Sr3U(Te2O7)2 crystallizes in the monoclinic C2/c space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one O(1), one O(2), one O(3), two equivalent O(4), and two equivalent O(5) atoms to form distorted SrO7 pentagonal bipyramids that share  a cornercorner with one U(1)O6 octahedra and edges with two equivalent Sr(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 70°. In the second Sr site, Sr(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms. U(1) is bonded to two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms to form UO6 octahedra that share corners with two equivalent Sr(1)O7 pentagonal bipyramids. There are two inequivalent Te sites. In the first Te site, Te(1) is bonded in a 3-coordinate geometry to one O(1), one O(3), and one O(6) atom. In the second Te site, Te(2) is bonded in a distorted trigonal non-coplanar geometry to one O(2), one O(4), and one O(5) atom. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Sr(1), one Sr(2), and one Te(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sr(1), one Sr(2), and one Te(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Sr(1), one U(1), and one Te(1) atom. In the fourth O site, O(4) is bonded to one Sr(2), two equivalent Sr(1), and one Te(2) atom to form a mixture of distorted edge and corner-sharing OSr3Te tetrahedra. In the fifth O site, O(5) is bonded to one Sr(2), two equivalent Sr(1), and one Te(2) atom to form a mixture of distorted edge and corner-sharing OSr3Te trigonal pyramids. In the sixth O site, O(6) is bonded in a linear geometry to one U(1) and one Te(1) atom. In the seventh O site, O(7) is bonded in a single-bond geometry to one U(1) atom.
Sr3U(Te2O7)2 crystallizes in the monoclinic C2/c space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one O(1), one O(2), one O(3), two equivalent O(4), and two equivalent O(5) atoms to form distorted SrO7 pentagonal bipyramids that share  a cornercorner with one U(1)O6 octahedra and edges with two equivalent Sr(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 70°. The Sr(1)-O(1) bond length is 2.58 Å. The Sr(1)-O(2) bond length is 2.51 Å. The Sr(1)-O(3) bond length is 2.71 Å. There is one shorter (2.49 Å) and one longer (2.64 Å) Sr(1)-O(4) bond length. There is one shorter (2.66 Å) and one longer (2.73 Å) Sr(1)-O(5) bond length. In the second Sr site, Sr(2) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms. Both Sr(2)-O(1) bond lengths are 2.63 Å. Both Sr(2)-O(2) bond lengths are 2.80 Å. Both Sr(2)-O(4) bond lengths are 2.62 Å. Both Sr(2)-O(5) bond lengths are 2.59 Å. U(1) is bonded to two equivalent O(3), two equivalent O(6), and two equivalent O(7) atoms to form UO6 octahedra that share corners with two equivalent Sr(1)O7 pentagonal bipyramids. Both U(1)-O(3) bond lengths are 2.28 Å. Both U(1)-O(6) bond lengths are 2.25 Å. Both U(1)-O(7) bond lengths are 1.86 Å. There are two inequivalent Te sites. In the first Te site, Te(1) is bonded in a 3-coordinate geometry to one O(1), one O(3), and one O(6) atom. The Te(1)-O(1) bond length is 1.87 Å. The Te(1)-O(3) bond length is 1.94 Å. The Te(1)-O(6) bond length is 1.92 Å. In the second Te site, Te(2) is bonded in a distorted trigonal non-coplanar geometry to one O(2), one O(4), and one O(5) atom. The Te(2)-O(2) bond length is 1.90 Å. The Te(2)-O(4) bond length is 1.89 Å. The Te(2)-O(5) bond length is 1.90 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Sr(1), one Sr(2), and one Te(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sr(1), one Sr(2), and one Te(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Sr(1), one U(1), and one Te(1) atom. In the fourth O site, O(4) is bonded to one Sr(2), two equivalent Sr(1), and one Te(2) atom to form a mixture of distorted edge and corner-sharing OSr3Te tetrahedra. In the fifth O site, O(5) is bonded to one Sr(2), two equivalent Sr(1), and one Te(2) atom to form a mixture of distorted edge and corner-sharing OSr3Te trigonal pyramids. In the sixth O site, O(6) is bonded in a linear geometry to one U(1) and one Te(1) atom. In the seventh O site, O(7) is bonded in a single-bond geometry to one U(1) atom.