Mg14BCO16 crystallizes in the orthorhombic Pmmm space group. There are nine inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(6), and two equivalent O(9) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedra are not tilted. In the second Mg site, Mg(2) is bonded to two equivalent O(2), two equivalent O(7), and two equivalent O(9) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedra are not tilted. In the third Mg site, Mg(3) is bonded to one O(4), one O(5), two equivalent O(3), and two equivalent O(8) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-33°. In the fourth Mg site, Mg(4) is bonded to one O(6), one O(7), two equivalent O(3), and two equivalent O(9) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the fifth Mg site, Mg(4) is bonded to one O(6), one O(7), two equivalent O(3), and two equivalent O(9) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the sixth Mg site, Mg(5) is bonded to one O(4), one O(6), two equivalent O(1), and two equivalent O(3) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-7°. In the seventh Mg site, Mg(6) is bonded to one O(5), one O(7), two equivalent O(2), and two equivalent O(3) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the eighth Mg site, Mg(6) is bonded to one O(5), one O(7), two equivalent O(2), and two equivalent O(3) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. In the ninth Mg site, Mg(7) is bonded to one O(1), one O(2), one O(8), one O(9), and two equivalent O(3) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-35°. B(1) is bonded in a distorted linear geometry to two equivalent O(4) and two equivalent O(8) atoms. C(1) is bonded in a distorted square co-planar geometry to two equivalent O(2) and two equivalent O(5) atoms. There are nine inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), two equivalent Mg(5), and two equivalent Mg(7) atoms to form distorted OMg5 square pyramids that share corners with two equivalent O(4)Mg4B2 octahedra, corners with two equivalent O(2)Mg5C square pyramids, corners with three equivalent O(1)Mg5 square pyramids, edges with two equivalent O(6)Mg6 octahedra, edges with two equivalent O(9)Mg6 octahedra, and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles are 87°. In the second O site, O(2) is bonded to one Mg(2), two equivalent Mg(6), two equivalent Mg(7), and one C(1) atom to form distorted OMg5C square pyramids that share corners with two equivalent O(1)Mg5 square pyramids, corners with four equivalent O(2)Mg5C square pyramids, edges with two equivalent O(5)Mg4C2 octahedra, edges with two equivalent O(7)Mg6 octahedra, edges with two equivalent O(9)Mg6 octahedra, and edges with four equivalent O(3)Mg6 octahedra. In the third O site, O(3) is bonded to one Mg(3), one Mg(4), one Mg(5), one Mg(6), and two equivalent Mg(7) atoms to form OMg6 octahedra that share corners with six equivalent O(3)Mg6 octahedra,  an edgeedge with one O(4)Mg4B2 octahedra,  an edgeedge with one O(5)Mg4C2 octahedra,  an edgeedge with one O(6)Mg6 octahedra,  an edgeedge with one O(7)Mg6 octahedra, edges with two equivalent O(9)Mg6 octahedra, edges with two equivalent O(1)Mg5 square pyramids, and edges with two equivalent O(2)Mg5C square pyramids. The corner-sharing octahedral tilt angles range from 0-4°. In the fourth O site, O(4) is bonded to two equivalent Mg(3), two equivalent Mg(5), and two equivalent B(1) atoms to form OMg4B2 octahedra that share corners with two equivalent O(4)Mg4B2 octahedra, corners with two equivalent O(5)Mg4C2 octahedra, corners with two equivalent O(6)Mg6 octahedra, corners with four equivalent O(1)Mg5 square pyramids, and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedra are not tilted. In the fifth O site, O(5) is bonded to two equivalent Mg(3); two Mg(6,6); and two equivalent C(1) atoms to form distorted OMg4C2 octahedra that share corners with two equivalent O(4)Mg4B2 octahedra, corners with two equivalent O(5)Mg4C2 octahedra, corners with two equivalent O(7)Mg6 octahedra, edges with four equivalent O(3)Mg6 octahedra, and edges with four equivalent O(2)Mg5C square pyramids. The corner-sharing octahedra are not tilted. In the sixth O site, O(6) is bonded to two equivalent Mg(1); two Mg(4,4); and two equivalent Mg(5) atoms to form OMg6 octahedra that share corners with two equivalent O(4)Mg4B2 octahedra, corners