KAlP4(H2O7)2 crystallizes in the triclinic P-1 space group. K(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms. Al(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form AlO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra and corners with four equivalent P(1)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with two equivalent Al(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 42-43°. In the second P site, P(2) is bonded to one O(1), one O(2), one O(4), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Al(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. There are two inequivalent H sites. In the first H site, H(1) is bonded in a distorted linear geometry to one O(1) and one O(6) atom. In the second H site, H(2) is bonded in a distorted linear geometry to one O(1) and one O(7) atom. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one P(2), one H(1), and one H(2) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one K(1), one Al(1), and one P(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one K(1), one Al(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Al(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one K(1), one P(1), and one H(1) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one K(1), one P(2), and one H(2) atom.
KAlP4(H2O7)2 crystallizes in the triclinic P-1 space group. K(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms. Both K(1)-O(2) bond lengths are 2.90 Å. Both K(1)-O(3) bond lengths are 2.74 Å. Both K(1)-O(6) bond lengths are 3.20 Å. Both K(1)-O(7) bond lengths are 2.80 Å. Al(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms to form AlO6 octahedra that share corners with two equivalent P(2)O4 tetrahedra and corners with four equivalent P(1)O4 tetrahedra. Both Al(1)-O(2) bond lengths are 1.93 Å. Both Al(1)-O(3) bond lengths are 1.91 Å. Both Al(1)-O(5) bond lengths are 1.89 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form PO4 tetrahedra that share corners with two equivalent Al(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 42-43°. The P(1)-O(3) bond length is 1.53 Å. The P(1)-O(4) bond length is 1.61 Å. The P(1)-O(5) bond length is 1.51 Å. The P(1)-O(6) bond length is 1.56 Å. In the second P site, P(2) is bonded to one O(1), one O(2), one O(4), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Al(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. The P(2)-O(1) bond length is 1.51 Å. The P(2)-O(2) bond length is 1.52 Å. The P(2)-O(4) bond length is 1.63 Å. The P(2)-O(7) bond length is 1.58 Å. There are two inequivalent H sites. In the first H site, H(1) is bonded in a distorted linear geometry to one O(1) and one O(6) atom. The H(1)-O(1) bond length is 1.59 Å. The H(1)-O(6) bond length is 1.02 Å. In the second H site, H(2) is bonded in a distorted linear geometry to one O(1) and one O(7) atom. The H(2)-O(1) bond length is 1.63 Å. The H(2)-O(7) bond length is 1.02 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one P(2), one H(1), and one H(2) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one K(1), one Al(1), and one P(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one K(1), one Al(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Al(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one K(1), one P(1), and one H(1) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one K(1), one P(2), and one H(2) atom.