K2Ni(PO3)4 crystallizes in the monoclinic Cc space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(11), one O(2), one O(3), one O(4), one O(7), and one O(9) atom. In the second K site, K(2) is bonded in a 5-coordinate geometry to one O(1), one O(10), one O(2), one O(3), and one O(6) atom. Ni(1) is bonded to one O(10), one O(3), one O(4), one O(5), one O(7), and one O(9) atom to form NiO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and corners with two equivalent P(4)O4 tetrahedra. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(11), one O(4), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and  a cornercorner with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. In the second P site, P(2) is bonded to one O(11), one O(12), one O(3), and one O(9) atom to form PO4 tetrahedra that share corners with two equivalent Ni(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and  a cornercorner with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-50°. In the third P site, P(3) is bonded to one O(2), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and  a cornercorner with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 37°. In the fourth P site, P(4) is bonded to one O(10), one O(12), one O(5), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Ni(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and  a cornercorner with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-54°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one K(1), one K(2), and one P(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one K(1), one K(2), and one P(3) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one K(1), one K(2), one Ni(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one K(1), one Ni(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(4) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one K(2), one P(1), and one P(3) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one K(1), one Ni(1), and one P(3) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one P(3) and one P(4) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to one K(1), one Ni(1), and one P(2) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Ni(1), and one P(4) atom. In the eleventh O site, O(11) is bonded in a 2-coordinate geometry to one K(1), one P(1), and one P(2) atom. In the twelfth O site, O(12) is bonded in a distorted bent 120 degrees geometry to one P(2) and one P(4) atom.
K2Ni(PO3)4 crystallizes in the monoclinic Cc space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(11), one O(2), one O(3), one O(4), one O(7), and one O(9) atom. The K(1)-O(1) bond length is 2.65 Å. The K(1)-O(10) bond length is 2.94 Å. The K(1)-O(11) bond length is 3.03 Å. The K(1)-O(2) bond length is 2.68 Å. The K(1)-O(3) bond length is 2.75 Å. The K(1)-O(4) bond length is 3.04 Å. The K(1)-O(7) bond length is 2.94 Å. The K(1)-O(9) bond length is 3.13 Å. In the second K site, K(2) is bonded in a 5-coordinate geometry to one O(1), one O(10), one O(2), one O(3), and one O(6) atom. The K(2)-O(1) bond length is 2.77 Å. The K(2)-O(10) bond length is 2.94 Å. The K(2)-O(2) bond length is 2.84 Å. The K(2)-O(3) bond length is 2.93 Å. The K(2)-O(6) bond length is 2.84 Å. Ni(1) is bonded to one O(10), one O(3), one O(4), one O(5), one O(7), and one O(9) atom to form NiO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra,  a cornercorner with one P(3)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and corners with two equivalent P(4)O4 tetrahedra. The Ni(1)-O(10) bond length is 2.17 Å. The Ni(1)-O(3) bond length is 2.34 Å. The Ni(1)-O(4) bond length is 2.05 Å. The Ni(1)-O(5) bond length is 2.06 Å. The Ni(1)-O(7) bond length is 2.10 Å. The Ni(1)-O(9) bond length is 2.04 Å. There are four inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(11), one O(4), and one O(6) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and  a cornercorner with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles are 43°. The P(1)-O(1) bond length is 1.49 Å. The P(1)-O(11) bond length is 1.62 Å. The P(1)-O(4) bond length is 1.51 Å. The P(1)-O(6) bond length is 1.63 Å. In the second P site, P(2) is bonded to one O(11), one O(12), one O(3), and one O(9) atom to form PO4 tetrahedra that share corners with two equivalent Ni(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and  a cornercorner with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-50°. The P(2)-O(11) bond length is 1.62 Å. The P(2)-O(12) bond length is 1.62 Å. The P(2)-O(3) bond length is 1.50 Å. The P(2)-O(9) bond length is 1.50 Å. In the third P site, P(3) is bonded to one O(2), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Ni(1)O6 octahedra,  a cornercorner with one P(1)O4 tetrahedra, and  a cornercorner with one P(4)O4 tetrahedra. The corner-sharing octahedral tilt angles are 37°. The P(3)-O(2) bond length is 1.49 Å. The P(3)-O(6) bond length is 1.63 Å. The P(3)-O(7) bond length is 1.51 Å. The P(3)-O(8) bond length is 1.61 Å. In the fourth P site, P(4) is bonded to one O(10), one O(12), one O(5), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Ni(1)O6 octahedra,  a cornercorner with one P(2)O4 tetrahedra, and  a cornercorner with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-54°. The P(4)-O(10) bond length is 1.51 Å. The P(4)-O(12) bond length is 1.62 Å. The P(4)-O(5) bond length is 1.50 Å. The P(4)-O(8) bond length is 1.60 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one K(1), one K(2), and one P(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one K(1), one K(2), and one P(3) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one K(1), one K(2), one Ni(1), and one P(2) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one K(1), one Ni(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one P(4) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one K(2), one P(1), and one P(3) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one K(1), one Ni(1), and one P(3) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one P(3) and one P(4) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to one K(1), one Ni(1), and one P(2) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Ni(1), and one P(4) atom. In the eleventh O site, O(11) is bonded in a 2-coordinate geometry to one K(1), one P(1), and one P(2) atom. In the twelfth O site, O(12) is bonded in a distorted bent 120 degrees geometry to one P(2) and one P(4) atom.