MgSi4(MoO6)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 4-coordinate geometry to one O(3), one O(4), one O(7), and one O(8) atom. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one O(10), one O(11), one O(12), one O(5), one O(6), and one O(9) atom to form MoO6 octahedra that share  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and edges with two equivalent Mo(2)O6 octahedra. In the second Mo site, Mo(2) is bonded to one O(10), one O(11), one O(12), one O(7), one O(8), and one O(9) atom to form MoO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra, and edges with two equivalent Mo(1)O6 octahedra. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(11), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Mo(2)O6 octahedra, corners with two equivalent Mo(1)O6 octahedra, and corners with two equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 31-58°. In the second Si site, Si(2) is bonded to one O(12), one O(2), one O(3), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Mo(2)O6 octahedra, corners with two equivalent Mo(1)O6 octahedra, and corners with two equivalent Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 31-58°. In the third Si site, Si(3) is bonded to one O(1), one O(4), one O(8), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Mo(1)O6 octahedra, corners with two equivalent Mo(2)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 13-59°. In the fourth Si site, Si(4) is bonded to one O(10), one O(2), one O(3), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Mo(1)O6 octahedra, corners with two equivalent Mo(2)O6 octahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 12-59°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Si(1) and one Si(3) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Si(2) and one Si(4) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Mg(1), one Si(2), and one Si(4) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Mg(1), one Si(1), and one Si(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Mo(1) and one Si(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Mo(1) and one Si(2) atom. In the seventh O site, O(7) is bonded in a T-shaped geometry to one Mg(1), one Mo(2), and one Si(4) atom. In the eighth O site, O(8) is bonded in a T-shaped geometry to one Mg(1), one Mo(2), and one Si(3) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Mo(1), one Mo(2), and one Si(3) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one Mo(1), one Mo(2), and one Si(4) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Mo(1), one Mo(2), and one Si(1) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Mo(1), one Mo(2), and one Si(2) atom.
MgSi4(MoO6)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 4-coordinate geometry to one O(3), one O(4), one O(7), and one O(8) atom. The Mg(1)-O(3) bond length is 1.97 Å. The Mg(1)-O(4) bond length is 1.97 Å. The Mg(1)-O(7) bond length is 2.05 Å. The Mg(1)-O(8) bond length is 2.05 Å. There are two inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one O(10), one O(11), one O(12), one O(5), one O(6), and one O(9) atom to form MoO6 octahedra that share  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, and edges with two equivalent Mo(2)O6 octahedra. The Mo(1)-O(10) bond length is 2.16 Å. The Mo(1)-O(11) bond length is 2.25 Å. The Mo(1)-O(12) bond length is 2.25 Å. The Mo(1)-O(5) bond length is 2.12 Å. The Mo(1)-O(6) bond length is 2.12 Å. The Mo(1)-O(9) bond length is 2.16 Å. In the second Mo site, Mo(2) is bonded to one O(10), one O(11), one O(12), one O(7), one O(8), and one O(9) atom to form MoO6 octahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with two equivalent Si(4)O4 tetrahedra, and edges with two equivalent Mo(1)O6 octahedra. The Mo(2)-O(10) bond length is 2.18 Å. The Mo(2)-O(11) bond length is 2.16 Å. The Mo(2)-O(12) bond length is 2.16 Å. The Mo(2)-O(7) bond length is 2.17 Å. The Mo(2)-O(8) bond length is 2.17 Å. The Mo(2)-O(9) bond length is 2.18 Å. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(11), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Mo(2)O6 octahedra, corners with two equivalent Mo(1)O6 octahedra, and corners with two equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 31-58°. The Si(1)-O(1) bond length is 1.67 Å. The Si(1)-O(11) bond length is 1.65 Å. The Si(1)-O(4) bond length is 1.69 Å. The Si(1)-O(5) bond length is 1.59 Å. In the second Si site, Si(2) is bonded to one O(12), one O(2), one O(3), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Mo(2)O6 octahedra, corners with two equivalent Mo(1)O6 octahedra, and corners with two equivalent Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 31-58°. The Si(2)-O(12) bond length is 1.65 Å. The Si(2)-O(2) bond length is 1.67 Å. The Si(2)-O(3) bond length is 1.69 Å. The Si(2)-O(6) bond length is 1.59 Å. In the third Si site, Si(3) is bonded to one O(1), one O(4), one O(8), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Mo(1)O6 octahedra, corners with two equivalent Mo(2)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 13-59°. The Si(3)-O(1) bond length is 1.65 Å. The Si(3)-O(4) bond length is 1.72 Å. The Si(3)-O(8) bond length is 1.63 Å. The Si(3)-O(9) bond length is 1.61 Å. In the fourth Si site, Si(4) is bonded to one O(10), one O(2), one O(3), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Mo(1)O6 octahedra, corners with two equivalent Mo(2)O6 octahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 12-59°. The Si(4)-O(10) bond length is 1.61 Å. The Si(4)-O(2) bond length is 1.65 Å. The Si(4)-O(3) bond length is 1.72 Å. The Si(4)-O(7) bond length is 1.63 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Si(1) and one Si(3) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Si(2) and one Si(4) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Mg(1), one Si(2), and one Si(4) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Mg(1), one Si(1), and one Si(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Mo(1) and one Si(1) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Mo(1) and one Si(2) atom. In the seventh O site, O(7) is bonded in a T-shaped geometry to one Mg(1), one Mo(2), and one Si(4) atom. In the eighth O site, O(8) is bonded in a T-shaped geometry to one Mg(1), one Mo(2), and one Si(3) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Mo(1), one Mo(2), and one Si(3) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one Mo(1), one Mo(2), and one Si(4) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Mo(1), one Mo(2), and one Si(1) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Mo(1), one Mo(2), and one Si(2) atom.