoms. The K(2)-O(2) bond length is 3.15 Å. Both K(2)-O(1) bond lengths are 3.09 Å. Both K(2)-O(3) bond lengths are 2.79 Å. There are two shorter (2.72 Å) and two longer (3.15 Å) K(2)-F(1) bond lengths. Al(1) is bonded to one O(1), one O(2), one O(3), and one F(1) atom to form corner-sharing AlO3F tetrahedra. The Al(1)-O(1) bond length is 1.74 Å. The Al(1)-O(2) bond length is 1.75 Å. The Al(1)-O(3) bond length is 1.74 Å. The Al(1)-F(1) bond length is 1.77 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent K(1), two equivalent K(2), and two equivalent Al(1) atoms. In the second O site, O(2) is bonded in a 2-coordinate geometry to one K(2), two equivalent K(1), and two equivalent Al(1) atoms. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent K(2) and two equivalent Al(1) atoms. F(1) is bonded in a distorted single-bond geometry to two equivalent K(1), two equivalent K(2), and one Al(1) atom.