MgNb2(PO5)2 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form MgO6 octahedra that share corners with four equivalent P(1)O4 tetrahedra. Nb(1) is bonded in a 5-coordinate geometry to one O(3), two equivalent O(1), and two equivalent O(2) atoms. P(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 55°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one Nb(1), and one P(1) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Mg(1) and one Nb(1) atom.
MgNb2(PO5)2 crystallizes in the monoclinic C2/m space group. Mg(1) is bonded to two equivalent O(3) and four equivalent O(2) atoms to form MgO6 octahedra that share corners with four equivalent P(1)O4 tetrahedra. Both Mg(1)-O(3) bond lengths are 2.14 Å. All Mg(1)-O(2) bond lengths are 2.06 Å. Nb(1) is bonded in a 5-coordinate geometry to one O(3), two equivalent O(1), and two equivalent O(2) atoms. The Nb(1)-O(3) bond length is 1.80 Å. Both Nb(1)-O(1) bond lengths are 2.07 Å. Both Nb(1)-O(2) bond lengths are 2.20 Å. P(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 55°. Both P(1)-O(1) bond lengths are 1.53 Å. Both P(1)-O(2) bond lengths are 1.57 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Nb(1) and one P(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one Nb(1), and one P(1) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Mg(1) and one Nb(1) atom.