Mg2Ta2WO8 crystallizes in the triclinic P1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 6-coordinate geometry to one O(12), one O(13), one O(14), one O(15), one O(16), and one O(9) atom. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one O(10), one O(11), one O(13), one O(14), one O(15), and one O(16) atom. In the third Mg site, Mg(3) is bonded to one O(10), one O(11), one O(12), one O(14), one O(16), and one O(9) atom to form distorted MgO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, corners with two equivalent Ta(4)O6 octahedra, and  a faceface with one Ta(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-58°. In the fourth Mg site, Mg(4) is bonded in a 6-coordinate geometry to one O(10), one O(11), one O(12), one O(13), one O(15), and one O(9) atom. There are four inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(1), one O(14), one O(15), one O(4), one O(5), and one O(9) atom to form distorted TaO6 octahedra that share corners with two equivalent Mg(3)O6 octahedra, corners with two equivalent W(1)O6 octahedra, corners with two equivalent W(2)O6 octahedra, and edges with two equivalent Ta(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-57°. In the second Ta site, Ta(2) is bonded to one O(10), one O(13), one O(16), one O(2), one O(3), and one O(6) atom to form distorted TaO6 octahedra that share corners with two equivalent Mg(3)O6 octahedra, corners with two equivalent W(1)O6 octahedra, corners with two equivalent W(2)O6 octahedra, and edges with two equivalent Ta(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-58°. In the third Ta site, Ta(3) is bonded to one O(10), one O(12), one O(16), one O(2), one O(3), and one O(7) atom to form distorted TaO6 octahedra that share corners with two equivalent W(1)O6 octahedra, corners with two equivalent W(2)O6 octahedra, edges with two equivalent Ta(2)O6 octahedra, and  a faceface with one Mg(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-60°. In the fourth Ta site, Ta(4) is bonded to one O(1), one O(11), one O(15), one O(4), one O(8), and one O(9) atom to form distorted TaO6 octahedra that share corners with two equivalent Mg(3)O6 octahedra, corners with two equivalent W(1)O6 octahedra, corners with two equivalent W(2)O6 octahedra, and edges with two equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-58°. There are two inequivalent W sites. In the first W site, W(1) is bonded to one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form WO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, corners with two equivalent Ta(4)O6 octahedra, and edges with two equivalent W(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-58°. In the second W site, W(2) is bonded to one O(1), one O(2), one O(5), one O(6), one O(7), and one O(8) atom to form WO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, corners with two equivalent Ta(4)O6 octahedra, and edges with two equivalent W(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-60°. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ta(1), one Ta(4), and one W(2) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Ta(2), one Ta(3), and one W(2) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Ta(2), one Ta(3), and one W(1) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Ta(1), one Ta(4), and one W(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Ta(1), one W(1), and one W(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Ta(2), one W(1), and one W(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Ta(3), one W(1), and one W(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Ta(4), one W(1), and one W(2) atom. In the ninth O site, O(9) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(3), one Mg(4), one Ta(1), and one Ta(4) atom. In the tenth O site, O(10) is bonded to one Mg(2), one Mg(3), one Mg(4), one Ta(2), and one Ta(3) atom to form a mixture of distorted corner and edge-sharing OMg3Ta2 trigonal bipyramids. In the eleventh O site, O(11) is bonded to one Mg(2), one Mg(3), one Mg(4), and one Ta(4) atom to form OMg3Ta trigonal pyramids that share  a cornercorner with one O(10)Mg3Ta2 trigonal bipyramid, corners with two equivalent O(12)Mg3Ta trigonal pyramids, corners with two equivalent O(14)Mg3Ta trigonal pyramids,  an edgeedge with one O(10)Mg3Ta2 trigonal bipyramid, and  an edgeedge with one O(13)Mg3Ta trigonal pyramid. In the twelfth O site, O(12) is bonded to one Mg(1), one Mg(3), one Mg(4), and one Ta(3) atom to form OMg3Ta trigonal pyramids that share  a cornercorner with one O(10)Mg3Ta2 trigonal bipyramid, corners with two equivalent O(11)Mg3Ta trigonal pyramids, corners with two equivalent O(13)Mg3Ta