Sr6Mg(W2O9)2 crystallizes in the triclinic P1 space group. There are six inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to one O(1), one O(10), one O(18), one O(2), one O(3), and one O(5) atom. In the second Sr site, Sr(2) is bonded to one O(10), one O(14), one O(2), one O(4), one O(6), and one O(7) atom to form distorted SrO6 pentagonal pyramids that share corners with two equivalent W(2)O6 octahedra, corners with two equivalent W(4)O6 octahedra,  an edgeedge with one W(1)O6 octahedra, and  an edgeedge with one W(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-66°. In the third Sr site, Sr(3) is bonded in a 5-coordinate geometry to one O(1), one O(13), one O(14), one O(3), one O(8), and one O(9) atom. In the fourth Sr site, Sr(4) is bonded in a 7-coordinate geometry to one O(10), one O(13), one O(14), one O(16), one O(17), one O(18), and one O(7) atom. In the fifth Sr site, Sr(5) is bonded in a 6-coordinate geometry to one O(12), one O(15), one O(2), one O(4), one O(6), and one O(9) atom. In the sixth Sr site, Sr(6) is bonded to one O(11), one O(12), one O(16), one O(17), one O(8), and one O(9) atom to form distorted SrO6 octahedra that share corners with two equivalent W(1)O6 octahedra, corners with two equivalent W(3)O6 octahedra,  an edgeedge with one W(2)O6 octahedra, and  an edgeedge with one W(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-71°. Mg(1) is bonded in a rectangular see-saw-like geometry to one O(11), one O(13), one O(15), and one O(17) atom. There are four inequivalent W sites. In the first W site, W(1) is bonded to one O(12), one O(14), one O(18), one O(2), one O(3), and one O(9) atom to form distorted WO6 octahedra that share corners with two equivalent Sr(6)O6 octahedra,  an edgeedge with one Sr(2)O6 pentagonal pyramid, and  a faceface with one W(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-71°. In the second W site, W(2) is bonded to one O(11), one O(13), one O(16), one O(4), one O(5), and one O(6) atom to form distorted WO6 octahedra that share corners with two equivalent Sr(2)O6 pentagonal pyramids,  an edgeedge with one Sr(6)O6 octahedra, and  a faceface with one W(3)O6 octahedra. In the third W site, W(3) is bonded to one O(1), one O(10), one O(16), one O(17), one O(5), and one O(6) atom to form distorted WO6 octahedra that share corners with two equivalent Sr(6)O6 octahedra,  an edgeedge with one Sr(2)O6 pentagonal pyramid, and  a faceface with one W(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-59°. In the fourth W site, W(4) is bonded to one O(12), one O(14), one O(15), one O(3), one O(7), and one O(8) atom to form distorted WO6 octahedra that share corners with two equivalent Sr(2)O6 pentagonal pyramids,  an edgeedge with one Sr(6)O6 octahedra, and  a faceface with one W(1)O6 octahedra. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(3), and one W(3) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Sr(1), one Sr(2), one Sr(5), and one W(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(3), one W(1), and one W(4) atom. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Sr(2), one Sr(5), and one W(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Sr(1), one W(2), and one W(3) atom. In the sixth O site, O(6) is bonded in a distorted see-saw-like geometry to one Sr(2), one Sr(5), one W(2), and one W(3) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Sr(2), one Sr(4), and one W(4) atom. In the eighth O site, O(8) is bonded in a distorted trigonal non-coplanar geometry to one Sr(3), one Sr(6), and one W(4) atom. In the ninth O site, O(9) is bonded to one Sr(3), one Sr(5), one Sr(6), and one W(1) atom to form distorted corner-sharing OSr3W tetrahedra. In the tenth O site, O(10) is bonded to one Sr(1), one Sr(2), one Sr(4), and one W(3) atom to form corner-sharing OSr3W tetrahedra. