Ta11O2 crystallizes in the triclinic P1 space group. There are twenty-two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a single-bond geometry to one Ta(17), one Ta(2), and one O(4) atom. In the second Ta site, Ta(2) is bonded in a 12-coordinate geometry to one Ta(1), one Ta(10), one Ta(13), one Ta(16), one Ta(19), one Ta(20), one Ta(21), one Ta(22), one Ta(3), one Ta(4), one Ta(5), and one Ta(9) atom. In the third Ta site, Ta(3) is bonded in a single-bond geometry to one Ta(2), one Ta(5), and one O(4) atom. In the fourth Ta site, Ta(4) is bonded in a 10-coordinate geometry to one Ta(11), one Ta(13), one Ta(14), one Ta(15), one Ta(17), one Ta(2), one Ta(21), one Ta(22), one Ta(5), one Ta(6), and one Ta(7) atom. In the fifth Ta site, Ta(5) is bonded in a distorted body-centered cubic geometry to one Ta(10), one Ta(12), one Ta(13), one Ta(17), one Ta(2), one Ta(3), one Ta(4), and one Ta(8) atom. In the sixth Ta site, Ta(6) is bonded in a single-bond geometry to one Ta(17), one Ta(4), and one O(2) atom. In the seventh Ta site, Ta(7) is bonded in a single-bond geometry to one Ta(13), one Ta(17), one Ta(4), and one O(1) atom. In the eighth Ta site, Ta(8) is bonded in a single-bond geometry to one Ta(13), one Ta(5), and one O(4) atom. In the ninth Ta site, Ta(9) is bonded in a single-bond geometry to one Ta(13), one Ta(17), one Ta(2), and one O(2) atom. In the tenth Ta site, Ta(10) is bonded in a linear geometry to one Ta(2), one Ta(5), one O(3), and one O(4) atom. In the eleventh Ta site, Ta(11) is bonded in a distorted bent 150 degrees geometry to one Ta(17), one Ta(4), one O(2), and one O(3) atom. In the twelfth Ta site, Ta(12) is bonded in a distorted bent 150 degrees geometry to one Ta(13), one Ta(17), one Ta(5), one O(1), and one O(3) atom. In the thirteenth Ta site, Ta(13) is bonded in a 13-coordinate geometry to one Ta(12), one Ta(15), one Ta(16), one Ta(17), one Ta(19), one Ta(2), one Ta(21), one Ta(22), one Ta(4), one Ta(5), one Ta(7), one Ta(8), and one Ta(9) atom. In the fourteenth Ta site, Ta(14) is bonded in a distorted bent 150 degrees geometry to one Ta(4), one O(1), and one O(3) atom. In the fifteenth Ta site, Ta(15) is bonded in a single-bond geometry to one Ta(13), one Ta(17), one Ta(4), and one O(1) atom. In the sixteenth Ta site, Ta(16) is bonded in a single-bond geometry to one Ta(13), one Ta(2), and one O(2) atom. In the seventeenth Ta site, Ta(17) is bonded in a 12-coordinate geometry to one Ta(1), one Ta(11), one Ta(12), one Ta(13), one Ta(15), one Ta(18), one Ta(20), one Ta(4), one Ta(5), one Ta(6), one Ta(7), and one Ta(9) atom. In the eighteenth Ta site, Ta(18) is bonded in a linear geometry to one Ta(17), one O(3), and one O(4) atom. In the nineteenth Ta site, Ta(19) is bonded in a single-bond geometry to one Ta(13), one Ta(2), and one O(2) atom. In the twentieth Ta site, Ta(20) is bonded in a single-bond geometry to one Ta(17), one Ta(2), and one O(1) atom. In the twenty-first Ta site, Ta(21) is bonded in a single-bond geometry to one Ta(13), one Ta(2), one Ta(4), and one O(1) atom. In the twenty-second Ta site, Ta(22) is bonded in a single-bond geometry to one Ta(13), one Ta(2), one Ta(4), and one O(4) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Ta(12), one Ta(14), one Ta(15), one Ta(20), one Ta(21), and one Ta(7) atom to form corner-sharing OTa6 octahedra. In the second O site, O(2) is bonded to one Ta(11), one Ta(16), one Ta(19), one Ta(6), and one Ta(9) atom to form corner-sharing OTa5 square pyramids. In the third O site, O(3) is bonded to one Ta(10), one Ta(11), one Ta(12), one Ta(14), and one Ta(18) atom to form OTa5 square pyramids that share corners with two equivalent O(1)Ta6 octahedra, corners with two equivalent O(4)Ta6 octahedra, and  a cornercorner with one O(2)Ta5 square pyramid. The corner-sharing octahedral tilt angles range from 4-45°. In the fourth O site, O(4) is bonded to one Ta(1), one Ta(10), one Ta(18), one Ta(22), one Ta(3), and one Ta(8) atom to form corner-sharing OTa6 octahedra.
