MgCo2(GeO3)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(10), one O(3), one O(4), one O(5), one O(6), and one O(9) atom to form distorted MgO6 pentagonal pyramids that share corners with two equivalent Ge(1)O4 tetrahedra, corners with two equivalent Ge(2)O4 tetrahedra,  an edgeedge with one Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra,  an edgeedge with one Ge(3)O4 tetrahedra, and  an edgeedge with one Ge(4)O4 tetrahedra. 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(7), one O(8), and one O(9) atom to form distorted CoO6 octahedra that share  a cornercorner with one Ge(3)O4 tetrahedra,  a cornercorner with one Ge(4)O4 tetrahedra, corners with two equivalent Ge(1)O4 tetrahedra, corners with two equivalent Ge(2)O4 tetrahedra, edges with two equivalent Co(2)O6 octahedra, and  an edgeedge with one Mg(1)O6 pentagonal pyramid. In the second Co site, Co(2) 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 Ge(1)O4 tetrahedra,  a cornercorner with one Ge(2)O4 tetrahedra, corners with two equivalent Ge(3)O4 tetrahedra, corners with two equivalent Ge(4)O4 tetrahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Mg(1)O6 pentagonal pyramids. There are four inequivalent Ge sites. In the first Ge site, Ge(1) is bonded to one O(1), one O(4), one O(8), and one O(9) atom to form GeO4 tetrahedra that share  a cornercorner with one Co(2)O6 octahedra, corners with two equivalent Co(1)O6 octahedra, corners with two equivalent Mg(1)O6 pentagonal pyramids, and corners with two equivalent Ge(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-64°. In the second Ge site, Ge(2) is bonded to one O(10), one O(2), one O(3), and one O(7) atom to form GeO4 tetrahedra that share  a cornercorner with one Co(2)O6 octahedra, corners with two equivalent Co(1)O6 octahedra, corners with two equivalent Mg(1)O6 pentagonal pyramids, and corners with two equivalent Ge(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 39-63°. In the third Ge site, Ge(3) is bonded to one O(11), one O(2), one O(3), and one O(6) atom to form GeO4 tetrahedra that share  a cornercorner with one Co(1)O6 octahedra, corners with two equivalent Co(2)O6 octahedra, corners with two equivalent Ge(2)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 31-69°. In the fourth Ge site, Ge(4) is bonded to one O(1), one O(12), one O(4), and one O(5) atom to form distorted GeO4 tetrahedra that share  a cornercorner with one Co(1)O6 octahedra, corners with two equivalent Co(2)O6 octahedra, corners with two equivalent Ge(1)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 35-65°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Ge(1) and one Ge(4) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one Ge(2) and one Ge(3) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Mg(1), one Ge(2), and one Ge(3) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mg(1), one Ge(1), and one Ge(4) atom. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one Co(2), and one Ge(4) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Mg(1), one Co(2), and one Ge(3) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Co(1) and one Ge(2) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Co(1) and one Ge(1) atom. In the ninth O site, O(9) is bonded to one Mg(1), one Co(1), one Co(2), and one Ge(1) atom to form a mixture of distorted corner and edge-sharing OMgCo2Ge tetrahedra. In the tenth O site, O(10) is bonded to one Mg(1), one Co(1), one Co(2), and one Ge(2) atom to form a mixture of distorted corner and edge-sharing OMgCo2Ge tetrahedra. In the eleventh O site, O(11) is bonded in a trigonal non-coplanar geometry to one Co(1), one Co(2), and one Ge(3) atom. In the twelfth O site, O(12) is bonded in a trigonal non-coplanar geometry to one Co(1), one Co(2), and one Ge(4) atom.