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Sr(6), one Mg(1), and one W(2) atom. In the twelfth O site, O(12) is bonded in a rectangular see-saw-like geometry to one Sr(5), one Sr(6), one W(1), and one W(4) atom. In the thirteenth O site, O(13) is bonded to one Sr(3), one Sr(4), one Mg(1), and one W(2) atom to form distorted corner-sharing OSr2MgW tetrahedra. In the fourteenth O site, O(14) is bonded in a 5-coordinate geometry to one Sr(2), one Sr(3), one Sr(4), one W(1), and one W(4) atom. In the fifteenth O site, O(15) is bonded in a 3-coordinate geometry to one Sr(5), one Mg(1), and one W(4) atom. In the sixteenth O site, O(16) is bonded in a rectangular see-saw-like geometry to one Sr(4), one Sr(6), one W(2), and one W(3) atom. In the seventeenth O site, O(17) is bonded in a distorted rectangular see-saw-like geometry to one Sr(4), one Sr(6), one Mg(1), and one W(3) atom. In the eighteenth O site, O(18) is bonded in a 3-coordinate geometry to one Sr(1), one Sr(4), and one W(1) atom.
Sr6Mg(W2O9)2 crystallizes in the triclinic P1 space group. There are six inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to one O(1), one O(10), one O(18), one O(2), one O(3), and one O(5) atom. The Sr(1)-O(1) bond length is 2.86 Å. The Sr(1)-O(10) bond length is 2.37 Å. The Sr(1)-O(18) bond length is 2.79 Å. The Sr(1)-O(2) bond length is 2.62 Å. The Sr(1)-O(3) bond length is 2.69 Å. The Sr(1)-O(5) bond length is 2.44 Å. In the second Sr site, Sr(2) is bonded to one O(10), one O(14), one O(2), one O(4), one O(6), and one O(7) atom to form distorted SrO6 pentagonal pyramids that share corners with two equivalent W(2)O6 octahedra, corners with two equivalent W(4)O6 octahedra,  an edgeedge with one W(1)O6 octahedra, and  an edgeedge with one W(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-66°. The Sr(2)-O(10) bond length is 2.42 Å. The Sr(2)-O(14) bond length is 2.65 Å. The Sr(2)-O(2) bond length is 2.58 Å. The Sr(2)-O(4) bond length is 2.53 Å. The Sr(2)-O(6) bond length is 2.58 Å. The Sr(2)-O(7) bond length is 2.52 Å. In the third Sr site, Sr(3) is bonded in a 5-coordinate geometry to one O(1), one O(13), one O(14), one O(3), one O(8), and one O(9) atom. The Sr(3)-O(1) bond length is 2.52 Å. The Sr(3)-O(13) bond length is 2.40 Å. The Sr(3)-O(14) bond length is 3.04 Å. The Sr(3)-O(3) bond length is 2.61 Å. The Sr(3)-O(8) bond length is 2.52 Å. The Sr(3)-O(9) bond length is 2.50 Å. In the fourth Sr site, Sr(4) is bonded in a 7-coordinate geometry to one O(10), one O(13), one O(14), one O(16), one O(17), one O(18), and one O(7) atom. The Sr(4)-O(10) bond length is 2.67 Å. The Sr(4)-O(13) bond length is 2.52 Å. The Sr(4)-O(14) bond length is 2.88 Å. The Sr(4)-O(16) bond length is 2.66 Å. The Sr(4)-O(17) bond length is 2.54 Å. The Sr(4)-O(18) bond length is 2.69 Å. The Sr(4)-O(7) bond length is 2.71 Å. In the fifth Sr site, Sr(5) is bonded in a 6-coordinate geometry to one O(12), one O(15), one O(2), one O(4), one O(6), and one O(9) atom. The Sr(5)-O(12) bond length is 2.61 Å. The Sr(5)-O(15) bond length is 2.61 Å. The Sr(5)-O(2) bond length is 2.90 Å. The Sr(5)-O(4) bond length is 2.39 Å. The Sr(5)-O(6) bond length is 2.46 Å. The Sr(5)-O(9) bond length is 2.53 Å. In the sixth Sr site, Sr(6) is bonded to one O(11), one O(12), one O(16), one O(17), one O(8), and one O(9) atom to form distorted SrO6 octahedra that share corners with two equivalent W(1)O6 octahedra, corners with two equivalent W(3)O6 octahedra,  an edgeedge with one W(2)O6 octahedra, and  an edgeedge with one W(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-71°. The Sr(6)-O(11) bond length is 2.44 Å. The Sr(6)-O(12) bond length is 2.53 Å. The Sr(6)-O(16) bond length is 2.59 Å. The Sr(6)-O(17) bond length is 2.48 Å. The Sr(6)-O(8) bond length is 2.53 Å. The Sr(6)-O(9) bond length is 2.59 Å. Mg(1) is bonded in a rectangular see-saw-like geometry to one O(11), one O(13), one O(15), and one O(17) atom. The Mg(1)-O(11) bond length is 2.01 Å. The Mg(1)-O(13) bond length is 2.00 Å. The Mg(1)-O(15) bond length is 1.97 Å. The Mg(1)-O(17) bond length is 1.96 Å. There are four inequivalent W sites. In the first W site, W(1) is bonded to one O(12), one O(14), one O(18), one O(2), one O(3), and one O(9) atom to form distorted WO6 octahedra that share corners