Mg2Ta2Mn2O9 is Ilmenite-derived structured and crystallizes in the trigonal P-3c1 space group. Mg(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted MgO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Ta(1)O6 octahedra, corners with three equivalent Mn(1)O6 octahedra, edges with three equivalent Ta(1)O6 octahedra, and  a faceface with one Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-66°. Ta(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted TaO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with six equivalent Mn(1)O6 octahedra, edges with three equivalent Mg(1)O6 octahedra, and  a faceface with one Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-59°. Mn(1) is bonded to six equivalent O(2) atoms to form MnO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with six equivalent Ta(1)O6 octahedra, edges with three equivalent Mn(1)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-59°. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1) and two equivalent Ta(1) atoms to form a mixture of distorted corner and edge-sharing OMg2Ta2 trigonal pyramids. In the second O site, O(2) is bonded in a distorted see-saw-like geometry to one Mg(1), one Ta(1), and two equivalent Mn(1) atoms.
Mg2Ta2Mn2O9 is Ilmenite-derived structured and crystallizes in the trigonal P-3c1 space group. Mg(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted MgO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Ta(1)O6 octahedra, corners with three equivalent Mn(1)O6 octahedra, edges with three equivalent Ta(1)O6 octahedra, and  a faceface with one Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-66°. All Mg(1)-O(1) bond lengths are 2.08 Å. All Mg(1)-O(2) bond lengths are 2.23 Å. Ta(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form distorted TaO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with six equivalent Mn(1)O6 octahedra, edges with three equivalent Mg(1)O6 octahedra, and  a faceface with one Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-59°. All Ta(1)-O(1) bond lengths are 2.14 Å. All Ta(1)-O(2) bond lengths are 1.92 Å. Mn(1) is bonded to six equivalent O(2) atoms to form MnO6 octahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with six equivalent Ta(1)O6 octahedra, edges with three equivalent Mn(1)O6 octahedra, and  a faceface with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 45-59°. There are three shorter (2.16 Å) and three longer (2.27 Å) Mn(1)-O(2) bond lengths. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1) and two equivalent Ta(1) atoms to form a mixture of distorted corner and edge-sharing OMg2Ta2 trigonal pyramids. In the second O site, O(2) is bonded in a distorted see-saw-like geometry to one Mg(1), one Ta(1), and two equivalent Mn(1) atoms.