Mg3B2O6 crystallizes in the orthorhombic Pnnm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 57-66°. In the second Mg site, Mg(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 66°. B(1) is bonded in a trigonal planar geometry to one O(2) and two equivalent O(1) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Mg(2), two equivalent Mg(1), and one B(1) atom to form a mixture of distorted edge and corner-sharing OMg3B trigonal pyramids. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(2), two equivalent Mg(1), and one B(1) atom.
Mg3B2O6 crystallizes in the orthorhombic Pnnm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles range from 57-66°. Both Mg(1)-O(2) bond lengths are 2.16 Å. There are two shorter (2.04 Å) and two longer (2.12 Å) Mg(1)-O(1) bond lengths. In the second Mg site, Mg(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 66°. Both Mg(2)-O(2) bond lengths are 2.07 Å. All Mg(2)-O(1) bond lengths are 2.09 Å. B(1) is bonded in a trigonal planar geometry to one O(2) and two equivalent O(1) atoms. The B(1)-O(2) bond length is 1.38 Å. Both B(1)-O(1) bond lengths are 1.39 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Mg(2), two equivalent Mg(1), and one B(1) atom to form a mixture of distorted edge and corner-sharing OMg3B trigonal pyramids. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(2), two equivalent Mg(1), and one B(1) atom.