Sr7W4O19 crystallizes in the monoclinic C2/m space group. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 10-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and four equivalent O(6) atoms. In the second Sr site, Sr(2) is bonded in a 10-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), two equivalent O(4), and two equivalent O(6) atoms. In the third Sr site, Sr(3) is bonded in a 12-coordinate geometry to one O(7), two equivalent O(1), two equivalent O(6), three equivalent O(5), and four equivalent O(4) atoms. In the fourth Sr site, Sr(4) is bonded to two equivalent O(5), two equivalent O(7), four equivalent O(1), and four equivalent O(4) atoms to form SrO12 cuboctahedra that share corners with two equivalent Sr(4)O12 cuboctahedra, faces with two equivalent W(2)O6 octahedra, and faces with four equivalent W(1)O6 octahedra. There are two inequivalent W sites. In the first W site, W(1) is bonded to one O(3), one O(7), two equivalent O(1), and two equivalent O(4) atoms to form WO6 octahedra that share  a cornercorner with one W(1)O6 octahedra, corners with two equivalent W(2)O6 octahedra, and faces with two equivalent Sr(4)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-10°. In the second W site, W(2) is bonded to one O(2), one O(5), two equivalent O(1), and two equivalent O(6) atoms to form WO6 octahedra that share corners with two equivalent W(1)O6 octahedra and  a faceface with one Sr(4)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 10°. There are seven inequivalent O sites. In the first O site, O(7) is bonded to two equivalent Sr(3), two equivalent Sr(4), and two equivalent W(1) atoms to form distorted OSr4W2 octahedra that share corners with two equivalent O(7)Sr4W2 octahedra, corners with two equivalent O(5)Sr4W square pyramids, corners with eight equivalent O(4)Sr4W square pyramids, edges with four equivalent O(5)Sr4W square pyramids, and faces with four equivalent O(4)Sr4W square pyramids. The corner-sharing octahedra are not tilted. In the second O site, O(1) is bonded in a 6-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Sr(4), one W(1), and one W(2) atom. In the third O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), and one W(2) atom. In the fourth O site, O(3) is bonded in a 5-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), and one W(1) atom. In the fifth O site, O(4) is bonded to one Sr(2), one Sr(4), two equivalent Sr(3), and one W(1) atom to form distorted OSr4W square pyramids that share corners with two equivalent O(7)Sr4W2 octahedra, corners with three equivalent O(5)Sr4W square pyramids, corners with four equivalent O(4)Sr4W square pyramids,  an edgeedge with one O(5)Sr4W square pyramid, edges with two equivalent O(4)Sr4W square pyramids,  a faceface with one O(7)Sr4W2 octahedra,  a faceface with one O(4)Sr4W square pyramid, and  a faceface with one O(5)Sr4W square pyramid. The corner-sharing octahedral tilt angles range from 33-58°. In the sixth O site, O(5) is bonded to one Sr(4), three equivalent Sr(3), and one W(2) atom to form distorted OSr4W square pyramids that share  a cornercorner with one O(7)Sr4W2 octahedra, corners with three equivalent O(5)Sr4W square pyramids, corners with six equivalent O(4)Sr4W square pyramids, edges with two equivalent O(7)Sr4W2 octahedra, edges with two equivalent O(4)Sr4W square pyramids, edges with two equivalent O(5)Sr4W square pyramids, and faces with two equivalent O(4)Sr4W square pyramids. The corner-sharing octahedral tilt angles are 70°. In the seventh O site, O(6) is bonded in a 5-coordinate geometry to one Sr(2), one Sr(3), two equivalent Sr(1), and one W(2) atom.