with two equivalent Sr(6)O6 octahedra,  an edgeedge with one Sr(2)O6 pentagonal pyramid, and  a faceface with one W(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-71°. The W(1)-O(12) bond length is 2.04 Å. The W(1)-O(14) bond length is 2.19 Å. The W(1)-O(18) bond length is 1.82 Å. The W(1)-O(2) bond length is 1.87 Å. The W(1)-O(3) bond length is 2.11 Å. The W(1)-O(9) bond length is 1.90 Å. In the second W site, W(2) is bonded to one O(11), one O(13), one O(16), one O(4), one O(5), and one O(6) atom to form distorted WO6 octahedra that share corners with two equivalent Sr(2)O6 pentagonal pyramids,  an edgeedge with one Sr(6)O6 octahedra, and  a faceface with one W(3)O6 octahedra. The W(2)-O(11) bond length is 1.99 Å. The W(2)-O(13) bond length is 2.03 Å. The W(2)-O(16) bond length is 2.09 Å. The W(2)-O(4) bond length is 1.89 Å. The W(2)-O(5) bond length is 2.07 Å. The W(2)-O(6) bond length is 2.13 Å. In the third W site, W(3) is bonded to one O(1), one O(10), one O(16), one O(17), one O(5), and one O(6) atom to form distorted WO6 octahedra that share corners with two equivalent Sr(6)O6 octahedra,  an edgeedge with one Sr(2)O6 pentagonal pyramid, and  a faceface with one W(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-59°. The W(3)-O(1) bond length is 1.87 Å. The W(3)-O(10) bond length is 2.01 Å. The W(3)-O(16) bond length is 2.18 Å. The W(3)-O(17) bond length is 2.01 Å. The W(3)-O(5) bond length is 2.06 Å. The W(3)-O(6) bond length is 2.19 Å. In the fourth W site, W(4) is bonded to one O(12), one O(14), one O(15), one O(3), one O(7), and one O(8) atom to form distorted WO6 octahedra that share corners with two equivalent Sr(2)O6 pentagonal pyramids,  an edgeedge with one Sr(6)O6 octahedra, and  a faceface with one W(1)O6 octahedra. The W(4)-O(12) bond length is 2.19 Å. The W(4)-O(14) bond length is 2.03 Å. The W(4)-O(15) bond length is 1.90 Å. The W(4)-O(3) bond length is 2.09 Å. The W(4)-O(7) bond length is 1.83 Å. The W(4)-O(8) bond length is 1.86 Å. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(3), and one W(3) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Sr(1), one Sr(2), one Sr(5), and one W(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(3), one W(1), and one W(4) atom. In the fourth O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to one Sr(2), one Sr(5), and one W(2) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Sr(1), one W(2), and one W(3) atom. In the sixth O site, O(6) is bonded in a distorted see-saw-like geometry to one Sr(2), one Sr(5), one W(2), and one W(3) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Sr(2), one Sr(4), and one W(4) atom. In the eighth O site, O(8) is bonded in a distorted trigonal non-coplanar geometry to one Sr(3), one Sr(6), and one W(4) atom. In the ninth O site, O(9) is bonded to one Sr(3), one Sr(5), one Sr(6), and one W(1) atom to form distorted corner-sharing OSr3W tetrahedra. In the tenth O site, O(10) is bonded to one Sr(1), one Sr(2), one Sr(4), and one W(3) atom to form corner-sharing OSr3W tetrahedra. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Sr(6), one Mg(1), and one W(2) atom. In the twelfth O site, O(12) is bonded in a rectangular see-saw-like geometry to one Sr(5), one Sr(6), one W(1), and one W(4) atom. In the thirteenth O site, O(13) is bonded to one Sr(3), one Sr(4), one Mg(1), and one W(2) atom to form distorted corner-sharing OSr2MgW tetrahedra. In the fourteenth O site, O(14) is bonded in a 5-coordinate geometry to one Sr(2), one Sr(3), one Sr(4), one W(1), and one W(4) atom. In the fifteenth O site, O(15) is bonded in a 3-coordinate geometry to one Sr(5), one Mg(1), and one W(4) atom. In the sixteenth O site, O(16) is bonded in a rectangular see-saw-like geometry to one Sr(4), one Sr(6), one W(2), and one W(3) atom. In the seventeenth O site, O(17) is bonded in a distorted rectangular see-saw-like geometry to one Sr(4), one Sr(6), one Mg(1), and one W(3) atom. In the eighteenth O site, O(18) is bonded in a 3-coordinate geometry to one Sr(1), one Sr(4), and one W(1) atom.