MgTh4(B2O5)4 crystallizes in the monoclinic C2 space group. Mg(1) is bonded in a 4-coordinate geometry to two equivalent O(2) and two equivalent O(3) atoms. There are two inequivalent Th sites. In the first Th site, Th(1) is bonded to one O(7), one O(8), two equivalent O(10), two equivalent O(4), and two equivalent O(5) atoms to form distorted edge-sharing ThO8 hexagonal bipyramids. In the second Th site, Th(2) is bonded in a 8-coordinate geometry to one O(7), one O(8), two equivalent O(3), two equivalent O(6), and two equivalent O(9) atoms. There are four inequivalent B sites. In the first B site, B(1) is bonded in a trigonal planar geometry to one O(1), one O(8), and one O(9) atom. In the second B site, B(2) is bonded in a trigonal planar geometry to one O(1), one O(4), and one O(5) atom. In the third B site, B(3) is bonded in a trigonal planar geometry to one O(2), one O(3), and one O(6) atom. In the fourth B site, B(4) is bonded in a trigonal planar geometry to one O(10), one O(2), and one O(7) atom. There are ten inequivalent O sites. In the first O site, O(4) is bonded in a distorted single-bond geometry to two equivalent Th(1) and one B(2) atom. In the second O site, O(5) is bonded in a distorted single-bond geometry to two equivalent Th(1) and one B(2) atom. In the third O site, O(6) is bonded in a distorted single-bond geometry to two equivalent Th(2) and one B(3) atom. In the fourth O site, O(7) is bonded in a distorted single-bond geometry to one Th(1), one Th(2), and one B(4) atom. In the fifth O site, O(8) is bonded in a distorted single-bond geometry to one Th(1), one Th(2), and one B(1) atom. In the sixth O site, O(9) is bonded in a 1-coordinate geometry to two equivalent Th(2) and one B(1) atom. In the seventh O site, O(10) is bonded in a 1-coordinate geometry to two equivalent Th(1) and one B(4) atom. In the eighth O site, O(1) is bonded in a bent 150 degrees geometry to one B(1) and one B(2) atom. In the ninth O site, O(2) is bonded in a 3-coordinate geometry to one Mg(1), one B(3), and one B(4) atom. In the tenth O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent Th(2), and one B(3) atom.
MgTh4(B2O5)4 crystallizes in the monoclinic C2 space group. Mg(1) is bonded in a 4-coordinate geometry to two equivalent O(2) and two equivalent O(3) atoms. Both Mg(1)-O(2) bond lengths are 2.07 Å. Both Mg(1)-O(3) bond lengths are 2.17 Å. There are two inequivalent Th sites. In the first Th site, Th(1) is bonded to one O(7), one O(8), two equivalent O(10), two equivalent O(4), and two equivalent O(5) atoms to form distorted edge-sharing ThO8 hexagonal bipyramids. The Th(1)-O(7) bond length is 2.48 Å. The Th(1)-O(8) bond length is 2.36 Å. There is one shorter (2.35 Å) and one longer (2.66 Å) Th(1)-O(10) bond length. There is one shorter (2.44 Å) and one longer (2.46 Å) Th(1)-O(4) bond length. There is one shorter (2.44 Å) and one longer (2.56 Å) Th(1)-O(5) bond length. In the second Th site, Th(2) is bonded in a 8-coordinate geometry to one O(7), one O(8), two equivalent O(3), two equivalent O(6), and two equivalent O(9) atoms. The Th(2)-O(7) bond length is 2.45 Å. The Th(2)-O(8) bond length is 2.41 Å. There is one shorter (2.47 Å) and one longer (2.63 Å) Th(2)-O(3) bond length. There is one shorter (2.39 Å) and one longer (2.66 Å) Th(2)-O(6) bond length. There is one shorter (2.37 Å) and one longer (2.71 Å) Th(2)-O(9) bond length. There are four inequivalent B sites. In the first B site, B(1) is bonded in a trigonal planar geometry to one O(1), one O(8), and one O(9) atom. The B(1)-O(1) bond length is 1.38 Å. The B(1)-O(8) bond length is 1.40 Å. The B(1)-O(9) bond length is 1.38 Å. In the second B site, B(2) is bonded in a trigonal planar geometry to one O(1), one O(4), and one O(5) atom. The B(2)-O(1) bond length is 1.37 Å. The B(2)-O(4) bond length is 1.39 Å. The B(2)-O(5) bond length is 1.38 Å. In the third B site, B(3) is bonded in a trigonal planar geometry to one O(2), one O(3), and one O(6) atom. The B(3)-O(2) bond length is 1.41 Å. The B(3)-O(3) bond length is 1.38 Å. The B(3)-O(6) bond length is 1.35 Å. In the fourth B site, B(4) is bonded in a trigonal planar geometry to one O(10), one O(2), and one O(7) atom. The B(4)-O(10) bond length is 1.37 Å. The B(4)-O(2) bond length is 1.40 Å. The B(4)-O(7) bond length is 1.37 Å. There are ten inequivalent O sites. In the first O site, O(4) is bonded in a distorted single-bond geometry to two equivalent Th(1) and one B(2) atom. In the second O site, O(5) is bonded in a distorted single-bond geometry to two equivalent Th(1) and one B(2) atom. In the third O site, O(6) is bonded in a distorted single-bond geometry to two equivalent Th(2) and one B(3) atom. In the fourth O site, O(7) is bonded in a distorted single-bond geometry to one Th(1), one Th(2), and one B(4) atom. In the fifth O site, O(8) is bonded in a distorted single-bond geometry to one Th(1), one Th(2), and one B(1) atom. In the sixth O site, O(9) is bonded in a 1-coordinate geometry to two equivalent Th(2) and one B(1) atom. In the seventh O site, O(10) is bonded in a 1-coordinate geometry to two equivalent Th(1) and one B(4) atom. In the eighth O site, O(1) is bonded in a bent 150 degrees geometry to one B(1) and one B(2) atom. In the ninth O site, O(2) is bonded in a 3-coordinate geometry to one Mg(1), one B(3), and one B(4) atom. In the tenth O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent Th(2), and one B(3) atom.