MgTm6WO12 is Corundum-derived structured and crystallizes in the trigonal R-3 space group. Mg(1) is bonded to six equivalent O(2) atoms to form MgO6 octahedra that share corners with six equivalent Tm(1)O6 pentagonal pyramids and edges with six equivalent Tm(1)O6 pentagonal pyramids. Tm(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted TmO6 pentagonal pyramids that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one W(1)O6 octahedra, corners with four equivalent Tm(1)O6 pentagonal pyramids,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one W(1)O6 octahedra, and edges with four equivalent Tm(1)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 34-48°. W(1) is bonded to six equivalent O(1) atoms to form WO6 octahedra that share corners with six equivalent Tm(1)O6 pentagonal pyramids and edges with six equivalent Tm(1)O6 pentagonal pyramids. There are two inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Tm(1) and one W(1) atom to form a mixture of distorted edge and corner-sharing OTm3W trigonal pyramids. In the second O site, O(2) is bonded in a see-saw-like geometry to one Mg(1) and three equivalent Tm(1) atoms.
MgTm6WO12 is Corundum-derived structured and crystallizes in the trigonal R-3 space group. Mg(1) is bonded to six equivalent O(2) atoms to form MgO6 octahedra that share corners with six equivalent Tm(1)O6 pentagonal pyramids and edges with six equivalent Tm(1)O6 pentagonal pyramids. All Mg(1)-O(2) bond lengths are 2.10 Å. Tm(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted TmO6 pentagonal pyramids that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one W(1)O6 octahedra, corners with four equivalent Tm(1)O6 pentagonal pyramids,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one W(1)O6 octahedra, and edges with four equivalent Tm(1)O6 pentagonal pyramids. The corner-sharing octahedral tilt angles range from 34-48°. There are a spread of Tm(1)-O(1) bond distances ranging from 2.21-2.37 Å. There are two shorter (2.21 Å) and one longer (2.22 Å) Tm(1)-O(2) bond length. W(1) is bonded to six equivalent O(1) atoms to form WO6 octahedra that share corners with six equivalent Tm(1)O6 pentagonal pyramids and edges with six equivalent Tm(1)O6 pentagonal pyramids. All W(1)-O(1) bond lengths are 2.10 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Tm(1) and one W(1) atom to form a mixture of distorted edge and corner-sharing OTm3W trigonal pyramids. In the second O site, O(2) is bonded in a see-saw-like geometry to one Mg(1) and three equivalent Tm(1) atoms.