Ta11O2 crystallizes in the triclinic P1 space group. There are twenty-two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a single-bond geometry to one Ta(17), one Ta(2), and one O(4) atom. The Ta(1)-Ta(17) bond length is 2.74 Å. The Ta(1)-Ta(2) bond length is 2.81 Å. The Ta(1)-O(4) bond length is 2.03 Å. In the second Ta site, Ta(2) is bonded in a 12-coordinate geometry to one Ta(1), one Ta(10), one Ta(13), one Ta(16), one Ta(19), one Ta(20), one Ta(21), one Ta(22), one Ta(3), one Ta(4), one Ta(5), and one Ta(9) atom. The Ta(2)-Ta(10) bond length is 3.26 Å. The Ta(2)-Ta(13) bond length is 3.26 Å. The Ta(2)-Ta(16) bond length is 2.89 Å. The Ta(2)-Ta(19) bond length is 2.97 Å. The Ta(2)-Ta(20) bond length is 3.06 Å. The Ta(2)-Ta(21) bond length is 2.92 Å. The Ta(2)-Ta(22) bond length is 2.79 Å. The Ta(2)-Ta(3) bond length is 3.35 Å. The Ta(2)-Ta(4) bond length is 3.07 Å. The Ta(2)-Ta(5) bond length is 2.84 Å. The Ta(2)-Ta(9) bond length is 3.19 Å. In the third Ta site, Ta(3) is bonded in a single-bond geometry to one Ta(2), one Ta(5), and one O(4) atom. The Ta(3)-Ta(5) bond length is 2.81 Å. The Ta(3)-O(4) bond length is 2.33 Å. In the fourth Ta site, Ta(4) is bonded in a 10-coordinate geometry to one Ta(11), one Ta(13), one Ta(14), one Ta(15), one Ta(17), one Ta(2), one Ta(21), one Ta(22), one Ta(5), one Ta(6), and one Ta(7) atom. The Ta(4)-Ta(11) bond length is 2.76 Å. The Ta(4)-Ta(13) bond length is 3.41 Å. The Ta(4)-Ta(14) bond length is 3.12 Å. The Ta(4)-Ta(15) bond length is 2.79 Å. The Ta(4)-Ta(17) bond length is 3.23 Å. The Ta(4)-Ta(21) bond length is 2.84 Å. The Ta(4)-Ta(22) bond length is 2.73 Å. The Ta(4)-Ta(5) bond length is 2.94 Å. The Ta(4)-Ta(6) bond length is 2.94 Å. The Ta(4)-Ta(7) bond length is 2.97 Å. In the fifth Ta site, Ta(5) is bonded in a distorted body-centered cubic geometry to one Ta(10), one Ta(12), one Ta(13), one Ta(17), one Ta(2), one Ta(3), one Ta(4), and one Ta(8) atom. The Ta(5)-Ta(10) bond length is 2.89 Å. The Ta(5)-Ta(12) bond length is 2.75 Å. The Ta(5)-Ta(13) bond length is 2.93 Å. The Ta(5)-Ta(17) bond length is 2.80 Å. The Ta(5)-Ta(8) bond length is 2.88 Å. In the sixth Ta site, Ta(6) is bonded in a single-bond geometry to one Ta(17), one Ta(4), and one O(2) atom. The Ta(6)-Ta(17) bond length is 2.89 Å. The Ta(6)-O(2) bond length is 2.28 Å. In the seventh Ta site, Ta(7) is bonded in a single-bond geometry to one Ta(13), one Ta(17), one Ta(4), and one O(1) atom. The Ta(7)-Ta(13) bond length is 2.87 Å. The Ta(7)-Ta(17) bond length is 2.90 Å. The Ta(7)-O(1) bond length is 2.36 Å. In the eighth Ta site, Ta(8) is bonded in a single-bond geometry to one Ta(13), one Ta(5), and one O(4) atom. The Ta(8)-Ta(13) bond length is 3.37 Å. The Ta(8)-O(4) bond length is 2.32 Å. In the ninth Ta site, Ta(9) is bonded in a single-bond geometry to one Ta(13), one Ta(17), one Ta(2), and one O(2) atom. The Ta(9)-Ta(13) bond length is 3.41 Å. The Ta(9)-Ta(17) bond length is 3.28 Å. The Ta(9)-O(2) bond length is 2.14 Å. In the tenth Ta site, Ta(10) is bonded in a linear geometry to one Ta(2), one Ta(5), one O(3), and one O(4) atom. The Ta(10)-O(3) bond length is 2.32 Å. The Ta(10)-O(4) bond