Ti2O3 crystallizes in the monoclinic P2_1/m space group. There are six inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(2), one O(4), two equivalent O(1), and three equivalent O(3) atoms to form distorted TiO7 pentagonal bipyramids that share  a cornercorner with one Ti(3)O6 octahedra,  a cornercorner with one Ti(4)O6 octahedra, corners with two equivalent Ti(2)O7 pentagonal bipyramids, edges with two equivalent Ti(3)O6 octahedra, edges with two equivalent Ti(2)O7 pentagonal bipyramids, edges with four equivalent Ti(1)O7 pentagonal bipyramids, and  a faceface with one Ti(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 39°. In the second Ti site, Ti(2) is bonded to one O(4), one O(5), two equivalent O(2), and three equivalent O(1) atoms to form distorted TiO7 pentagonal bipyramids that share  a cornercorner with one Ti(5)O6 octahedra, corners with two equivalent Ti(3)O6 octahedra, corners with two equivalent Ti(1)O7 pentagonal bipyramids, edges with two equivalent Ti(4)O6 octahedra, edges with two equivalent Ti(1)O7 pentagonal bipyramids, edges with four equivalent Ti(2)O7 pentagonal bipyramids, and  a faceface with one Ti(1)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 48-57°. In the third Ti site, Ti(3) is bonded to one O(3), one O(8), two equivalent O(4), and two equivalent O(6) atoms to form TiO6 octahedra that share corners with two equivalent Ti(4)O6 octahedra, corners with two equivalent Ti(5)O6 octahedra,  a cornercorner with one Ti(1)O7 pentagonal bipyramid, corners with two equivalent Ti(2)O7 pentagonal bipyramids,  an edgeedge with one Ti(4)O6 octahedra, edges with two equivalent Ti(3)O6 octahedra, and edges with two equivalent Ti(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 15-67°. In the fourth Ti site, Ti(4) is bonded to one O(2), one O(7), two equivalent O(5), and two equivalent O(6) atoms to form TiO6 octahedra that share corners with two equivalent Ti(3)O6 octahedra, corners with two equivalent Ti(5)O6 octahedra,  a cornercorner with one Ti(1)O7 pentagonal bipyramid,  an edgeedge with one Ti(3)O6 octahedra, edges with two equivalent Ti(4)O6 octahedra, and edges with two equivalent Ti(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 15-59°. In the fifth Ti site, Ti(5) is bonded to one O(5), two equivalent O(8), and three equivalent O(9) atoms to form distorted TiO6 octahedra that share corners with two equivalent Ti(3)O6 octahedra, corners with two equivalent Ti(4)O6 octahedra,  a cornercorner with one Ti(2)O7 pentagonal bipyramid, and edges with four equivalent Ti(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 59-67°. In the sixth Ti site, Ti(6) is bonded in a 7-coordinate geometry to one O(6), one O(9), two equivalent O(8), and three equivalent O(7) atoms. There are nine inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ti(1) and three equivalent Ti(2) atoms to form distorted OTi5 trigonal bipyramids that share  a cornercorner with one O(4)Ti4 trigonal pyramid, corners with two equivalent O(2)Ti4 trigonal pyramids, corners with three equivalent O(5)Ti4 trigonal pyramids, corners with four equivalent O(3)Ti4 trigonal pyramids, edges with four equivalent O(1)Ti5 trigonal bipyramids,  an edgeedge with one O(3)Ti4 trigonal pyramid, edges with two equivalent O(4)Ti4 trigonal pyramids, and edges with three equivalent O(2)Ti4 trigonal pyramids. In the second O site, O(2) is bonded to one Ti(1), one Ti(4), and two equivalent Ti(2) atoms to form distorted OTi4 trigonal pyramids that share corners with two equivalent