trigonal pyramids,  an edgeedge with one O(10)Mg3Ta2 trigonal bipyramid, and  an edgeedge with one O(14)Mg3Ta trigonal pyramid. In the thirteenth O site, O(13) is bonded to one Mg(1), one Mg(2), one Mg(4), and one Ta(2) atom to form OMg3Ta trigonal pyramids that share  a cornercorner with one O(10)Mg3Ta2 trigonal bipyramid, corners with two equivalent O(12)Mg3Ta trigonal pyramids, corners with two equivalent O(14)Mg3Ta trigonal pyramids,  an edgeedge with one O(10)Mg3Ta2 trigonal bipyramid, and  an edgeedge with one O(11)Mg3Ta trigonal pyramid. In the fourteenth O site, O(14) is bonded to one Mg(1), one Mg(2), one Mg(3), and one Ta(1) atom to form OMg3Ta trigonal pyramids that share corners with two equivalent O(11)Mg3Ta trigonal pyramids, corners with two equivalent O(13)Mg3Ta trigonal pyramids,  an edgeedge with one O(10)Mg3Ta2 trigonal bipyramid, and  an edgeedge with one O(12)Mg3Ta trigonal pyramid. In the fifteenth O site, O(15) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(2), one Mg(4), one Ta(1), and one Ta(4) atom. In the sixteenth O site, O(16) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(2), one Mg(3), one Ta(2), and one Ta(3) atom.
Mg2Ta2WO8 crystallizes in the triclinic P1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 6-coordinate geometry to one O(12), one O(13), one O(14), one O(15), one O(16), and one O(9) atom. The Mg(1)-O(12) bond length is 1.99 Å. The Mg(1)-O(13) bond length is 1.95 Å. The Mg(1)-O(14) bond length is 2.27 Å. The Mg(1)-O(15) bond length is 2.61 Å. The Mg(1)-O(16) bond length is 1.98 Å. The Mg(1)-O(9) bond length is 2.46 Å. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one O(10), one O(11), one O(13), one O(14), one O(15), and one O(16) atom. The Mg(2)-O(10) bond length is 2.20 Å. The Mg(2)-O(11) bond length is 2.05 Å. The Mg(2)-O(13) bond length is 2.04 Å. The Mg(2)-O(14) bond length is 2.02 Å. The Mg(2)-O(15) bond length is 2.07 Å. The Mg(2)-O(16) bond length is 2.52 Å. In the third Mg site, Mg(3) is bonded to one O(10), one O(11), one O(12), one O(14), one O(16), and one O(9) atom to form distorted MgO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, corners with two equivalent Ta(4)O6 octahedra, and  a faceface with one Ta(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-58°. The Mg(3)-O(10) bond length is 2.25 Å. The Mg(3)-O(11) bond length is 2.03 Å. The Mg(3)-O(12) bond length is 2.07 Å. The Mg(3)-O(14) bond length is 2.09 Å. The Mg(3)-O(16) bond length is 2.26 Å. The Mg(3)-O(9) bond length is 2.10 Å. In the fourth Mg site, Mg(4) is bonded in a 6-coordinate geometry to one O(10), one O(11), one O(12), one O(13), one O(15), and one O(9) atom. The Mg(4)-O(10) bond length is 2.01 Å. The Mg(4)-O(11) bond length is 2.22 Å. The Mg(4)-O(12) bond length is 1.98 Å. The Mg(4)-O(13) bond length is 1.96 Å. The Mg(4)-O(15) bond length is 2.50 Å. The Mg(4)-O(9) bond length is 2.59 Å. There are four inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(1), one O(14), one O(15), one O(4), one O(5), and one O(9) atom to form distorted TaO6 octahedra that share corners with two equivalent Mg(3)O6 octahedra, corners with two equivalent W(1)O6 octahedra, corners with two equivalent W(2)O6 octahedra, and edges with two equivalent Ta(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-57°. The Ta(1)-O(1) bond length is 2.01 Å. The Ta(1)-O(14) bond length is 1.92 Å. The Ta(1)-O(15) bond length is 2.21 Å. The Ta(1)-O(4) bond length is 2.09 Å. The Ta(1)-O(5) bond length is 1.90 Å. The Ta(1)-O(9) bond length is 2.03 Å. In the second Ta site, Ta(2) is bonded to one O(10), one O(13), one O(16), one O(2), one O(3), and one O(6) atom to form distorted TaO6 octahedra that share corners with two equivalent Mg(3)O6 octahedra, corners with two equivalent W(1)O6 octahedra, corners with two equivalent W(2)O6 octahedra, and edges with two equivalent Ta(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 33-58°. The Ta(2)-O(10) bond length is 2.10 Å. The Ta(2)-O(13) bond length is 2.09 Å. The Ta(2)-O(16) bond length is 2.11 Å. The Ta(2)-O(2) bond length is 2.17 Å. The Ta(2)-O(3) bond length is 2.08 Å. The Ta(2)-O(6) bond length is 1.94 Å. In the third Ta site, Ta(3) is bonded to one O(10), one O(12), one O(16), one O(2), one O(3), and one O(7) atom to form distorted TaO6 octahedra that share corners with two equivalent W(1)O6 octahedra, corners with two equivalent W(2)O6 octahedra, edges with two equivalent Ta(2)O6 octahedra, and  a faceface with one Mg(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-60°. The Ta(3)-O(10) bond length is 2.24 Å. The Ta(3)-O(12) bond length is 2.01 Å. The Ta(3)-O(16) bond length is 2.32 Å. The