length is 2.31 Å. In the eleventh Ta site, Ta(11) is bonded in a distorted bent 150 degrees geometry to one Ta(17), one Ta(4), one O(2), and one O(3) atom. The Ta(11)-Ta(17) bond length is 2.84 Å. The Ta(11)-O(2) bond length is 2.07 Å. The Ta(11)-O(3) bond length is 2.15 Å. In the twelfth Ta site, Ta(12) is bonded in a distorted bent 150 degrees geometry to one Ta(13), one Ta(17), one Ta(5), one O(1), and one O(3) atom. The Ta(12)-Ta(13) bond length is 3.26 Å. The Ta(12)-Ta(17) bond length is 3.47 Å. The Ta(12)-O(1) bond length is 2.04 Å. The Ta(12)-O(3) bond length is 2.02 Å. In the thirteenth Ta site, Ta(13) is bonded in a 13-coordinate geometry to one Ta(12), one Ta(15), one Ta(16), one Ta(17), one Ta(19), one Ta(2), one Ta(21), one Ta(22), one Ta(4), one Ta(5), one Ta(7), one Ta(8), and one Ta(9) atom. The Ta(13)-Ta(15) bond length is 2.85 Å. The Ta(13)-Ta(16) bond length is 2.93 Å. The Ta(13)-Ta(17) bond length is 3.12 Å. The Ta(13)-Ta(19) bond length is 2.94 Å. The Ta(13)-Ta(21) bond length is 2.92 Å. The Ta(13)-Ta(22) bond length is 2.81 Å. In the fourteenth Ta site, Ta(14) is bonded in a distorted bent 150 degrees geometry to one Ta(4), one O(1), and one O(3) atom. The Ta(14)-O(1) bond length is 2.04 Å. The Ta(14)-O(3) bond length is 2.03 Å. In the fifteenth Ta site, Ta(15) is bonded in a single-bond geometry to one Ta(13), one Ta(17), one Ta(4), and one O(1) atom. The Ta(15)-Ta(17) bond length is 2.98 Å. The Ta(15)-O(1) bond length is 2.37 Å. In the sixteenth Ta site, Ta(16) is bonded in a single-bond geometry to one Ta(13), one Ta(2), and one O(2) atom. The Ta(16)-O(2) bond length is 2.25 Å. In the seventeenth Ta site, Ta(17) is bonded in a 12-coordinate geometry to one Ta(1), one Ta(11), one Ta(12), one Ta(13), one Ta(15), one Ta(18), one Ta(20), one Ta(4), one Ta(5), one Ta(6), one Ta(7), and one Ta(9) atom. The Ta(17)-Ta(18) bond length is 3.35 Å. The Ta(17)-Ta(20) bond length is 3.03 Å. In the eighteenth Ta site, Ta(18) is bonded in a linear geometry to one Ta(17), one O(3), and one O(4) atom. The Ta(18)-O(3) bond length is 2.33 Å. The Ta(18)-O(4) bond length is 2.36 Å. In the nineteenth Ta site, Ta(19) is bonded in a single-bond geometry to one Ta(13), one Ta(2), and one O(2) atom. The Ta(19)-O(2) bond length is 2.14 Å. In the twentieth Ta site, Ta(20) is bonded in a single-bond geometry to one Ta(17), one Ta(2), and one O(1) atom. The Ta(20)-O(1) bond length is 2.23 Å. In the twenty-first Ta site, Ta(21) is bonded in a single-bond geometry to one Ta(13), one Ta(2), one Ta(4), and one O(1) atom. The Ta(21)-O(1) bond length is 2.27 Å. In the twenty-second Ta site, Ta(22) is bonded in a single-bond geometry to one Ta(13), one Ta(2), one Ta(4), and one O(4) atom. The Ta(22)-O(4) bond length is 2.06 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Ta(12), one Ta(14), one Ta(15), one Ta(20), one Ta(21), and one Ta(7) atom to form corner-sharing OTa6 octahedra. In the second O site, O(2) is bonded to one Ta(11), one Ta(16), one Ta(19), one Ta(6), and one Ta(9) atom to form corner-sharing OTa5 square pyramids. In the third O site, O(3) is bonded to one Ta(10), one Ta(11), one Ta(12), one Ta(14), and one Ta(18) atom to form OTa5 square pyramids that share corners with two equivalent O(1)Ta6 octahedra, corners with two equivalent O(4)Ta6 octahedra, and  a cornercorner with one O(2)Ta5 square pyramid. The corner-sharing octahedral tilt angles range from 4-45°. In the fourth O site, O(4) is bonded to one Ta(1), one Ta(10), one Ta(18), one Ta(22), one Ta(3), and one Ta(8) atom to form corner-sharing OTa6 octahedra.