MgGe4(BiO6)2 crystallizes in the monoclinic C2 space group. Mg(1) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(4) atoms. There are two inequivalent Ge sites. In the first Ge site, Ge(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form GeO4 tetrahedra that share  a cornercorner with one Bi(2)O6 octahedra, corners with two equivalent Bi(1)O6 octahedra, and corners with two equivalent Ge(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-55°. In the second Ge site, Ge(2) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form GeO4 tetrahedra that share  a cornercorner with one Bi(1)O6 octahedra, corners with two equivalent Bi(2)O6 octahedra, and corners with two equivalent Ge(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 43-60°. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms to form BiO6 octahedra that share corners with two equivalent Ge(2)O4 tetrahedra, corners with four equivalent Ge(1)O4 tetrahedra, and edges with two equivalent Bi(2)O6 octahedra. In the second Bi site, Bi(2) is bonded to two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms to form distorted BiO6 octahedra that share corners with two equivalent Ge(1)O4 tetrahedra, corners with four equivalent Ge(2)O4 tetrahedra, and edges with two equivalent Bi(1)O6 octahedra. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one Ge(1), and one Ge(2) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Ge(1) and one Ge(2) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Ge(2) and one Bi(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one Ge(1), and one Bi(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ge(1), one Bi(1), and one Bi(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ge(2), one Bi(1), and one Bi(2) atom.
MgGe4(BiO6)2 crystallizes in the monoclinic C2 space group. Mg(1) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(4) atoms. Both Mg(1)-O(1) bond lengths are 2.16 Å. Both Mg(1)-O(4) bond lengths are 2.06 Å. There are two inequivalent Ge sites. In the first Ge site, Ge(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form GeO4 tetrahedra that share  a cornercorner with one Bi(2)O6 octahedra, corners with two equivalent Bi(1)O6 octahedra, and corners with two equivalent Ge(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 46-55°. The Ge(1)-O(1) bond length is 1.82 Å. The Ge(1)-O(2) bond length is 1.79 Å. The Ge(1)-O(4) bond length is 1.78 Å. The Ge(1)-O(5) bond length is 1.75 Å. In the second Ge site, Ge(2) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form GeO4 tetrahedra that share  a cornercorner with one Bi(1)O6 octahedra, corners with two equivalent Bi(2)O6 octahedra, and corners with two equivalent Ge(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 43-60°. The Ge(2)-O(1) bond length is 1.83 Å. The Ge(2)-O(2) bond length is 1.81 Å. The Ge(2)-O(3) bond length is 1.72 Å. The Ge(2)-O(6) bond length is 1.76 Å. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms to form BiO6 octahedra that share corners with two equivalent Ge(2)O4 tetrahedra, corners with four equivalent Ge(1)O4 tetrahedra, and edges with two equivalent Bi(2)O6 octahedra. Both Bi(1)-O(4) bond lengths are 2.33 Å. Both Bi(1)-O(5) bond lengths are 2.45 Å. Both Bi(1)-O(6) bond lengths are 2.33 Å. In the second Bi site, Bi(2) is bonded to two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms to form distorted BiO6 octahedra that share corners with two equivalent Ge(1)O4 tetrahedra, corners with four equivalent Ge(2)O4 tetrahedra, and edges with two equivalent Bi(1)O6 octahedra. Both Bi(2)-O(3) bond lengths are 2.21 Å. Both Bi(2)-O(5) bond lengths are 2.41 Å. Both Bi(2)-O(6) bond lengths are 2.60 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one Ge(1), and one Ge(2) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Ge(1) and one Ge(2) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one Ge(2) and one Bi(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one Ge(1), and one Bi(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ge(1), one Bi(1), and one Bi(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ge(2), one Bi(1), and one Bi(2) atom.