MgCo2(SiO3)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 6-coordinate geometry to one O(10), one O(3), one O(4), one O(5), one O(6), and one O(9) atom. There are two inequivalent Co sites. In the first Co site, Co(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 CoO6 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 Co(2)O6 octahedra. In the second Co site, Co(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 distorted CoO6 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 Co(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 Co(2)O6 octahedra, corners with two equivalent Co(1)O6 octahedra, and corners with two equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-61°. 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 Co(2)O6 octahedra, corners with two equivalent Co(1)O6 octahedra, and corners with two equivalent Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-64°. 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 Co(1)O6 octahedra, corners with two equivalent Co(2)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-63°. 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 Co(1)O6 octahedra, corners with two equivalent Co(2)O6 octahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 38-63°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(3) atom. In the second O site, O(2) is bonded in a 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 distorted T-shaped geometry to one Mg(1), one Co(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Mg(1), one Co(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Co(2) and one Si(4) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Co(2) and one Si(3) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Mg(1), one Co(1), one Co(2), and one Si(3) atom. In the tenth O site, O(10) is bonded in a distorted tetrahedral geometry to one Mg(1), one Co(1), one Co(2), and one Si(4) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Co(1), one Co(2), and one Si(1) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal non-coplanar geometry to one Co(1), one Co(2), and one Si(2) atom.
MgCo2(SiO3)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a 6-coordinate geometry to one O(10), one O(3), one O(4), one O(5), one O(6), and one O(9) atom. The Mg(1)-O(10) bond length is 2.11 Å. The Mg(1)-O(3) bond length is 2.29 Å. The Mg(1)-O(4) bond length is 2.27 Å. The Mg(1)-O(5) bond length is 2.12 Å. The Mg(1)-O(6) bond length is 2.11 Å. The Mg(1)-O(9) bond length is 2.11 Å. There are two inequivalent Co sites. In the first Co site, Co(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 CoO6 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 Co(2)O6 octahedra. The Co(1)-O(10) bond length is 1.95 Å. The Co(1)-O(11) bond length is 1.98 Å. The Co(1)-O(12) bond length is 1.97 Å. The Co(1)-O(5) bond length is 1.94 Å. The Co(1)-O(6) bond length is 1.94 Å. The Co(1)-O(9) bond length is 1.96 Å. In the second Co site, Co(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 distorted CoO6 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 Co(1)O6 octahedra. The Co(2)-O(10) bond length is 2.20 Å. The Co(2)-O(11) bond length is 1.99 Å. The Co(2)-O(12) bond length is 2.05 Å. The Co(2)-O(7) bond length is 1.90 Å. The Co(2)-O(8) bond length is 1.83 Å. The Co(2)-O(9) bond length is 2.23 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 Co(2)O6 octahedra, corners with two equivalent Co(1)O6 octahedra, and corners with two equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-61°. The Si(1)-O(1) bond length is 1.63 Å. The Si(1)-O(11) bond length is 1.65 Å. The Si(1)-O(4) bond length is 1.67 Å. The Si(1)-O(5) bond length is 1.64 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 Co(2)O6 octahedra, corners with two equivalent Co(1)O6 octahedra, and corners with two equivalent Si(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-64°. The Si(2)-O(12) bond length is 1.65 Å. The Si(2)-O(2) bond length is 1.63 Å. The Si(2)-O(3) bond length is 1.67 Å. The Si(2)-O(6) bond length is 1.64 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 Co(1)O6 octahedra, corners with two equivalent Co(2)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 34-63°. The Si(3)-O(1) bond length is 1.63 Å. The Si(3)-O(4) bond length is 1.65 Å. The Si(3)-O(8) bond length is 1.61 Å. The Si(3)-O(9) bond length is 1.66 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 Co(1)O6 octahedra, corners with two equivalent Co(2)O6 octahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 38-63°. The Si(4)-O(10) bond length is 1.67 Å. The Si(4)-O(2) bond length is 1.64 Å. The Si(4)-O(3) bond length is 1.65 Å. The Si(4)-O(7) bond length is 1.59 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(3) atom. In the second O site, O(2) is bonded in a 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 distorted T-shaped geometry to one Mg(1), one Co(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Mg(1), one Co(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Co(2) and one Si(4) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Co(2) and one Si(3) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Mg(1), one Co(1), one Co(2), and one Si(3) atom. In the tenth O site, O(10) is bonded in a distorted tetrahedral geometry to one Mg(1), one Co(1), one Co(2), and one Si(4) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Co(1), one Co(2), and one Si(1) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal non-coplanar geometry to one Co(1), one Co(2), and one Si(2) atom.