KMgPO5 crystallizes in the orthorhombic Pmn2_1 space group. K(1) is bonded in a 8-coordinate geometry to one O(1), one O(4), two equivalent O(3), and four equivalent O(2) atoms. Mg(1) is bonded to one O(1), one O(4), and four equivalent O(3) atoms to form MgO6 octahedra that share corners with four equivalent Mg(1)O6 octahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 59°. P(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form PO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and  an edgeedge with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-53°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one K(1), one Mg(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to four equivalent K(1) and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one K(1), two equivalent Mg(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted L-shaped geometry to one K(1) and one Mg(1) atom.
KMgPO5 crystallizes in the orthorhombic Pmn2_1 space group. K(1) is bonded in a 8-coordinate geometry to one O(1), one O(4), two equivalent O(3), and four equivalent O(2) atoms. The K(1)-O(1) bond length is 2.97 Å. The K(1)-O(4) bond length is 3.01 Å. Both K(1)-O(3) bond lengths are 3.23 Å. There are a spread of K(1)-O(2) bond distances ranging from 2.72-2.80 Å. Mg(1) is bonded to one O(1), one O(4), and four equivalent O(3) atoms to form MgO6 octahedra that share corners with four equivalent Mg(1)O6 octahedra, corners with three equivalent P(1)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 59°. The Mg(1)-O(1) bond length is 2.03 Å. The Mg(1)-O(4) bond length is 2.17 Å. There are two shorter (2.05 Å) and two longer (2.18 Å) Mg(1)-O(3) bond lengths. P(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form PO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and  an edgeedge with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 44-53°. The P(1)-O(1) bond length is 1.55 Å. The P(1)-O(2) bond length is 1.53 Å. Both P(1)-O(3) bond lengths are 1.57 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one K(1), one Mg(1), and one P(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to four equivalent K(1) and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one K(1), two equivalent Mg(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a distorted L-shaped geometry to one K(1) and one Mg(1) atom.