Ta2W2O11 crystallizes in the monoclinic C2 space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(11), one O(4), one O(8), and two equivalent O(6) atoms to form distorted TaO5 trigonal bipyramids that share corners with two equivalent W(3)O6 octahedra,  a cornercorner with one Ta(2)O5 trigonal bipyramid, and corners with two equivalent Ta(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 29-42°. In the second Ta site, Ta(2) is bonded to one O(10), one O(2), one O(5), one O(7), and one O(8) atom to form TaO5 trigonal bipyramids that share  a cornercorner with one W(1)O6 octahedra,  a cornercorner with one W(3)O6 octahedra, corners with two equivalent W(2)O6 octahedra, and  a cornercorner with one Ta(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 23-44°. There are three inequivalent W sites. In the first W site, W(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(7) atoms to form WO6 octahedra that share corners with four equivalent W(2)O6 octahedra and corners with two equivalent Ta(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 34-38°. In the second W site, W(2) is bonded to one O(1), one O(10), one O(3), one O(5), and two equivalent O(9) atoms to form WO6 octahedra that share corners with two equivalent W(1)O6 octahedra, corners with two equivalent W(2)O6 octahedra, and corners with two equivalent Ta(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 34-38°. In the third W site, W(3) is bonded to two equivalent O(11), two equivalent O(2), and two equivalent O(4) atoms to form WO6 octahedra that share corners with two equivalent Ta(2)O5 trigonal bipyramids and corners with four equivalent Ta(1)O5 trigonal bipyramids. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one W(1) and one W(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Ta(2) and one W(3) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one W(1) and one W(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Ta(1) and one W(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Ta(2) and one W(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to two equivalent Ta(1) atoms. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Ta(2) and one W(1) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Ta(1) and one Ta(2) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to two equivalent W(2) atoms. In the tenth O site, O(10) is bonded in a distorted bent 150 degrees geometry to one Ta(2) and one W(2) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Ta(1) and one W(3) atom.
Ta2W2O11 crystallizes in the monoclinic C2 space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(11), one O(4), one O(8), and two equivalent O(6) atoms to form distorted TaO5 trigonal bipyramids that share corners with two equivalent W(3)O6 octahedra,  a cornercorner with one Ta(2)O5 trigonal bipyramid, and corners with two equivalent Ta(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 29-42°. The Ta(1)-O(11) bond length is 1.94 Å. The Ta(1)-O(4) bond length is 1.99 Å. The Ta(1)-O(8) bond length is 1.87 Å. Both Ta(1)-O(6) bond lengths are 1.96 Å. In the second Ta site, Ta(2) is bonded to one O(10), one O(2), one O(5), one O(7), and one O(8) atom to form TaO5 trigonal bipyramids that share  a cornercorner with one W(1)O6 octahedra,  a cornercorner with one W(3)O6 octahedra, corners with two equivalent W(2)O6 octahedra, and  a cornercorner with one Ta(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 23-44°. The Ta(2)-O(10) bond length is 1.82 Å. The Ta(2)-O(2) bond length is 1.91 Å. The Ta(2)-O(5) bond length is 2.04 Å. The Ta(2)-O(7) bond length is 1.95 Å. The Ta(2)-O(8) bond length is 1.99 Å. There are three inequivalent W sites. In the first W site, W(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(7) atoms to form WO6 octahedra that share corners with four equivalent W(2)O6 octahedra and corners with two equivalent Ta(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 34-38°. Both W(1)-O(1) bond lengths are 1.91 Å. Both W(1)-O(3) bond lengths are 1.97 Å. Both W(1)-O(7) bond lengths are 1.93 Å. In the second W site, W(2) is bonded to one O(1), one O(10), one O(3), one O(5), and two equivalent O(9) atoms to form WO6 octahedra that share corners with two equivalent W(1)O6 octahedra, corners with two equivalent W(2)O6 octahedra, and corners with two equivalent Ta(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 34-38°. The W(2)-O(1) bond length is 1.94 Å. The W(2)-O(10) bond length is 2.07 Å. The W(2)-O(3) bond length is 1.92 Å. The W(2)-O(5) bond length is 1.86 Å. There is one shorter (1.90 Å) and one longer (1.95 Å) W(2)-O(9) bond length. In the third W site, W(3) is bonded to two equivalent O(11), two equivalent O(2), and two equivalent O(4) atoms to form WO6 octahedra that share corners with two equivalent Ta(2)O5 trigonal bipyramids and corners with four equivalent Ta(1)O5 trigonal bipyramids. Both W(3)-O(11) bond lengths are 1.95 Å. Both W(3)-O(2) bond lengths are 1.98 Å. Both W(3)-O(4) bond lengths are 1.91 Å. There are eleven inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to one W(1) and one W(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Ta(2) and one W(3) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one W(1) and one W(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Ta(1) and one W(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Ta(2) and one W(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to two equivalent Ta(1) atoms. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Ta(2) and one W(1) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Ta(1) and one Ta(2) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to two equivalent W(2) atoms. In the tenth O site, O(10) is bonded in a distorted bent 150 degrees geometry to one Ta(2) and one W(2) atom. In the eleventh O site, O(11) is bonded in a bent 150 degrees geometry to one Ta(1) and one W(3) atom.