Na4MgTi2(SiO5)2 crystallizes in the monoclinic Pm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 4-coordinate geometry to one O(1), one O(3), one O(6), and one O(8) atom. In the second Na site, Na(2) is bonded to one O(1), one O(4), one O(5), one O(6), and one O(7) atom to form NaO5 square pyramids that share  a cornercorner with one Na(2)O5 square pyramid, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  a cornercorner with one Ti(1)O5 trigonal bipyramid,  an edgeedge with one Na(2)O5 square pyramid,  an edgeedge with one Ti(1)O5 trigonal bipyramid, and  an edgeedge with one Ti(2)O5 trigonal bipyramid. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one O(2), one O(8), and two equivalent O(5) atoms. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(3), one O(4), and two equivalent O(5) atoms to form distorted TiO5 trigonal bipyramids that share corners with two equivalent Na(2)O5 square pyramids, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and edges with two equivalent Na(2)O5 square pyramids. In the second Ti site, Ti(2) is bonded to one O(2), one O(7), one O(8), and two equivalent O(6) atoms to form distorted TiO5 trigonal bipyramids that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and edges with two equivalent Na(2)O5 square pyramids. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(7), one O(8), and two equivalent O(5) atoms to form SiO4 tetrahedra that share corners with four equivalent Na(2)O5 square pyramids, corners with two equivalent Ti(1)O5 trigonal bipyramids, and corners with two equivalent Ti(2)O5 trigonal bipyramids. In the second Si site, Si(2) is bonded to one O(3), one O(4), and two equivalent O(6) atoms to form SiO4 tetrahedra that share corners with four equivalent Na(2)O5 square pyramids, corners with two equivalent Ti(1)O5 trigonal bipyramids, and corners with two equivalent Ti(2)O5 trigonal bipyramids. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and one Ti(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Mg(1) and one Ti(2) atom. In the third O site, O(3) is bonded in a distorted tetrahedral geometry to two equivalent Na(1), one Ti(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to two equivalent Na(2), one Ti(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Na(2), one Mg(1), one Ti(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(2), one Ti(2), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted tetrahedral geometry to two equivalent Na(2), one Ti(2), and one Si(1) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to two equivalent Na(1), one Mg(1), one Ti(2), and one Si(1) atom.
Na4MgTi2(SiO5)2 crystallizes in the monoclinic Pm space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 4-coordinate geometry to one O(1), one O(3), one O(6), and one O(8) atom. The Na(1)-O(1) bond length is 2.34 Å. The Na(1)-O(3) bond length is 2.27 Å. The Na(1)-O(6) bond length is 2.18 Å. The Na(1)-O(8) bond length is 2.43 Å. In the second Na site, Na(2) is bonded to one O(1), one O(4), one O(5), one O(6), and one O(7) atom to form NaO5 square pyramids that share  a cornercorner with one Na(2)O5 square pyramid, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra,  a cornercorner with one Ti(1)O5 trigonal bipyramid,  an edgeedge with one Na(2)O5 square pyramid,  an edgeedge with one Ti(1)O5 trigonal bipyramid, and  an edgeedge with one Ti(2)O5 trigonal bipyramid. The Na(2)-O(1) bond length is 2.57 Å. The Na(2)-O(4) bond length is 2.28 Å. The Na(2)-O(5) bond length is 2.53 Å. The Na(2)-O(6) bond length is 2.31 Å. The Na(2)-O(7) bond length is 2.34 Å. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one O(2), one O(8), and two equivalent O(5) atoms. The Mg(1)-O(2) bond length is 1.95 Å. The Mg(1)-O(8) bond length is 1.97 Å. Both Mg(1)-O(5) bond lengths are 2.00 Å. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(3), one O(4), and two equivalent O(5) atoms to form distorted TiO5 trigonal bipyramids that share corners with two equivalent Na(2)O5 square pyramids, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and edges with two equivalent Na(2)O5 square pyramids. The Ti(1)-O(1) bond length is 1.78 Å. The Ti(1)-O(3) bond length is 2.12 Å. The Ti(1)-O(4) bond length is 2.11 Å. Both Ti(1)-O(5) bond lengths are 2.22 Å. In the second Ti site, Ti(2) is bonded to one O(2), one O(7), one O(8), and two equivalent O(6) atoms to form distorted TiO5 trigonal bipyramids that share corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and edges with two equivalent Na(2)O5 square pyramids. The Ti(2)-O(2) bond length is 1.80 Å. The Ti(2)-O(7) bond length is 2.08 Å. The Ti(2)-O(8) bond length is 2.36 Å. Both Ti(2)-O(6) bond lengths are 2.13 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(7), one O(8), and two equivalent O(5) atoms to form SiO4 tetrahedra that share corners with four equivalent Na(2)O5 square pyramids, corners with two equivalent Ti(1)O5 trigonal bipyramids, and corners with two equivalent Ti(2)O5 trigonal bipyramids. The Si(1)-O(7) bond length is 1.62 Å. The Si(1)-O(8) bond length is 1.68 Å. Both Si(1)-O(5) bond lengths are 1.67 Å. In the second Si site, Si(2) is bonded to one O(3), one O(4), and two equivalent O(6) atoms to form SiO4 tetrahedra that share corners with four equivalent Na(2)O5 square pyramids, corners with two equivalent Ti(1)O5 trigonal bipyramids, and corners with two equivalent Ti(2)O5 trigonal bipyramids. The Si(2)-O(3) bond length is 1.67 Å. The Si(2)-O(4) bond length is 1.66 Å. Both Si(2)-O(6) bond lengths are 1.66 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and one Ti(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Mg(1) and one Ti(2) atom. In the third O site, O(3) is bonded in a distorted tetrahedral geometry to two equivalent Na(1), one Ti(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to two equivalent Na(2), one Ti(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Na(2), one Mg(1), one Ti(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(2), one Ti(2), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted tetrahedral geometry to two equivalent Na(2), one Ti(2), and one Si(1) atom. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to two equivalent Na(1), one Mg(1), one Ti(2), and one Si(1) atom.