MgCeTi2O6 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(3), one O(4), one O(5), one O(6), and two equivalent O(2) atoms to form distorted MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra and edges with three equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles are 6°. Ce(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(6), and two equivalent O(5) atoms. In the second Ti site, Ti(2) is bonded to one O(1), one O(2), one O(4), one O(5), and two equivalent O(6) atoms to form TiO6 octahedra that share corners with two equivalent Ti(2)O6 octahedra and edges with three equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 7°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Ce(1), one Ti(1), and one Ti(2) atom. In the second O site, O(2) is bonded to two equivalent Mg(1), one Ce(1), one Ti(1), and one Ti(2) atom to form distorted OCeMg2Ti2 trigonal bipyramids that share corners with two equivalent O(2)CeMg2Ti2 trigonal bipyramids,  a cornercorner with one O(4)Ce2MgTi trigonal pyramid, and edges with two equivalent O(4)Ce2MgTi trigonal pyramids. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Mg(1), two equivalent Ce(1), and one Ti(1) atom. In the fourth O site, O(4) is bonded to one Mg(1), two equivalent Ce(1), and one Ti(2) atom to form OCe2MgTi trigonal pyramids that share  a cornercorner with one O(2)CeMg2Ti2 trigonal bipyramid, corners with two equivalent O(4)Ce2MgTi trigonal pyramids, and edges with two equivalent O(2)CeMg2Ti2 trigonal bipyramids. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Ti(2), and two equivalent Ti(1) atoms. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Ti(1), and two equivalent Ti(2) atoms.
MgCeTi2O6 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(3), one O(4), one O(5), one O(6), and two equivalent O(2) atoms to form distorted MgO6 octahedra that share corners with two equivalent Mg(1)O6 octahedra and edges with three equivalent Ti(2)O6 octahedra. The corner-sharing octahedral tilt angles are 6°. The Mg(1)-O(3) bond length is 2.61 Å. The Mg(1)-O(4) bond length is 2.15 Å. The Mg(1)-O(5) bond length is 2.09 Å. The Mg(1)-O(6) bond length is 2.09 Å. Both Mg(1)-O(2) bond lengths are 2.02 Å. Ce(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms. The Ce(1)-O(1) bond length is 2.24 Å. The Ce(1)-O(2) bond length is 2.37 Å. Both Ce(1)-O(3) bond lengths are 2.65 Å. Both Ce(1)-O(4) bond lengths are 2.32 Å. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(6), and two equivalent O(5) atoms. The Ti(1)-O(1) bond length is 2.00 Å. The Ti(1)-O(2) bond length is 2.52 Å. The Ti(1)-O(3) bond length is 1.81 Å. The Ti(1)-O(6) bond length is 2.15 Å. Both Ti(1)-O(5) bond lengths are 2.05 Å. In the second Ti site, Ti(2) is bonded to one O(1), one O(2), one O(4), one O(5), and two equivalent O(6) atoms to form TiO6 octahedra that share corners with two equivalent Ti(2)O6 octahedra and edges with three equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 7°. The Ti(2)-O(1) bond length is 1.94 Å. The Ti(2)-O(2) bond length is 2.11 Å. The Ti(2)-O(4) bond length is 1.99 Å. The Ti(2)-O(5) bond length is 2.02 Å. Both Ti(2)-O(6) bond lengths are 2.02 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Ce(1), one Ti(1), and one Ti(2) atom. In the second O site, O(2) is bonded to two equivalent Mg(1), one Ce(1), one Ti(1), and one Ti(2) atom to form distorted OCeMg2Ti2 trigonal bipyramids that share corners with two equivalent O(2)CeMg2Ti2 trigonal bipyramids,  a cornercorner with one O(4)Ce2MgTi trigonal pyramid, and edges with two equivalent O(4)Ce2MgTi trigonal pyramids. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Mg(1), two equivalent Ce(1), and one Ti(1) atom. In the fourth O site, O(4) is bonded to one Mg(1), two equivalent Ce(1), and one Ti(2) atom to form OCe2MgTi trigonal pyramids that share  a cornercorner with one O(2)CeMg2Ti2 trigonal bipyramid, corners with two equivalent O(4)Ce2MgTi trigonal pyramids, and edges with two equivalent O(2)CeMg2Ti2 trigonal bipyramids. In the fifth O site, O(5) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Ti(2), and two equivalent Ti(1) atoms. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Ti(1), and two equivalent Ti(2) atoms.