with two equivalent O(6)Mg6 octahedra, corners with two equivalent O(7)Mg6 octahedra, edges with four equivalent O(3)Mg6 octahedra, edges with four equivalent O(9)Mg6 octahedra, and edges with four equivalent O(1)Mg5 square pyramids. The corner-sharing octahedra are not tilted. In the seventh O site, O(7) is bonded to two equivalent Mg(2); two Mg(4,4); and two Mg(6,6) atoms to form OMg6 octahedra that share corners with two equivalent O(5)Mg4C2 octahedra, corners with two equivalent O(6)Mg6 octahedra, corners with two equivalent O(7)Mg6 octahedra, edges with four equivalent O(3)Mg6 octahedra, edges with four equivalent O(9)Mg6 octahedra, and edges with four equivalent O(2)Mg5C square pyramids. The corner-sharing octahedra are not tilted. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to two equivalent Mg(3), two equivalent Mg(7), and one B(1) atom. In the ninth O site, O(9) is bonded to one Mg(1), one Mg(2), two equivalent Mg(4), and two equivalent Mg(7) atoms to form OMg6 octahedra that share corners with four equivalent O(9)Mg6 octahedra, edges with two equivalent O(6)Mg6 octahedra, edges with two equivalent O(7)Mg6 octahedra, edges with four equivalent O(3)Mg6 octahedra, edges with two equivalent O(1)Mg5 square pyramids, and edges with two equivalent O(2)Mg5C square pyramids. The corner-sharing octahedral tilt angles range from 0-1°.
Mg14BCO16 crystallizes in the orthorhombic Pmmm space group. There are nine inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(6), and two equivalent O(9) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedra are not tilted. Both Mg(1)-O(1) bond lengths are 2.04 Å. Both Mg(1)-O(6) bond lengths are 2.12 Å. Both Mg(1)-O(9) bond lengths are 2.12 Å. In the second Mg site, Mg(2) is bonded to two equivalent O(2), two equivalent O(7), and two equivalent O(9) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedra are not tilted. Both Mg(2)-O(2) bond lengths are 2.15 Å. Both Mg(2)-O(7) bond lengths are 2.12 Å. Both Mg(2)-O(9) bond lengths are 2.07 Å. In the third Mg site, Mg(3) is bonded to one O(4), one O(5), two equivalent O(3), and two equivalent O(8) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-33°. The Mg(3)-O(4) bond length is 2.03 Å. The Mg(3)-O(5) bond length is 2.17 Å. Both Mg(3)-O(3) bond lengths are 2.09 Å. Both Mg(3)-O(8) bond lengths are 2.22 Å. In the fourth Mg site, Mg(4) is bonded to one O(6), one O(7), two equivalent O(3), and two equivalent O(9) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. The Mg(4)-O(6) bond length is 2.10 Å. The Mg(4)-O(7) bond length is 2.10 Å. Both Mg(4)-O(3) bond lengths are 2.20 Å. Both Mg(4)-O(9) bond lengths are 2.12 Å. In the fifth Mg site, Mg(4) is bonded to one O(6), one O(7), two equivalent O(3), and two equivalent O(9) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. The Mg(4)-O(6) bond length is 2.10 Å. The Mg(4)-O(7) bond length is 2.10 Å. Both Mg(4)-O(3) bond lengths are 2.20 Å. Both Mg(4)-O(9) bond lengths are 2.12 Å. In the sixth Mg site, Mg(5) is bonded to one O(4), one O(6), two equivalent O(1), and two equivalent O(3) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-7°. The Mg(5)-O(4) bond length is 2.12 Å. The Mg(5)-O(6) bond length is 2.17 Å. Both Mg(5)-O(1) bond lengths are 2.13 Å. Both Mg(5)-O(3) bond lengths are 2.11 Å. In the seventh Mg site, Mg(6) is bonded to one O(5), one O(7), two equivalent O(2), and two equivalent O(3) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. The Mg(6)-O(5) bond length is 2.09 Å. The Mg(6)-O(7) bond length is 2.20 Å. Both Mg(6)-O(2) bond lengths are 2.12 Å. Both Mg(6)-O(3) bond lengths are 2.09 Å. In the eighth Mg site, Mg(6) is bonded to one O(5), one O(7), two equivalent O(2), and two equivalent O(3) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-2°. The Mg(6)-O(5) bond length is 2.09 Å. The Mg(6)-O(7) bond length is 2.20 Å. Both Mg(6)-O(2) bond lengths are 2.12 Å. Both Mg(6)-O(3) bond lengths are 2.09 Å. In the ninth Mg site, Mg(7) is bonded to one O(1), one O(2), one O(8), one O(9), and two equivalent O(3) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 0-35°. The Mg(7)-O(1) bond length is 2.07 Å. The Mg(7)-O(2) bond length is 2.13 Å. The Mg(7)-O(8) bond length is 2.24 Å. The Mg(7)-O(9) bond length is 2.15 Å. Both Mg(7)-O(3) bond lengths are 2.12 Å. B(1) is bonded in a