MgW3P4O14 crystallizes in the monoclinic P2_1/c space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted MgO6 octahedra that share corners with four equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 trigonal pyramids, and edges with two equivalent W(1)O6 octahedra. There are two inequivalent W sites. In the first W site, W(1) is bonded to one O(2), one O(3), one O(5), one O(6), and two equivalent O(7) atoms to form WO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 trigonal pyramids,  an edgeedge with one Mg(1)O6 octahedra, and  an edgeedge with one W(1)O6 octahedra. In the second W site, W(2) is bonded in a distorted square co-planar geometry to two equivalent O(1) and two equivalent O(6) atoms. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with three equivalent W(1)O6 octahedra, and  a cornercorner with one P(2)O4 trigonal pyramid. The corner-sharing octahedral tilt angles range from 39-63°. In the second P site, P(2) is bonded to one O(1), one O(4), one O(6), and one O(7) atom to form PO4 trigonal pyramids that share  a cornercorner with one Mg(1)O6 octahedra, corners with three equivalent W(1)O6 octahedra, and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-70°. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a distorted bent 150 degrees geometry to one W(1) and one P(1) atom. In the second O site, O(6) is bonded in a 3-coordinate geometry to one W(1), one W(2), and one P(2) atom. In the third O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to two equivalent W(1) and one P(2) atom. In the fourth O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one W(2), and one P(2) atom. In the fifth O site, O(2) is bonded in a 2-coordinate geometry to one Mg(1), one W(1), and one P(1) atom. In the sixth O site, O(3) is bonded in a 3-coordinate geometry to one Mg(1), one W(1), and one P(1) atom. In the seventh O site, O(4) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom.
MgW3P4O14 crystallizes in the monoclinic P2_1/c space group. Mg(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form distorted MgO6 octahedra that share corners with four equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 trigonal pyramids, and edges with two equivalent W(1)O6 octahedra. Both Mg(1)-O(1) bond lengths are 2.20 Å. Both Mg(1)-O(2) bond lengths are 2.05 Å. Both Mg(1)-O(3) bond lengths are 2.57 Å. There are two inequivalent W sites. In the first W site, W(1) is bonded to one O(2), one O(3), one O(5), one O(6), and two equivalent O(7) atoms to form WO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 trigonal pyramids,  an edgeedge with one Mg(1)O6 octahedra, and  an edgeedge with one W(1)O6 octahedra. The W(1)-O(2) bond length is 2.34 Å. The W(1)-O(3) bond length is 2.17 Å. The W(1)-O(5) bond length is 2.10 Å. The W(1)-O(6) bond length is 2.22 Å. There is one shorter (2.13 Å) and one longer (2.21 Å) W(1)-O(7) bond length. In the second W site, W(2) is bonded in a distorted square co-planar geometry to two equivalent O(1) and two equivalent O(6) atoms. Both W(2)-O(1) bond lengths are 2.30 Å. Both W(2)-O(6) bond lengths are 2.20 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra, corners with three equivalent W(1)O6 octahedra, and  a cornercorner with one P(2)O4 trigonal pyramid. The corner-sharing octahedral tilt angles range from 39-63°. The P(1)-O(2) bond length is 1.57 Å. The P(1)-O(3) bond length is 1.55 Å. The P(1)-O(4) bond length is 1.58 Å. The P(1)-O(5) bond length is 1.52 Å. In the second P site, P(2) is bonded to one O(1), one O(4), one O(6), and one O(7) atom to form PO4 trigonal pyramids that share  a cornercorner with one Mg(1)O6 octahedra, corners with three equivalent W(1)O6 octahedra, and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-70°. The P(2)-O(1) bond length is 1.58 Å. The P(2)-O(4) bond length is 1.75 Å. The P(2)-O(6) bond length is 1.59 Å. The P(2)-O(7) bond length is 1.58 Å. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a distorted bent 150 degrees geometry to one W(1) and one P(1) atom. In the second O site, O(6) is bonded in a 3-coordinate geometry to one W(1), one W(2), and one P(2) atom. In the third O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to two equivalent W(1) and one P(2) atom. In the fourth O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one W(2), and one P(2) atom. In the fifth O site, O(2) is bonded in a 2-coordinate geometry to one Mg(1), one W(1), and one P(1) atom. In the sixth O site, O(3) is bonded in a 3-coordinate geometry to one Mg(1), one W(1), and one P(1) atom. In the seventh O site, O(4) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom.