W2Al2O7 crystallizes in the triclinic P1 space group. There are four inequivalent W sites. In the first W site, W(1) is bonded in a 6-coordinate geometry to one O(10), one O(14), one O(4), one O(5), one O(7), and one O(9) atom. In the second W site, W(2) is bonded to one O(10), one O(12), one O(13), one O(3), one O(7), and one O(8) atom to form distorted WO6 octahedra that share  a cornercorner with one Al(4)O4 tetrahedra, corners with two equivalent Al(3)O5 trigonal bipyramids,  an edgeedge with one Al(4)O4 tetrahedra, and  an edgeedge with one Al(1)O5 trigonal bipyramid. In the third W site, W(3) is bonded in a 5-coordinate geometry to one O(13), one O(4), one O(6), one O(8), and one O(9) atom. In the fourth W site, W(4) is bonded in a 5-coordinate geometry to one O(11), one O(12), one O(14), one O(5), and one O(6) atom. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(11), one O(13), one O(2), and one O(3) atom to form distorted AlO5 trigonal bipyramids that share  a cornercorner with one Al(4)O4 tetrahedra,  a cornercorner with one Al(3)O5 trigonal bipyramid,  an edgeedge with one W(2)O6 octahedra,  an edgeedge with one Al(2)O5 trigonal bipyramid, and  an edgeedge with one Al(3)O5 trigonal bipyramid. In the second Al site, Al(2) is bonded to one O(11), one O(14), one O(2), one O(6), and one O(9) atom to form a mixture of corner and edge-sharing AlO5 trigonal bipyramids. In the third Al site, Al(3) is bonded to one O(1), one O(12), one O(2), one O(3), and one O(5) atom to form AlO5 trigonal bipyramids that share corners with two equivalent W(2)O6 octahedra,  a cornercorner with one Al(4)O4 tetrahedra,  a cornercorner with one Al(1)O5 trigonal bipyramid,  a cornercorner with one Al(2)O5 trigonal bipyramid, and  an edgeedge with one Al(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 55°. In the fourth Al site, Al(4) is bonded to one O(1), one O(10), one O(7), and one O(8) atom to form distorted AlO4 tetrahedra that share  a cornercorner with one W(2)O6 octahedra,  a cornercorner with one Al(1)O5 trigonal bipyramid,  a cornercorner with one Al(3)O5 trigonal bipyramid, and  an edgeedge with one W(2)O6 octahedra. The corner-sharing octahedral tilt angles are 60°. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Al(1), one Al(3), and one Al(4) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(2), and one Al(3) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one W(2), one Al(1), and one Al(3) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one W(1) and one W(3) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one W(1), one W(4), and one Al(3) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one W(3), one W(4), and one Al(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one W(1), one W(2), and one Al(4) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one W(2), one W(3), and one Al(4) atom. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one W(1), one W(3), and one Al(2) atom. In the tenth O site, O(10) is bonded in a distorted trigonal non-coplanar geometry to one W(1), one W(2), and one Al(4) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one W(4), one Al(1), and one Al(2) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one W(2), one W(4), and one Al(3) atom. In the thirteenth O site, O(13) is bonded in a distorted trigonal planar geometry to one W(2), one W(3), and one Al(1) atom. In the fourteenth O site, O(14) is bonded in a distorted trigonal non-coplanar geometry to one W(1), one W(4), and one Al(2) atom.
