Ti8O15 crystallizes in the triclinic P-1 space group. There are eight inequivalent Ti sites. In the first Ti site, Ti(1) is bonded in a 6-coordinate geometry to one O(10), one O(14), one O(4), one O(9), and two equivalent O(12) atoms. In the second Ti site, Ti(2) is bonded to one O(12), one O(3), one O(4), one O(9), and two equivalent O(10) atoms to form a mixture of distorted edge and corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 44-52°. In the third Ti site, Ti(3) is bonded to one O(14), one O(2), one O(5), one O(6), one O(7), and one O(8) atom to form a mixture of edge and corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 46-54°. In the fourth Ti site, Ti(4) is bonded to one O(1), one O(13), one O(15), one O(7), and two equivalent O(5) atoms to form a mixture of edge and corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 47-52°. In the fifth Ti site, Ti(5) is bonded to one O(11), one O(12), one O(14), one O(3), one O(8), and one O(9) atom to form a mixture of edge and corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 44-61°. In the sixth Ti site, Ti(6) is bonded to one O(11), one O(15), one O(6), one O(7), and two equivalent O(13) atoms to form a mixture of edge and corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 49-52°. In the seventh Ti site, Ti(7) is bonded to one O(1), one O(10), one O(2), one O(4), one O(8), and one O(9) atom to form a mixture of edge and corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 42-61°. In the eighth Ti site, Ti(8) is bonded to one O(1), one O(11), one O(15), one O(2), one O(3), and one O(6) atom to form a mixture of edge and corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 42-53°. There are fifteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ti(4), one Ti(7), and one Ti(8) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Ti(3), one Ti(7), and one Ti(8) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Ti(2), one Ti(5), and one Ti(8) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Ti(1), one Ti(2), and one Ti(7) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ti(3) and two equivalent Ti(4) atoms. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Ti(3), one Ti(6), and one Ti(8) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Ti(3), one Ti(4), and one Ti(6) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Ti(3), one Ti(5), and one Ti(7) atom. In the ninth O site, O(9) is bonded to one Ti(1), one Ti(2), one Ti(5), and one Ti(7) atom to form distorted edge-sharing OTi4 trigonal pyramids. In the tenth O site, O(10) is bonded to one Ti(1), one Ti(7), and two equivalent Ti(2) atoms to form a mixture of distorted edge and corner-sharing OTi4 trigonal pyramids. In the eleventh O site, O(11) is bonded in a trigonal planar geometry to one Ti(5), one Ti(6), and one Ti(8) atom. In the twelfth O site, O(12) is bonded to one Ti(2), one Ti(5), and two equivalent Ti(1) atoms to form a mixture of distorted edge and corner-sharing OTi4 trigonal pyramids. In the thirteenth O site, O(13) is bonded in a distorted trigonal planar geometry to one Ti(4) and two equivalent Ti(6) atoms. In the fourteenth O site, O(14) is bonded in a trigonal planar geometry to one Ti(1), one Ti(3), and one Ti(5) atom. In the fifteenth O site, O(15) is bonded in a distorted trigonal planar geometry to one Ti(4), one Ti(6), and one Ti(8) atom.
Ti8O15 crystallizes in the triclinic P-1 space group. There are eight inequivalent Ti sites. In the first Ti site, Ti(1) is bonded in a 6-coordinate geometry to one O(10), one O(14), one O(4), one O(9), and two equivalent O(12) atoms. The Ti(1)-O(10) bond length is 2.00 Å. The Ti(1)-O(14) bond length is 1.88 Å. The Ti(1)-O(4) bond length is 1.84 Å. The Ti(1)-O(9) bond length is 2.13 Å. There is one shorter (1.97 Å) and one longer (2.21 Å) Ti(1)-O(12) bond length. In the second Ti site, Ti(2) is bonded to one O(12), one O(3), one O(4), one O(9), and two equivalent O(10) atoms to form a mixture of distorted edge and corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 44-52°. The Ti(2)-O(12) bond length is 2.06 Å. The Ti(2)-O(3) bond length is 1.83 Å. The Ti(2)-O(4) bond length is 1.95 Å. The Ti(2)-O(9) bond length is 2.03 Å. There is one shorter (1.99 Å) and one longer (2.18 Å) Ti(2)-O(10) bond length. In