MgTm(FeO2)2 is Corundum-derived structured and crystallizes in the trigonal R-3m space group. Mg(1) is bonded to six equivalent O(1) atoms to form MgO6 octahedra that share corners with six equivalent Fe(1)O4 trigonal pyramids, edges with six equivalent Mg(1)O6 octahedra, and edges with six equivalent Fe(1)O4 trigonal pyramids. Tm(1) is bonded to six equivalent O(2) atoms to form TmO6 octahedra that share corners with six equivalent Fe(1)O4 trigonal pyramids and edges with six equivalent Tm(1)O6 octahedra. Fe(1) is bonded to one O(2) and three equivalent O(1) atoms to form distorted FeO4 trigonal pyramids that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Tm(1)O6 octahedra, corners with six equivalent Fe(1)O4 trigonal pyramids, and edges with three equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-59°. There are two inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Mg(1) and three equivalent Fe(1) atoms to form OMg3Fe3 octahedra that share corners with three equivalent O(1)Mg3Fe3 octahedra, corners with three equivalent O(2)Tm3Fe trigonal pyramids, and edges with nine equivalent O(1)Mg3Fe3 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded to three equivalent Tm(1) and one Fe(1) atom to form distorted OTm3Fe trigonal pyramids that share corners with three equivalent O(1)Mg3Fe3 octahedra, corners with nine equivalent O(2)Tm3Fe trigonal pyramids, and edges with three equivalent O(2)Tm3Fe trigonal pyramids. The corner-sharing octahedral tilt angles are 59°.
MgTm(FeO2)2 is Corundum-derived structured and crystallizes in the trigonal R-3m space group. Mg(1) is bonded to six equivalent O(1) atoms to form MgO6 octahedra that share corners with six equivalent Fe(1)O4 trigonal pyramids, edges with six equivalent Mg(1)O6 octahedra, and edges with six equivalent Fe(1)O4 trigonal pyramids. All Mg(1)-O(1) bond lengths are 2.21 Å. Tm(1) is bonded to six equivalent O(2) atoms to form TmO6 octahedra that share corners with six equivalent Fe(1)O4 trigonal pyramids and edges with six equivalent Tm(1)O6 octahedra. All Tm(1)-O(2) bond lengths are 2.21 Å. Fe(1) is bonded to one O(2) and three equivalent O(1) atoms to form distorted FeO4 trigonal pyramids that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Tm(1)O6 octahedra, corners with six equivalent Fe(1)O4 trigonal pyramids, and edges with three equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-59°. The Fe(1)-O(2) bond length is 2.00 Å. All Fe(1)-O(1) bond lengths are 2.21 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Mg(1) and three equivalent Fe(1) atoms to form OMg3Fe3 octahedra that share corners with three equivalent O(1)Mg3Fe3 octahedra, corners with three equivalent O(2)Tm3Fe trigonal pyramids, and edges with nine equivalent O(1)Mg3Fe3 octahedra. The corner-sharing octahedra are not tilted. In the second O site, O(2) is bonded to three equivalent Tm(1) and one Fe(1) atom to form distorted OTm3Fe trigonal pyramids that share corners with three equivalent O(1)Mg3Fe3 octahedra, corners with nine equivalent O(2)Tm3Fe trigonal pyramids, and edges with three equivalent O(2)Tm3Fe trigonal pyramids. The corner-sharing octahedral tilt angles are 59°.