H2W2O7 crystallizes in the orthorhombic Ima2 space group. There are two inequivalent W sites. In the first W site, W(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. In the second W site, W(2) is bonded to one O(5), two equivalent O(1), and two equivalent O(4) atoms to form distorted corner-sharing WO5 trigonal bipyramids. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(3) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(4) atom. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one W(1) and one W(2) atom. In the second O site, O(2) is bonded in a single-bond geometry to one W(1) atom. In the third O site, O(3) is bonded in a single-bond geometry to two equivalent W(1) and one H(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to two equivalent W(2) and one H(2) atom. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one W(2) and two equivalent W(1) atoms.
H2W2O7 crystallizes in the orthorhombic Ima2 space group. There are two inequivalent W sites. In the first W site, W(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(5) atoms. Both W(1)-O(1) bond lengths are 2.38 Å. Both W(1)-O(2) bond lengths are 1.79 Å. Both W(1)-O(3) bond lengths are 2.20 Å. Both W(1)-O(5) bond lengths are 2.17 Å. In the second W site, W(2) is bonded to one O(5), two equivalent O(1), and two equivalent O(4) atoms to form distorted corner-sharing WO5 trigonal bipyramids. The W(2)-O(5) bond length is 1.96 Å. Both W(2)-O(1) bond lengths are 1.78 Å. There is one shorter (2.07 Å) and one longer (2.10 Å) W(2)-O(4) bond length. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(3) atom. The H(1)-O(3) bond length is 0.98 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(4) atom. The H(2)-O(4) bond length is 0.98 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one W(1) and one W(2) atom. In the second O site, O(2) is bonded in a single-bond geometry to one W(1) atom. In the third O site, O(3) is bonded in a single-bond geometry to two equivalent W(1) and one H(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to two equivalent W(2) and one H(2) atom. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one W(2) and two equivalent W(1) atoms.