Na3MgCPO7 crystallizes in the monoclinic P2_1 space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form NaO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, edges with two equivalent Na(1)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. In the second Na site, Na(2) is bonded in a 3-coordinate geometry to one O(1), one O(2), one O(3), and one O(6) atom. In the third Na site, Na(3) is bonded to two equivalent O(5), two equivalent O(6), and two equivalent O(7) atoms to form distorted NaO6 octahedra that share corners with four equivalent P(1)O4 tetrahedra, corners with four equivalent Mg(1)O5 trigonal bipyramids, and faces with two equivalent Na(3)O6 octahedra. Mg(1) is bonded to one O(2), one O(3), one O(4), one O(5), and one O(7) atom to form distorted MgO5 trigonal bipyramids that share corners with four equivalent Na(3)O6 octahedra, corners with three equivalent P(1)O4 tetrahedra, and edges with two equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 71-83°. C(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(5) atom. P(1) is bonded to one O(3), one O(4), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Na(1)O6 octahedra, corners with four equivalent Na(3)O6 octahedra, and corners with three equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 52-69°. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(1), and one C(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(2), two equivalent Na(1), one Mg(1), and one C(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Mg(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Mg(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent Na(3), one Mg(1), and one C(1) atom. In the sixth O site, O(6) is bonded to one Na(2), two equivalent Na(3), and one P(1) atom to form distorted corner-sharing ONa3P tetrahedra. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to two equivalent Na(3), one Mg(1), and one P(1) atom.
Na3MgCPO7 crystallizes in the monoclinic P2_1 space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form NaO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, edges with two equivalent Na(1)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The Na(1)-O(3) bond length is 2.40 Å. The Na(1)-O(4) bond length is 2.30 Å. There is one shorter (2.40 Å) and one longer (2.41 Å) Na(1)-O(1) bond length. There is one shorter (2.40 Å) and one longer (2.46 Å) Na(1)-O(2) bond length. In the second Na site, Na(2) is bonded in a 3-coordinate geometry to one O(1), one O(2), one O(3), and one O(6) atom. The Na(2)-O(1) bond length is 2.31 Å. The Na(2)-O(2) bond length is 2.78 Å. The Na(2)-O(3) bond length is 2.34 Å. The Na(2)-O(6) bond length is 2.23 Å. In the third Na site, Na(3) is bonded to two equivalent O(5), two equivalent O(6), and two equivalent O(7) atoms to form distorted NaO6 octahedra that share corners with four equivalent P(1)O4 tetrahedra, corners with four equivalent Mg(1)O5 trigonal bipyramids, and faces with two equivalent Na(3)O6 octahedra. There is one shorter (2.47 Å) and one longer (2.62 Å) Na(3)-O(5) bond length. There is one shorter (2.26 Å) and one longer (2.27 Å) Na(3)-O(6) bond length. There is one shorter (2.56 Å) and one longer (2.65 Å) Na(3)-O(7) bond length. Mg(1) is bonded to one O(2), one O(3), one O(4), one O(5), and one O(7) atom to form distorted MgO5 trigonal bipyramids that share corners with four equivalent Na(3)O6 octahedra, corners with three equivalent P(1)O4 tetrahedra, and edges with two equivalent Na(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 71-83°. The Mg(1)-O(2) bond length is 2.19 Å. The Mg(1)-O(3) bond length is 2.10 Å. The Mg(1)-O(4) bond length is 2.07 Å. The Mg(1)-O(5) bond length is 2.15 Å. The Mg(1)-O(7) bond length is 2.01 Å. C(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(5) atom. The C(1)-O(1) bond length is 1.30 Å. The C(1)-O(2) bond length is 1.32 Å. The C(1)-O(5) bond length is 1.29 Å. P(1) is bonded to one O(3), one O(4), one O(6), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Na(1)O6 octahedra, corners with four equivalent Na(3)O6 octahedra, and corners with three equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 52-69°. The P(1)-O(3) bond length is 1.57 Å. The P(1)-O(4) bond length is 1.56 Å. The P(1)-O(6) bond length is 1.54 Å. The P(1)-O(7) bond length is 1.56 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Na(2), two equivalent Na(1), and one C(1) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(2), two equivalent Na(1), one Mg(1), and one C(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Mg(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Mg(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent Na(3), one Mg(1), and one C(1) atom. In the sixth O site, O(6) is bonded to one Na(2), two equivalent Na(3), and one P(1) atom to form distorted corner-sharing ONa3P tetrahedra. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to two equivalent Na(3), one Mg(1), and one P(1) atom.