Mg2TaBiO6 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(3), one O(4), and two equivalent O(1) atoms to form distorted MgO4 trigonal pyramids that share corners with four equivalent Ta(1)O6 octahedra, corners with four equivalent Bi(1)O6 octahedra, and corners with two equivalent Mg(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-84°. In the second Mg site, Mg(2) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form distorted MgO4 tetrahedra that share corners with four equivalent Ta(1)O6 octahedra, corners with four equivalent Bi(1)O6 octahedra, and corners with two equivalent Mg(1)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 58-80°. Ta(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with four equivalent Bi(1)O6 octahedra, corners with four equivalent Mg(2)O4 tetrahedra, and corners with four equivalent Mg(1)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 47-54°. Bi(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form BiO6 octahedra that share corners with two equivalent Bi(1)O6 octahedra, corners with four equivalent Ta(1)O6 octahedra, corners with four equivalent Mg(2)O4 tetrahedra, and corners with four equivalent Mg(1)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 47-58°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1), one Ta(1), and one Bi(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mg(2), one Ta(1), and one Bi(1) atom. In the third O site, O(3) is bonded to one Mg(1), one Mg(2), and two equivalent Ta(1) atoms to form distorted OMg2Ta2 tetrahedra that share corners with two equivalent O(4)Mg2Bi2 tetrahedra and corners with two equivalent O(3)Mg2Ta2 tetrahedra. In the fourth O site, O(4) is bonded to one Mg(1), one Mg(2), and two equivalent Bi(1) atoms to form distorted OMg2Bi2 tetrahedra that share corners with two equivalent O(4)Mg2Bi2 tetrahedra and corners with two equivalent O(3)Mg2Ta2 tetrahedra.
Mg2TaBiO6 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one O(3), one O(4), and two equivalent O(1) atoms to form distorted MgO4 trigonal pyramids that share corners with four equivalent Ta(1)O6 octahedra, corners with four equivalent Bi(1)O6 octahedra, and corners with two equivalent Mg(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 54-84°. The Mg(1)-O(3) bond length is 2.24 Å. The Mg(1)-O(4) bond length is 2.02 Å. Both Mg(1)-O(1) bond lengths are 2.05 Å. In the second Mg site, Mg(2) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form distorted MgO4 tetrahedra that share corners with four equivalent Ta(1)O6 octahedra, corners with four equivalent Bi(1)O6 octahedra, and corners with two equivalent Mg(1)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 58-80°. The Mg(2)-O(3) bond length is 2.10 Å. The Mg(2)-O(4) bond length is 2.03 Å. Both Mg(2)-O(2) bond lengths are 2.04 Å. Ta(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with four equivalent Bi(1)O6 octahedra, corners with four equivalent Mg(2)O4 tetrahedra, and corners with four equivalent Mg(1)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 47-54°. Both Ta(1)-O(1) bond lengths are 1.96 Å. Both Ta(1)-O(2) bond lengths are 1.99 Å. Both Ta(1)-O(3) bond lengths are 2.18 Å. Bi(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form BiO6 octahedra that share corners with two equivalent Bi(1)O6 octahedra, corners with four equivalent Ta(1)O6 octahedra, corners with four equivalent Mg(2)O4 tetrahedra, and corners with four equivalent Mg(1)O4 trigonal pyramids. The corner-sharing octahedral tilt angles range from 47-58°. Both Bi(1)-O(1) bond lengths are 2.35 Å. Both Bi(1)-O(2) bond lengths are 2.44 Å. Both Bi(1)-O(4) bond lengths are 2.29 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1), one Ta(1), and one Bi(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Mg(2), one Ta(1), and one Bi(1) atom. In the third O site, O(3) is bonded to one Mg(1), one Mg(2), and two equivalent Ta(1) atoms to form distorted OMg2Ta2 tetrahedra that share corners with two equivalent O(4)Mg2Bi2 tetrahedra and corners with two equivalent O(3)Mg2Ta2 tetrahedra. In the fourth O site, O(4) is bonded to one Mg(1), one Mg(2), and two equivalent Bi(1) atoms to form distorted OMg2Bi2 tetrahedra that share corners with two equivalent O(4)Mg2Bi2 tetrahedra and corners with two equivalent O(3)Mg2Ta2 tetrahedra.