distorted linear geometry to two equivalent O(4) and two equivalent O(8) atoms. Both B(1)-O(4) bond lengths are 2.12 Å. Both B(1)-O(8) bond lengths are 1.39 Å. C(1) is bonded in a distorted square co-planar geometry to two equivalent O(2) and two equivalent O(5) atoms. Both C(1)-O(2) bond lengths are 2.14 Å. Both C(1)-O(5) bond lengths are 2.12 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded to one Mg(1), two equivalent Mg(5), and two equivalent Mg(7) atoms to form distorted OMg5 square pyramids that share corners with two equivalent O(4)Mg4B2 octahedra, corners with two equivalent O(2)Mg5C square pyramids, corners with three equivalent O(1)Mg5 square pyramids, edges with two equivalent O(6)Mg6 octahedra, edges with two equivalent O(9)Mg6 octahedra, and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedral tilt angles are 87°. In the second O site, O(2) is bonded to one Mg(2), two equivalent Mg(6), two equivalent Mg(7), and one C(1) atom to form distorted OMg5C square pyramids that share corners with two equivalent O(1)Mg5 square pyramids, corners with four equivalent O(2)Mg5C square pyramids, edges with two equivalent O(5)Mg4C2 octahedra, edges with two equivalent O(7)Mg6 octahedra, edges with two equivalent O(9)Mg6 octahedra, and edges with four equivalent O(3)Mg6 octahedra. In the third O site, O(3) is bonded to one Mg(3), one Mg(4), one Mg(5), one Mg(6), and two equivalent Mg(7) atoms to form OMg6 octahedra that share corners with six equivalent O(3)Mg6 octahedra,  an edgeedge with one O(4)Mg4B2 octahedra,  an edgeedge with one O(5)Mg4C2 octahedra,  an edgeedge with one O(6)Mg6 octahedra,  an edgeedge with one O(7)Mg6 octahedra, edges with two equivalent O(9)Mg6 octahedra, edges with two equivalent O(1)Mg5 square pyramids, and edges with two equivalent O(2)Mg5C square pyramids. The corner-sharing octahedral tilt angles range from 0-4°. In the fourth O site, O(4) is bonded to two equivalent Mg(3), two equivalent Mg(5), and two equivalent B(1) atoms to form OMg4B2 octahedra that share corners with two equivalent O(4)Mg4B2 octahedra, corners with two equivalent O(5)Mg4C2 octahedra, corners with two equivalent O(6)Mg6 octahedra, corners with four equivalent O(1)Mg5 square pyramids, and edges with four equivalent O(3)Mg6 octahedra. The corner-sharing octahedra are not tilted. In the fifth O site, O(5) is bonded to two equivalent Mg(3); two Mg(6,6); and two equivalent C(1) atoms to form distorted OMg4C2 octahedra that share corners with two equivalent O(4)Mg4B2 octahedra, corners with two equivalent O(5)Mg4C2 octahedra, corners with two equivalent O(7)Mg6 octahedra, edges with four equivalent O(3)Mg6 octahedra, and edges with four equivalent O(2)Mg5C square pyramids. The corner-sharing octahedra are not tilted. In the sixth O site, O(6) is bonded to two equivalent Mg(1); two Mg(4,4); and two equivalent Mg(5) atoms to form OMg6 octahedra that share corners with two equivalent O(4)Mg4B2 octahedra, corners with two equivalent O(6)Mg6 octahedra, corners with two equivalent O(7)Mg6 octahedra, edges with four equivalent O(3)Mg6 octahedra, edges with four equivalent O(9)Mg6 octahedra, and edges with four equivalent O(1)Mg5 square pyramids. The corner-sharing octahedra are not tilted. In the seventh O site, O(7) is bonded to two equivalent Mg(2); two Mg(4,4); and two Mg(6,6) atoms to form OMg6 octahedra that share corners with two equivalent O(5)Mg4C2 octahedra, corners with two equivalent O(6)Mg6 octahedra, corners with two equivalent O(7)Mg6 octahedra, edges with four equivalent O(3)Mg6 octahedra, edges with four equivalent O(9)Mg6 octahedra, and edges with four equivalent O(2)Mg5C square pyramids. The corner-sharing octahedra are not tilted. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to two equivalent Mg(3), two equivalent Mg(7), and one B(1) atom. In the ninth O site, O(9) is bonded to one Mg(1), one Mg(2), two equivalent Mg(4), and two equivalent Mg(7) atoms to form OMg6 octahedra that share corners with four equivalent O(9)Mg6 octahedra, edges with two equivalent O(6)Mg6 octahedra, edges with two equivalent O(7)Mg6 octahedra, edges with four equivalent O(3)Mg6 octahedra, edges with two equivalent O(1)Mg5 square pyramids, and edges with two equivalent O(2)Mg5C square pyramids. The corner-sharing octahedral tilt angles range from 0-1°.