MgCo2(GeO3)4 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(10), one O(3), one O(4), one O(5), one O(6), and one O(9) atom to form distorted MgO6 pentagonal pyramids that share corners with two equivalent Ge(1)O4 tetrahedra, corners with two equivalent Ge(2)O4 tetrahedra,  an edgeedge with one Co(1)O6 octahedra, edges with two equivalent Co(2)O6 octahedra,  an edgeedge with one Ge(3)O4 tetrahedra, and  an edgeedge with one Ge(4)O4 tetrahedra. The Mg(1)-O(10) bond length is 2.10 Å. The Mg(1)-O(3) bond length is 2.14 Å. The Mg(1)-O(4) bond length is 2.21 Å. The Mg(1)-O(5) bond length is 2.11 Å. The Mg(1)-O(6) bond length is 2.24 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(7), one O(8), and one O(9) atom to form distorted CoO6 octahedra that share  a cornercorner with one Ge(3)O4 tetrahedra,  a cornercorner with one Ge(4)O4 tetrahedra, corners with two equivalent Ge(1)O4 tetrahedra, corners with two equivalent Ge(2)O4 tetrahedra, edges with two equivalent Co(2)O6 octahedra, and  an edgeedge with one Mg(1)O6 pentagonal pyramid. The Co(1)-O(10) bond length is 2.22 Å. The Co(1)-O(11) bond length is 2.14 Å. The Co(1)-O(12) bond length is 1.96 Å. The Co(1)-O(7) bond length is 1.97 Å. The Co(1)-O(8) bond length is 1.83 Å. The Co(1)-O(9) bond length is 2.23 Å. In the second Co site, Co(2) 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 Ge(1)O4 tetrahedra,  a cornercorner with one Ge(2)O4 tetrahedra, corners with two equivalent Ge(3)O4 tetrahedra, corners with two equivalent Ge(4)O4 tetrahedra, edges with two equivalent Co(1)O6 octahedra, and edges with two equivalent Mg(1)O6 pentagonal pyramids. The Co(2)-O(10) bond length is 2.05 Å. The Co(2)-O(11) bond length is 1.97 Å. The Co(2)-O(12) bond length is 2.07 Å. The Co(2)-O(5) bond length is 1.98 Å. The Co(2)-O(6) bond length is 1.92 Å. The Co(2)-O(9) bond length is 2.08 Å. There are four inequivalent Ge sites. In the first Ge site, Ge(1) is bonded to one O(1), one O(4), one O(8), and one O(9) atom to form GeO4 tetrahedra that share  a cornercorner with one Co(2)O6 octahedra, corners with two equivalent Co(1)O6 octahedra, corners with two equivalent Mg(1)O6 pentagonal pyramids, and corners with two equivalent Ge(4)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-64°. The Ge(1)-O(1) bond length is 1.75 Å. The Ge(1)-O(4) bond length is 1.77 Å. The Ge(1)-O(8) bond length is 1.76 Å. The Ge(1)-O(9) bond length is 1.78 Å. In the second Ge site, Ge(2) is bonded to one O(10), one O(2), one O(3), and one O(7) atom to form GeO4 tetrahedra that share  a cornercorner with one Co(2)O6 octahedra, corners with two equivalent Co(1)O6 octahedra, corners with two equivalent Mg(1)O6 pentagonal pyramids, and corners with two equivalent Ge(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 39-63°. The Ge(2)-O(10) bond length is 1.79 Å. The Ge(2)-O(2) bond length is 1.77 Å. The Ge(2)-O(3) bond length is 1.80 Å. The Ge(2)-O(7) bond length is 1.74 Å. In the third Ge site, Ge(3) is bonded to one O(11), one O(2), one O(3), and one O(6) atom to form GeO4 tetrahedra that share  a cornercorner with one Co(1)O6 octahedra, corners with two equivalent Co(2)O6 octahedra, corners with two equivalent Ge(2)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 31-69°. The Ge(3)-O(11) bond length is 1.77 Å. The Ge(3)-O(2) bond length is 1.77 Å. The Ge(3)-O(3) bond length is 1.83 Å. The Ge(3)-O(6) bond length is 1.76 Å. In the fourth Ge site, Ge(4) is bonded to one O(1), one O(12), one O(4), and one O(5) atom to form distorted GeO4 tetrahedra that share  a cornercorner with one Co(1)O6 octahedra, corners with two equivalent Co(2)O6 octahedra, corners with two equivalent Ge(1)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 pentagonal pyramid. The corner-sharing octahedral tilt angles range from 35-65°. The Ge(4)-O(1) bond length is 1.78 Å. The Ge(4)-O(12) bond length is 1.78 Å. The Ge(4)-O(4) bond length is 1.85 Å. The Ge(4)-O(5) bond length is 1.75 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Ge(1) and one Ge(4) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one Ge(2) and one Ge(3) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Mg(1), one Ge(2), and one Ge(3) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mg(1), one Ge(1), and one Ge(4) atom. In the fifth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one Co(2), and one Ge(4) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Mg(1), one Co(2), and one Ge(3) atom. In the seventh O site, O(7) is bonded in a distorted bent 150 degrees geometry to one Co(1) and one Ge(2) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Co(1) and one Ge(1) atom. In the ninth O site, O(9) is bonded to one Mg(1), one Co(1), one Co(2), and one Ge(1) atom to form a mixture of distorted corner and edge-sharing OMgCo2Ge tetrahedra. In the tenth O site, O(10) is bonded to one Mg(1), one Co(1), one Co(2), and one Ge(2) atom to form a mixture of distorted corner and edge-sharing OMgCo2Ge tetrahedra. In the eleventh O site, O(11) is bonded in a trigonal non-coplanar geometry to one Co(1), one Co(2), and one Ge(3) atom. In the twelfth O site, O(12) is bonded in a trigonal non-coplanar geometry to one Co(1), one Co(2), and one Ge(4) atom.