O(6)Ti5 square pyramids,  a cornercorner with one O(7)Ti4 tetrahedra, corners with two equivalent O(1)Ti5 trigonal bipyramids, corners with two equivalent O(2)Ti4 trigonal pyramids, corners with three equivalent O(3)Ti4 trigonal pyramids, corners with three equivalent O(4)Ti4 trigonal pyramids, edges with three equivalent O(1)Ti5 trigonal bipyramids, and edges with two equivalent O(5)Ti4 trigonal pyramids. In the third O site, O(3) is bonded to one Ti(3) and three equivalent Ti(1) atoms to form distorted OTi4 trigonal pyramids that share corners with two equivalent O(6)Ti5 square pyramids,  a cornercorner with one O(8)Ti5 trigonal bipyramid, corners with four equivalent O(1)Ti5 trigonal bipyramids,  a cornercorner with one O(4)Ti4 trigonal pyramid, corners with two equivalent O(3)Ti4 trigonal pyramids, corners with three equivalent O(2)Ti4 trigonal pyramids,  an edgeedge with one O(1)Ti5 trigonal bipyramid, edges with two equivalent O(3)Ti4 trigonal pyramids, and edges with two equivalent O(4)Ti4 trigonal pyramids. In the fourth O site, O(4) is bonded to one Ti(1), one Ti(2), and two equivalent Ti(3) atoms to form distorted OTi4 trigonal pyramids that share corners with two equivalent O(6)Ti5 square pyramids,  a cornercorner with one O(1)Ti5 trigonal bipyramid, corners with two equivalent O(8)Ti5 trigonal bipyramids,  a cornercorner with one O(3)Ti4 trigonal pyramid,  a cornercorner with one O(5)Ti4 trigonal pyramid, corners with two equivalent O(4)Ti4 trigonal pyramids, corners with three equivalent O(2)Ti4 trigonal pyramids,  an edgeedge with one O(6)Ti5 square pyramid, edges with two equivalent O(1)Ti5 trigonal bipyramids, and edges with two equivalent O(3)Ti4 trigonal pyramids. In the fifth O site, O(5) is bonded to one Ti(2), one Ti(5), and two equivalent Ti(4) atoms to form distorted OTi4 trigonal pyramids that share corners with two equivalent O(6)Ti5 square pyramids, corners with two equivalent O(7)Ti4 tetrahedra, corners with two equivalent O(8)Ti5 trigonal bipyramids, corners with three equivalent O(1)Ti5 trigonal bipyramids,  a cornercorner with one O(4)Ti4 trigonal pyramid, corners with two equivalent O(5)Ti4 trigonal pyramids, corners with three equivalent O(9)Ti4 trigonal pyramids,  an edgeedge with one O(6)Ti5 square pyramid, and edges with two equivalent O(2)Ti4 trigonal pyramids. In the sixth O site, O(6) is bonded to one Ti(6), two equivalent Ti(3), and two equivalent Ti(4) atoms to form OTi5 square pyramids that share  a cornercorner with one O(7)Ti4 tetrahedra,  a cornercorner with one O(9)Ti4 trigonal pyramid, corners with two equivalent O(2)Ti4 trigonal pyramids, corners with two equivalent O(3)Ti4 trigonal pyramids, corners with two equivalent O(4)Ti4 trigonal pyramids, corners with two equivalent O(5)Ti4 trigonal pyramids, edges with two equivalent O(6)Ti5 square pyramids, edges with two equivalent O(7)Ti4 tetrahedra, edges with two equivalent O(8)Ti5 trigonal bipyramids,  an edgeedge with one O(4)Ti4 trigonal pyramid, and  an edgeedge with one O(5)Ti4 trigonal pyramid. In the seventh O site, O(7) is bonded to one Ti(4) and three equivalent Ti(6) atoms to form distorted OTi4 tetrahedra that share  a cornercorner with one O(6)Ti5 square pyramid, corners with two equivalent O(7)Ti4 tetrahedra, corners with four equivalent O(8)Ti5 trigonal bipyramids,  a cornercorner with one O(2)Ti4 trigonal pyramid, corners with two equivalent O(5)Ti4 trigonal pyramids, corners with three equivalent O(9)Ti4 trigonal pyramids, edges with two equivalent O(6)Ti5 square