the third Ti site, Ti(3) is bonded to one O(14), one O(2), one O(5), one O(6), one O(7), and one O(8) atom to form a mixture of edge and corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 46-54°. The Ti(3)-O(14) bond length is 2.10 Å. The Ti(3)-O(2) bond length is 1.97 Å. The Ti(3)-O(5) bond length is 1.92 Å. The Ti(3)-O(6) bond length is 1.95 Å. The Ti(3)-O(7) bond length is 1.93 Å. The Ti(3)-O(8) bond length is 2.00 Å. In the fourth Ti site, Ti(4) is bonded to one O(1), one O(13), one O(15), one O(7), and two equivalent O(5) atoms to form a mixture of edge and corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 47-52°. The Ti(4)-O(1) bond length is 2.05 Å. The Ti(4)-O(13) bond length is 1.98 Å. The Ti(4)-O(15) bond length is 2.02 Å. The Ti(4)-O(7) bond length is 1.99 Å. There is one shorter (1.95 Å) and one longer (1.96 Å) Ti(4)-O(5) bond length. In the fifth Ti site, Ti(5) is bonded to one O(11), one O(12), one O(14), one O(3), one O(8), and one O(9) atom to form a mixture of edge and corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 44-61°. The Ti(5)-O(11) bond length is 1.87 Å. The Ti(5)-O(12) bond length is 2.12 Å. The Ti(5)-O(14) bond length is 1.94 Å. The Ti(5)-O(3) bond length is 1.99 Å. The Ti(5)-O(8) bond length is 1.88 Å. The Ti(5)-O(9) bond length is 2.12 Å. In the sixth Ti site, Ti(6) is bonded to one O(11), one O(15), one O(6), one O(7), and two equivalent O(13) atoms to form a mixture of edge and corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 49-52°. The Ti(6)-O(11) bond length is 2.03 Å. The Ti(6)-O(15) bond length is 1.98 Å. The Ti(6)-O(6) bond length is 1.96 Å. The Ti(6)-O(7) bond length is 1.97 Å. There is one shorter (1.94 Å) and one longer (1.96 Å) Ti(6)-O(13) bond length. In the seventh Ti site, Ti(7) is bonded to one O(1), one O(10), one O(2), one O(4), one O(8), and one O(9) atom to form a mixture of edge and corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 42-61°. The Ti(7)-O(1) bond length is 1.89 Å. The Ti(7)-O(10) bond length is 2.06 Å. The Ti(7)-O(2) bond length is 1.93 Å. The Ti(7)-O(4) bond length is 2.11 Å. The Ti(7)-O(8) bond length is 1.98 Å. The Ti(7)-O(9) bond length is 2.05 Å. In the eighth Ti site, Ti(8) is bonded to one O(1), one O(11), one O(15), one O(2), one O(3), and one O(6) atom to form a mixture of edge and corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 42-53°. The Ti(8)-O(1) bond length is 1.94 Å. The Ti(8)-O(11) bond length is 2.00 Å. The Ti(8)-O(15) bond length is 1.88 Å. The Ti(8)-O(2) bond length is 1.99 Å. The Ti(8)-O(3) bond length is 2.07 Å. The Ti(8)-O(6) bond length is 1.97 Å. There are fifteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ti(4), one Ti(7), and one Ti(8) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Ti(3), one Ti(7), and one Ti(8) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Ti(2), one Ti(5), and one Ti(8) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Ti(1), one Ti(2), and one Ti(7) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Ti(3) and two equivalent Ti(4) atoms. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Ti(3), one Ti(6), and one Ti(8) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Ti(3), one Ti(4), and one Ti(6) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Ti(3), one Ti(5), and one Ti(7) atom. In the ninth O site, O(9) is bonded to one Ti(1), one Ti(2), one Ti(5), and one Ti(7) atom to form distorted edge-sharing OTi4 trigonal pyramids. In the tenth O site, O(10) is bonded to one Ti(1), one Ti(7), and two equivalent Ti(2) atoms to form a mixture of distorted edge and corner-sharing OTi4 trigonal pyramids. In the eleventh O site, O(11) is bonded in a trigonal planar geometry to one Ti(5), one Ti(6), and one Ti(8) atom. In the twelfth O site, O(12) is bonded to one Ti(2), one Ti(5), and two equivalent Ti(1) atoms to form a mixture of distorted edge and corner-sharing OTi4 trigonal pyramids. In the thirteenth O site, O(13) is bonded in a distorted trigonal planar geometry to one Ti(4) and two equivalent Ti(6) atoms. In the fourteenth O site, O(14) is bonded in a trigonal planar geometry to one Ti(1), one Ti(3), and one Ti(5) atom. In the fifteenth O site, O(15) is bonded in a distorted trigonal planar geometry to one Ti(4), one Ti(6), and one Ti(8) atom.