W2Al2O7 crystallizes in the triclinic P1 space group. There are four inequivalent W sites. In the first W site, W(1) is bonded in a 6-coordinate geometry to one O(10), one O(14), one O(4), one O(5), one O(7), and one O(9) atom. The W(1)-O(10) bond length is 2.11 Å. The W(1)-O(14) bond length is 1.97 Å. The W(1)-O(4) bond length is 1.92 Å. The W(1)-O(5) bond length is 2.09 Å. The W(1)-O(7) bond length is 2.27 Å. The W(1)-O(9) bond length is 2.20 Å. In the second W site, W(2) is bonded to one O(10), one O(12), one O(13), one O(3), one O(7), and one O(8) atom to form distorted WO6 octahedra that share  a cornercorner with one Al(4)O4 tetrahedra, corners with two equivalent Al(3)O5 trigonal bipyramids,  an edgeedge with one Al(4)O4 tetrahedra, and  an edgeedge with one Al(1)O5 trigonal bipyramid. The W(2)-O(10) bond length is 2.06 Å. The W(2)-O(12) bond length is 2.18 Å. The W(2)-O(13) bond length is 2.23 Å. The W(2)-O(3) bond length is 2.02 Å. The W(2)-O(7) bond length is 2.05 Å. The W(2)-O(8) bond length is 2.13 Å. In the third W site, W(3) is bonded in a 5-coordinate geometry to one O(13), one O(4), one O(6), one O(8), and one O(9) atom. The W(3)-O(13) bond length is 2.06 Å. The W(3)-O(4) bond length is 1.89 Å. The W(3)-O(6) bond length is 2.16 Å. The W(3)-O(8) bond length is 2.09 Å. The W(3)-O(9) bond length is 1.95 Å. In the fourth W site, W(4) is bonded in a 5-coordinate geometry to one O(11), one O(12), one O(14), one O(5), and one O(6) atom. The W(4)-O(11) bond length is 1.99 Å. The W(4)-O(12) bond length is 1.99 Å. The W(4)-O(14) bond length is 2.09 Å. The W(4)-O(5) bond length is 2.13 Å. The W(4)-O(6) bond length is 1.99 Å. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(11), one O(13), one O(2), and one O(3) atom to form distorted AlO5 trigonal bipyramids that share  a cornercorner with one Al(4)O4 tetrahedra,  a cornercorner with one Al(3)O5 trigonal bipyramid,  an edgeedge with one W(2)O6 octahedra,  an edgeedge with one Al(2)O5 trigonal bipyramid, and  an edgeedge with one Al(3)O5 trigonal bipyramid. The Al(1)-O(1) bond length is 1.86 Å. The Al(1)-O(11) bond length is 1.84 Å. The Al(1)-O(13) bond length is 1.86 Å. The Al(1)-O(2) bond length is 1.89 Å. The Al(1)-O(3) bond length is 2.05 Å. In the second Al site, Al(2) is bonded to one O(11), one O(14), one O(2), one O(6), and one O(9) atom to form a mixture of corner and edge-sharing AlO5 trigonal bipyramids. The Al(2)-O(11) bond length is 1.85 Å. The Al(2)-O(14) bond length is 1.97 Å. The Al(2)-O(2) bond length is 1.80 Å. The Al(2)-O(6) bond length is 1.87 Å. The Al(2)-O(9) bond length is 1.85 Å. In the third Al site, Al(3) is bonded to one O(1), one O(12), one O(2), one O(3), and one O(5) atom to form AlO5 trigonal bipyramids that share corners with two equivalent W(2)O6 octahedra,  a cornercorner with one Al(4)O4 tetrahedra,  a cornercorner with one Al(1)O5 trigonal bipyramid,  a cornercorner with one Al(2)O5 trigonal bipyramid, and  an edgeedge with one Al(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 55°. The Al(3)-O(1) bond length is 1.98 Å. The Al(3)-O(12) bond length is 1.97 Å. The Al(3)-O(2) bond length is 1.82 Å. The Al(3)-O(3) bond length is 1.97 Å. The Al(3)-O(5) bond length is 1.91 Å. In the fourth Al site, Al(4) is bonded to one O(1), one O(10), one O(7), and one O(8) atom to form distorted AlO4 tetrahedra that share  a cornercorner with one W(2)O6 octahedra,  a cornercorner with one Al(1)O5 trigonal bipyramid,  a cornercorner with one Al(3)O5 trigonal bipyramid, and  an edgeedge with one W(2)O6 octahedra. The corner-sharing octahedral tilt angles are 60°. The Al(4)-O(1) bond length is 1.82 Å. The Al(4)-O(10) bond length is 1.95 Å. The Al(4)-O(7) bond length is 1.89 Å. The Al(4)-O(8) bond length is 1.80 Å. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Al(1), one Al(3), and one Al(4) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(2), and one Al(3) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one W(2), one Al(1), and one Al(3) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to one W(1) and one W(3) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one W(1), one W(4), and one Al(3) atom. In the sixth O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one W(3), one W(4), and one Al(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one W(1), one W(2), and one Al(4) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one W(2), one W(3), and one Al(4) atom. In the ninth O site, O(9) is bonded in a distorted T-shaped geometry to one W(1), one W(3), and one Al(2) atom. In the tenth O site, O(10) is bonded in a distorted trigonal non-coplanar geometry to one W(1), one W(2), and one Al(4) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one W(4), one Al(1), and one Al(2) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one W(2), one W(4), and one Al(3) atom. In the thirteenth O site, O(13) is bonded in a distorted trigonal planar geometry to one W(2), one W(3), and one Al(1) atom. In the fourteenth O site, O(14) is bonded in a distorted trigonal non-coplanar geometry to one W(1), one W(4), and one Al(2) atom.