pyramids, edges with two equivalent O(7)Ti4 tetrahedra, and  an edgeedge with one O(8)Ti5 trigonal bipyramid. In the eighth O site, O(8) is bonded to one Ti(3), two equivalent Ti(5), and two equivalent Ti(6) atoms to form distorted OTi5 trigonal bipyramids that share corners with four equivalent O(7)Ti4 tetrahedra,  a cornercorner with one O(3)Ti4 trigonal pyramid, corners with two equivalent O(4)Ti4 trigonal pyramids, corners with two equivalent O(5)Ti4 trigonal pyramids, corners with two equivalent O(9)Ti4 trigonal pyramids, edges with two equivalent O(6)Ti5 square pyramids,  an edgeedge with one O(7)Ti4 tetrahedra, edges with two equivalent O(8)Ti5 trigonal bipyramids, and edges with three equivalent O(9)Ti4 trigonal pyramids. In the ninth O site, O(9) is bonded to one Ti(6) and three equivalent Ti(5) atoms to form OTi4 trigonal pyramids that share  a cornercorner with one O(6)Ti5 square pyramid, corners with three equivalent O(7)Ti4 tetrahedra, corners with two equivalent O(8)Ti5 trigonal bipyramids, corners with two equivalent O(9)Ti4 trigonal pyramids, corners with three equivalent O(5)Ti4 trigonal pyramids, edges with three equivalent O(8)Ti5 trigonal bipyramids, and edges with two equivalent O(9)Ti4 trigonal pyramids.
Ti2O3 crystallizes in the monoclinic P2_1/m space group. There are six inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(2), one O(4), two equivalent O(1), and three equivalent O(3) atoms to form distorted TiO7 pentagonal bipyramids that share  a cornercorner with one Ti(3)O6 octahedra,  a cornercorner with one Ti(4)O6 octahedra, corners with two equivalent Ti(2)O7 pentagonal bipyramids, edges with two equivalent Ti(3)O6 octahedra, edges with two equivalent Ti(2)O7 pentagonal bipyramids, edges with four equivalent Ti(1)O7 pentagonal bipyramids, and  a faceface with one Ti(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 39°. The Ti(1)-O(2) bond length is 2.09 Å. The Ti(1)-O(4) bond length is 2.21 Å. Both Ti(1)-O(1) bond lengths are 2.10 Å. There is one shorter (2.06 Å) and two longer (2.07 Å) Ti(1)-O(3) bond lengths. In the second Ti site, Ti(2) is bonded to one O(4), one O(5), two equivalent O(2), and three equivalent O(1) atoms to form distorted TiO7 pentagonal bipyramids that share  a cornercorner with one Ti(5)O6 octahedra, corners with two equivalent Ti(3)O6 octahedra, corners with two equivalent Ti(1)O7 pentagonal bipyramids, edges with two equivalent Ti(4)O6 octahedra, edges with two equivalent Ti(1)O7 pentagonal bipyramids, edges with four equivalent Ti(2)O7 pentagonal bipyramids, and  a faceface with one Ti(1)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles range from 48-57°. The Ti(2)-O(4) bond length is 2.07 Å. The Ti(2)-O(5) bond length is 2.22 Å. Both Ti(2)-O(2) bond lengths are 2.06 Å. There are two shorter (2.13 Å) and one longer (2.15 Å) Ti(2)-O(1) bond length. In the third Ti site, Ti(3) is bonded to one O(3), one O(8), two equivalent O(4), and two equivalent O(6) atoms to form TiO6 octahedra that share corners with two equivalent Ti(4)O6 octahedra, corners with two equivalent Ti(5)O6 octahedra,  a cornercorner with one Ti(1)O7 pentagonal bipyramid, corners with two equivalent Ti(2)O7 pentagonal bipyramids,  an edgeedge with one Ti(4)O6 octahedra, edges with two equivalent Ti(3)O6 octahedra, and edges with two equivalent Ti(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 15-67°. The Ti(3)-O(3) bond length is 1.94 Å. The Ti(3)-O(8) bond length is 2.04 Å. Both Ti(3)-O(4) bond lengths are 2.02 Å. Both