Ta(3)-O(2) bond length is 1.95 Å. The Ta(3)-O(3) bond length is 2.03 Å. The Ta(3)-O(7) bond length is 2.07 Å. In the fourth Ta site, Ta(4) is bonded to one O(1), one O(11), one O(15), one O(4), one O(8), and one O(9) atom to form distorted TaO6 octahedra that share corners with two equivalent Mg(3)O6 octahedra, corners with two equivalent W(1)O6 octahedra, corners with two equivalent W(2)O6 octahedra, and edges with two equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-58°. The Ta(4)-O(1) bond length is 2.08 Å. The Ta(4)-O(11) bond length is 1.93 Å. The Ta(4)-O(15) bond length is 2.02 Å. The Ta(4)-O(4) bond length is 1.99 Å. The Ta(4)-O(8) bond length is 1.89 Å. The Ta(4)-O(9) bond length is 2.29 Å. There are two inequivalent W sites. In the first W site, W(1) is bonded to one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form WO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, corners with two equivalent Ta(4)O6 octahedra, and edges with two equivalent W(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-58°. The W(1)-O(3) bond length is 2.08 Å. The W(1)-O(4) bond length is 2.20 Å. The W(1)-O(5) bond length is 2.22 Å. The W(1)-O(6) bond length is 2.16 Å. The W(1)-O(7) bond length is 2.13 Å. The W(1)-O(8) bond length is 2.22 Å. In the second W site, W(2) is bonded to one O(1), one O(2), one O(5), one O(6), one O(7), and one O(8) atom to form WO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, corners with two equivalent Ta(4)O6 octahedra, and edges with two equivalent W(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 43-60°. The W(2)-O(1) bond length is 2.27 Å. The W(2)-O(2) bond length is 2.17 Å. The W(2)-O(5) bond length is 2.19 Å. The W(2)-O(6) bond length is 2.15 Å. The W(2)-O(7) bond length is 2.16 Å. The W(2)-O(8) bond length is 2.21 Å. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ta(1), one Ta(4), and one W(2) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Ta(2), one Ta(3), and one W(2) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Ta(2), one Ta(3), and one W(1) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Ta(1), one Ta(4), and one W(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Ta(1), one W(1), and one W(2) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Ta(2), one W(1), and one W(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Ta(3), one W(1), and one W(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Ta(4), one W(1), and one W(2) atom. In the ninth O site, O(9) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(3), one Mg(4), one Ta(1), and one Ta(4) atom. In the tenth O site, O(10) is bonded to one Mg(2), one Mg(3), one Mg(4), one Ta(2), and one Ta(3) atom to form a mixture of distorted corner and edge-sharing OMg3Ta2 trigonal bipyramids. In the eleventh O site, O(11) is bonded to one Mg(2), one Mg(3), one Mg(4), and one Ta(4) atom to form OMg3Ta trigonal pyramids that share  a cornercorner with one O(10)Mg3Ta2 trigonal bipyramid, corners with two equivalent O(12)Mg3Ta trigonal pyramids, corners with two equivalent O(14)Mg3Ta trigonal pyramids,  an edgeedge with one O(10)Mg3Ta2 trigonal bipyramid, and  an edgeedge with one O(13)Mg3Ta trigonal pyramid. In the twelfth O site, O(12) is bonded to one Mg(1), one Mg(3), one Mg(4), and one Ta(3) atom to form OMg3Ta trigonal pyramids that share  a cornercorner with one O(10)Mg3Ta2 trigonal bipyramid, corners with two equivalent O(11)Mg3Ta trigonal pyramids, corners with two equivalent O(13)Mg3Ta trigonal pyramids,  an edgeedge with one O(10)Mg3Ta2 trigonal bipyramid, and  an edgeedge with one O(14)Mg3Ta trigonal pyramid. In the thirteenth O site, O(13) is bonded to one Mg(1), one Mg(2), one Mg(4), and one Ta(2) atom to form OMg3Ta trigonal pyramids that share  a cornercorner with one O(10)Mg3Ta2 trigonal bipyramid, corners with two equivalent O(12)Mg3Ta trigonal pyramids, corners with two equivalent O(14)Mg3Ta trigonal pyramids,  an edgeedge with one O(10)Mg3Ta2 trigonal bipyramid, and  an edgeedge with one O(11)Mg3Ta trigonal pyramid. In the fourteenth O site, O(14) is bonded to one Mg(1), one Mg(2), one Mg(3), and one Ta(1) atom to form OMg3Ta trigonal pyramids that share corners with two equivalent O(11)Mg3Ta trigonal pyramids, corners with two equivalent O(13)Mg3Ta trigonal pyramids,  an edgeedge with one O(10)Mg3Ta2 trigonal bipyramid, and  an edgeedge with one O(12)Mg3Ta trigonal pyramid. In the fifteenth O site, O(15) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(2), one Mg(4), one Ta(1), and one Ta(4) atom. In the sixteenth O site, O(16) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(2), one Mg(3), one Ta(2), and one Ta(3) atom.