MgTi3CuO8 crystallizes in the orthorhombic Pmm2 space group. Mg(1) is bonded in a 5-coordinate geometry to one O(5), two equivalent O(1), and two equivalent O(7) atoms. There are three inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(8), two equivalent O(4), and two equivalent O(6) atoms to form a mixture of distorted edge and corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 14-27°. In the second Ti site, Ti(2) is bonded to one O(3), one O(6), two equivalent O(1), and two equivalent O(7) atoms to form TiO6 octahedra that share corners with four equivalent Ti(2)O6 octahedra, corners with two equivalent Cu(1)O5 trigonal bipyramids, and edges with two equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-11°. In the third Ti site, Ti(3) is bonded to one O(4), one O(5), two equivalent O(2), and two equivalent O(8) atoms to form TiO6 octahedra that share corners with four equivalent Ti(3)O6 octahedra, edges with two equivalent Ti(1)O6 octahedra, and edges with two equivalent Cu(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 7-25°. Cu(1) is bonded to one O(2), two equivalent O(3), and two equivalent O(5) atoms to form CuO5 trigonal bipyramids that share corners with two equivalent Ti(2)O6 octahedra, corners with four equivalent Cu(1)O5 trigonal bipyramids, and edges with two equivalent Ti(3)O6 octahedra. The corner-sharing octahedral tilt angles are 62°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1), one Ti(1), and two equivalent Ti(2) atoms to form corner-sharing OMg2Ti3 trigonal bipyramids. In the second O site, O(2) is bonded in a T-shaped geometry to two equivalent Ti(3) and one Cu(1) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Ti(2) and two equivalent Cu(1) atoms. In the fourth O site, O(4) is bonded in a T-shaped geometry to one Ti(3) and two equivalent Ti(1) atoms. In the fifth O site, O(5) is bonded in a square co-planar geometry to one Mg(1), one Ti(3), and two equivalent Cu(1) atoms. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Ti(2) and two equivalent Ti(1) atoms. In the seventh O site, O(7) is bonded in a see-saw-like geometry to two equivalent Mg(1) and two equivalent Ti(2) atoms. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Ti(1) and two equivalent Ti(3) atoms.
MgTi3CuO8 crystallizes in the orthorhombic Pmm2 space group. Mg(1) is bonded in a 5-coordinate geometry to one O(5), two equivalent O(1), and two equivalent O(7) atoms. The Mg(1)-O(5) bond length is 2.05 Å. Both Mg(1)-O(1) bond lengths are 2.27 Å. Both Mg(1)-O(7) bond lengths are 2.11 Å. There are three inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(8), two equivalent O(4), and two equivalent O(6) atoms to form a mixture of distorted edge and corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 14-27°. The Ti(1)-O(1) bond length is 2.29 Å. The Ti(1)-O(8) bond length is 1.88 Å. Both Ti(1)-O(4) bond lengths are 1.95 Å. Both Ti(1)-O(6) bond lengths are 2.00 Å. In the second Ti site, Ti(2) is bonded to one O(3), one O(6), two equivalent O(1), and two equivalent O(7) atoms to form TiO6 octahedra that share corners with four equivalent Ti(2)O6 octahedra, corners with two equivalent Cu(1)O5 trigonal bipyramids, and edges with two equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 10-11°. The Ti(2)-O(3) bond length is 1.88 Å. The Ti(2)-O(6) bond length is 2.02 Å. Both Ti(2)-O(1) bond lengths are 1.95 Å. Both Ti(2)-O(7) bond lengths are 1.95 Å. In the third Ti site, Ti(3) is bonded to one O(4), one O(5), two equivalent O(2), and two equivalent O(8) atoms to form TiO6 octahedra that share corners with four equivalent Ti(3)O6 octahedra, edges with two equivalent Ti(1)O6 octahedra, and edges with two equivalent Cu(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 7-25°. The Ti(3)-O(4) bond length is 2.07 Å. The Ti(3)-O(5) bond length is 1.97 Å. Both Ti(3)-O(2) bond lengths are 1.95 Å. Both Ti(3)-O(8) bond lengths are 1.99 Å. Cu(1) is bonded to one O(2), two equivalent O(3), and two equivalent O(5) atoms to form CuO5 trigonal bipyramids that share corners with two equivalent Ti(2)O6 octahedra, corners with four equivalent Cu(1)O5 trigonal bipyramids, and edges with two equivalent Ti(3)O6 octahedra. The corner-sharing octahedral tilt angles are 62°. The Cu(1)-O(2) bond length is 1.97 Å. Both Cu(1)-O(3) bond lengths are 2.21 Å. Both Cu(1)-O(5) bond lengths are 1.95 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1), one Ti(1), and two equivalent Ti(2) atoms to form corner-sharing OMg2Ti3 trigonal bipyramids. In the second O site, O(2) is bonded in a T-shaped geometry to two equivalent Ti(3) and one Cu(1) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Ti(2) and two equivalent Cu(1) atoms. In the fourth O site, O(4) is bonded in a T-shaped geometry to one Ti(3) and two equivalent Ti(1) atoms. In the fifth O site, O(5) is bonded in a square co-planar geometry to one Mg(1), one Ti(3), and two equivalent Cu(1) atoms. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Ti(2) and two equivalent Ti(1) atoms. In the seventh O site, O(7) is bonded in a see-saw-like geometry to two equivalent Mg(1) and two equivalent Ti(2) atoms. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Ti(1) and two equivalent Ti(3) atoms.