CsMgNb(PO4)2 crystallizes in the triclinic P1 space group. Cs(1) is bonded in a 6-coordinate geometry to one O(1), one O(4), one O(5), and three equivalent O(3) atoms. Mg(1) is bonded in a rectangular see-saw-like geometry to one O(5), one O(6), one O(7), and one O(8) atom. Nb(1) is bonded to one O(1), one O(2), one O(4), one O(6), one O(7), and one O(8) atom to form distorted NbO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with three equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-49°. In the second P site, P(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with three equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 29-39°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Cs(1), one Nb(1), and one P(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to three equivalent Cs(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Cs(1), one Nb(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted L-shaped geometry to one Cs(1), one Mg(1), and one P(1) atom. In the sixth O site, O(6) is bonded in a T-shaped geometry to one Mg(1), one Nb(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Mg(1), one Nb(1), and one P(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Mg(1), one Nb(1), and one P(1) atom.
CsMgNb(PO4)2 crystallizes in the triclinic P1 space group. Cs(1) is bonded in a 6-coordinate geometry to one O(1), one O(4), one O(5), and three equivalent O(3) atoms. The Cs(1)-O(1) bond length is 3.02 Å. The Cs(1)-O(4) bond length is 2.96 Å. The Cs(1)-O(5) bond length is 3.73 Å. There are a spread of Cs(1)-O(3) bond distances ranging from 2.93-3.38 Å. Mg(1) is bonded in a rectangular see-saw-like geometry to one O(5), one O(6), one O(7), and one O(8) atom. The Mg(1)-O(5) bond length is 1.99 Å. The Mg(1)-O(6) bond length is 2.11 Å. The Mg(1)-O(7) bond length is 1.97 Å. The Mg(1)-O(8) bond length is 1.95 Å. Nb(1) is bonded to one O(1), one O(2), one O(4), one O(6), one O(7), and one O(8) atom to form distorted NbO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. The Nb(1)-O(1) bond length is 2.10 Å. The Nb(1)-O(2) bond length is 2.01 Å. The Nb(1)-O(4) bond length is 2.02 Å. The Nb(1)-O(6) bond length is 2.24 Å. The Nb(1)-O(7) bond length is 2.36 Å. The Nb(1)-O(8) bond length is 2.45 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with three equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-49°. The P(1)-O(5) bond length is 1.57 Å. The P(1)-O(6) bond length is 1.55 Å. The P(1)-O(7) bond length is 1.56 Å. The P(1)-O(8) bond length is 1.55 Å. In the second P site, P(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with three equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 29-39°. The P(2)-O(1) bond length is 1.55 Å. The P(2)-O(2) bond length is 1.56 Å. The P(2)-O(3) bond length is 1.52 Å. The P(2)-O(4) bond length is 1.57 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Cs(1), one Nb(1), and one P(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to three equivalent Cs(1) and one P(2) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one Cs(1), one Nb(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a distorted L-shaped geometry to one Cs(1), one Mg(1), and one P(1) atom. In the sixth O site, O(6) is bonded in a T-shaped geometry to one Mg(1), one Nb(1), and one P(1) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Mg(1), one Nb(1), and one P(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Mg(1), one Nb(1), and one P(1) atom.