Ti(3)-O(6) bond lengths are 2.04 Å. In the fourth Ti site, Ti(4) is bonded to one O(2), one O(7), two equivalent O(5), and two equivalent O(6) atoms to form TiO6 octahedra that share corners with two equivalent Ti(3)O6 octahedra, corners with two equivalent Ti(5)O6 octahedra,  a cornercorner with one Ti(1)O7 pentagonal bipyramid,  an edgeedge with one Ti(3)O6 octahedra, edges with two equivalent Ti(4)O6 octahedra, and edges with two equivalent Ti(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 15-59°. The Ti(4)-O(2) bond length is 2.00 Å. The Ti(4)-O(7) bond length is 2.01 Å. Both Ti(4)-O(5) bond lengths are 2.05 Å. Both Ti(4)-O(6) bond lengths are 2.07 Å. In the fifth Ti site, Ti(5) is bonded to one O(5), two equivalent O(8), and three equivalent O(9) atoms to form distorted TiO6 octahedra that share corners with two equivalent Ti(3)O6 octahedra, corners with two equivalent Ti(4)O6 octahedra,  a cornercorner with one Ti(2)O7 pentagonal bipyramid, and edges with four equivalent Ti(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 59-67°. The Ti(5)-O(5) bond length is 2.03 Å. Both Ti(5)-O(8) bond lengths are 2.16 Å. There are two shorter (2.01 Å) and one longer (2.11 Å) Ti(5)-O(9) bond length. In the sixth Ti site, Ti(6) is bonded in a 7-coordinate geometry to one O(6), one O(9), two equivalent O(8), and three equivalent O(7) atoms. The Ti(6)-O(6) bond length is 2.32 Å. The Ti(6)-O(9) bond length is 2.03 Å. Both Ti(6)-O(8) bond lengths are 2.19 Å. All Ti(6)-O(7) bond lengths are 2.06 Å. There are nine inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ti(1) and three equivalent Ti(2) atoms to form distorted OTi5 trigonal bipyramids that share  a cornercorner with one O(4)Ti4 trigonal pyramid, corners with two equivalent O(2)Ti4 trigonal pyramids, corners with three equivalent O(5)Ti4 trigonal pyramids, corners with four equivalent O(3)Ti4 trigonal pyramids, edges with four equivalent O(1)Ti5 trigonal bipyramids,  an edgeedge with one O(3)Ti4 trigonal pyramid, edges with two equivalent O(4)Ti4 trigonal pyramids, and edges with three equivalent O(2)Ti4 trigonal pyramids. In the second O site, O(2) is bonded to one Ti(1), one Ti(4), and two equivalent Ti(2) atoms to form distorted OTi4 trigonal pyramids that share corners with two equivalent O(6)Ti5 square pyramids,  a cornercorner with one O(7)Ti4 tetrahedra, corners with two equivalent O(1)Ti5 trigonal bipyramids, corners with two equivalent O(2)Ti4 trigonal pyramids, corners with three equivalent O(3)Ti4 trigonal pyramids, corners with three equivalent O(4)Ti4 trigonal pyramids, edges with three equivalent O(1)Ti5 trigonal bipyramids, and edges with two equivalent O(5)Ti4 trigonal pyramids. In the third O site, O(3) is bonded to one Ti(3) and three equivalent Ti(1) atoms to form distorted OTi4 trigonal pyramids that share corners with two equivalent O(6)Ti5 square pyramids,  a cornercorner with one O(8)Ti5 trigonal bipyramid, corners with four equivalent O(1)Ti5 trigonal bipyramids,  a cornercorner with one O(4)Ti4 trigonal pyramid, corners with two equivalent O(3)Ti4 trigonal pyramids, corners with three equivalent O(2)Ti4 trigonal pyramids,  an edgeedge with one O(1)Ti5 trigonal bipyramid, edges with two equivalent O(3)Ti4 trigonal pyramids, and edges with two equivalent O(4)Ti4 trigonal pyramids. In the fourth O site, O(4) is bonded to one Ti(1), one Ti(2), and two equivalent Ti(3) atoms to form distorted OTi4 trigonal pyramids that share corners with two equivalent O(6)Ti5 square pyramids,  a cornercorner with