Sr7W4O19 crystallizes in the monoclinic C2/m space group. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 10-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and four equivalent O(6) atoms. Both Sr(1)-O(1) bond lengths are 2.88 Å. Both Sr(1)-O(2) bond lengths are 2.86 Å. There is one shorter (2.53 Å) and one longer (2.61 Å) Sr(1)-O(3) bond length. There are two shorter (2.55 Å) and two longer (2.72 Å) Sr(1)-O(6) bond lengths. In the second Sr site, Sr(2) is bonded in a 10-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), two equivalent O(4), and two equivalent O(6) atoms. Both Sr(2)-O(1) bond lengths are 3.02 Å. There is one shorter (2.49 Å) and one longer (2.56 Å) Sr(2)-O(2) bond length. Both Sr(2)-O(3) bond lengths are 2.85 Å. Both Sr(2)-O(4) bond lengths are 2.60 Å. Both Sr(2)-O(6) bond lengths are 2.63 Å. In the third Sr site, Sr(3) is bonded in a 12-coordinate geometry to one O(7), two equivalent O(1), two equivalent O(6), three equivalent O(5), and four equivalent O(4) atoms. The Sr(3)-O(7) bond length is 2.88 Å. Both Sr(3)-O(1) bond lengths are 2.80 Å. Both Sr(3)-O(6) bond lengths are 3.06 Å. There is one shorter (2.62 Å) and two longer (2.82 Å) Sr(3)-O(5) bond lengths. There are two shorter (2.71 Å) and two longer (2.77 Å) Sr(3)-O(4) bond lengths. In the fourth Sr site, Sr(4) is bonded to two equivalent O(5), two equivalent O(7), four equivalent O(1), and four equivalent O(4) atoms to form SrO12 cuboctahedra that share corners with two equivalent Sr(4)O12 cuboctahedra, faces with two equivalent W(2)O6 octahedra, and faces with four equivalent W(1)O6 octahedra. Both Sr(4)-O(5) bond lengths are 2.77 Å. Both Sr(4)-O(7) bond lengths are 2.80 Å. All Sr(4)-O(1) bond lengths are 2.74 Å. All Sr(4)-O(4) bond lengths are 2.71 Å. There are two inequivalent W sites. In the first W site, W(1) is bonded to one O(3), one O(7), two equivalent O(1), and two equivalent O(4) atoms to form WO6 octahedra that share  a cornercorner with one W(1)O6 octahedra, corners with two equivalent W(2)O6 octahedra, and faces with two equivalent Sr(4)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-10°. The W(1)-O(3) bond length is 1.86 Å. The W(1)-O(7) bond length is 2.02 Å. Both W(1)-O(1) bond lengths are 1.99 Å. Both W(1)-O(4) bond lengths are 1.85 Å. In the second W site, W(2) is bonded to one O(2), one O(5), two equivalent O(1), and two equivalent O(6) atoms to form WO6 octahedra that share corners with two equivalent W(1)O6 octahedra and  a faceface with one Sr(4)O12 cuboctahedra. The corner-sharing octahedral tilt angles are 10°. The W(2)-O(2) bond length is 1.95 Å. The W(2)-O(5) bond length is 1.85 Å. Both W(2)-O(1) bond lengths are 2.08 Å. Both W(2)-O(6) bond lengths are 1.84 Å. There are seven inequivalent O sites. In the first O site, O(7) is bonded to two equivalent Sr(3), two equivalent Sr(4), and two equivalent W(1) atoms to form distorted OSr4W2 octahedra that share corners with two equivalent O(7)Sr4W2 octahedra, corners with two equivalent O(5)Sr4W square pyramids, corners with eight equivalent O(4)Sr4W square pyramids, edges with four equivalent O(5)Sr4W square pyramids, and faces with four equivalent O(4)Sr4W square pyramids. The corner-sharing octahedra are not tilted. In the second O site, O(1) is bonded in a 6-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Sr(4), one W(1), and one W(2) atom. In the third O site, O(2) is bonded in a 5-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), and one W(2) atom. In the fourth O site, O(3) is bonded in a 5-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), and one W(1) atom. In the fifth O site, O(4) is bonded to one Sr(2), one Sr(4), two equivalent Sr(3), and one W(1) atom to form distorted OSr4W square pyramids that share corners with two equivalent O(7)Sr4W2 octahedra, corners with three equivalent O(5)Sr4W square pyramids, corners with four equivalent O(4)Sr4W square pyramids,  an edgeedge with one O(5)Sr4W square pyramid, edges with two equivalent O(4)Sr4W square pyramids,  a faceface with one O(7)Sr4W2 octahedra,  a faceface with one O(4)Sr4W square pyramid, and  a faceface with one O(5)Sr4W square pyramid. The corner-sharing octahedral tilt angles range from 33-58°. In the sixth O site, O(5) is bonded to one Sr(4), three equivalent Sr(3), and one W(2) atom to form distorted OSr4W square pyramids that share  a cornercorner with one O(7)Sr4W2 octahedra, corners with three equivalent O(5)Sr4W square pyramids, corners with six equivalent O(4)Sr4W square pyramids, edges with two equivalent O(7)Sr4W2 octahedra, edges with two equivalent O(4)Sr4W square pyramids, edges with two equivalent O(5)Sr4W square pyramids, and faces with two equivalent O(4)Sr4W square pyramids. The corner-sharing octahedral tilt angles are 70°. In the seventh O site, O(6) is bonded in a 5-coordinate geometry to one Sr(2), one Sr(3), two equivalent Sr(1), and one W(2) atom.