one O(1)Ti5 trigonal bipyramid, corners with two equivalent O(8)Ti5 trigonal bipyramids,  a cornercorner with one O(3)Ti4 trigonal pyramid,  a cornercorner with one O(5)Ti4 trigonal pyramid, corners with two equivalent O(4)Ti4 trigonal pyramids, corners with three equivalent O(2)Ti4 trigonal pyramids,  an edgeedge with one O(6)Ti5 square pyramid, edges with two equivalent O(1)Ti5 trigonal bipyramids, and edges with two equivalent O(3)Ti4 trigonal pyramids. In the fifth O site, O(5) is bonded to one Ti(2), one Ti(5), and two equivalent Ti(4) atoms to form distorted OTi4 trigonal pyramids that share corners with two equivalent O(6)Ti5 square pyramids, corners with two equivalent O(7)Ti4 tetrahedra, corners with two equivalent O(8)Ti5 trigonal bipyramids, corners with three equivalent O(1)Ti5 trigonal bipyramids,  a cornercorner with one O(4)Ti4 trigonal pyramid, corners with two equivalent O(5)Ti4 trigonal pyramids, corners with three equivalent O(9)Ti4 trigonal pyramids,  an edgeedge with one O(6)Ti5 square pyramid, and edges with two equivalent O(2)Ti4 trigonal pyramids. In the sixth O site, O(6) is bonded to one Ti(6), two equivalent Ti(3), and two equivalent Ti(4) atoms to form OTi5 square pyramids that share  a cornercorner with one O(7)Ti4 tetrahedra,  a cornercorner with one O(9)Ti4 trigonal pyramid, corners with two equivalent O(2)Ti4 trigonal pyramids, corners with two equivalent O(3)Ti4 trigonal pyramids, corners with two equivalent O(4)Ti4 trigonal pyramids, corners with two equivalent O(5)Ti4 trigonal pyramids, edges with two equivalent O(6)Ti5 square pyramids, edges with two equivalent O(7)Ti4 tetrahedra, edges with two equivalent O(8)Ti5 trigonal bipyramids,  an edgeedge with one O(4)Ti4 trigonal pyramid, and  an edgeedge with one O(5)Ti4 trigonal pyramid. In the seventh O site, O(7) is bonded to one Ti(4) and three equivalent Ti(6) atoms to form distorted OTi4 tetrahedra that share  a cornercorner with one O(6)Ti5 square pyramid, corners with two equivalent O(7)Ti4 tetrahedra, corners with four equivalent O(8)Ti5 trigonal bipyramids,  a cornercorner with one O(2)Ti4 trigonal pyramid, corners with two equivalent O(5)Ti4 trigonal pyramids, corners with three equivalent O(9)Ti4 trigonal pyramids, edges with two equivalent O(6)Ti5 square pyramids, edges with two equivalent O(7)Ti4 tetrahedra, and  an edgeedge with one O(8)Ti5 trigonal bipyramid. In the eighth O site, O(8) is bonded to one Ti(3), two equivalent Ti(5), and two equivalent Ti(6) atoms to form distorted OTi5 trigonal bipyramids that share corners with four equivalent O(7)Ti4 tetrahedra,  a cornercorner with one O(3)Ti4 trigonal pyramid, corners with two equivalent O(4)Ti4 trigonal pyramids, corners with two equivalent O(5)Ti4 trigonal pyramids, corners with two equivalent O(9)Ti4 trigonal pyramids, edges with two equivalent O(6)Ti5 square pyramids,  an edgeedge with one O(7)Ti4 tetrahedra, edges with two equivalent O(8)Ti5 trigonal bipyramids, and edges with three equivalent O(9)Ti4 trigonal pyramids. In the ninth O site, O(9) is bonded to one Ti(6) and three equivalent Ti(5) atoms to form OTi4 trigonal pyramids that share  a cornercorner with one O(6)Ti5 square pyramid, corners with three equivalent O(7)Ti4 tetrahedra, corners with two equivalent O(8)Ti5 trigonal bipyramids, corners with two equivalent O(9)Ti4 trigonal pyramids, corners with three equivalent O(5)Ti4 trigonal pyramids, edges with three equivalent O(8)Ti5 trigonal bipyramids, and edges with two equivalent O(9)Ti4 trigonal pyramids.