Ba2Mg3F10 crystallizes in the monoclinic C2/m space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 12-coordinate geometry to one F(4), two equivalent F(1), two equivalent F(8), three equivalent F(5), and four equivalent F(2) atoms. In the second Ba site, Ba(2) is bonded to one F(5), one F(6), two equivalent F(1), two equivalent F(2), two equivalent F(4), two equivalent F(7), and two equivalent F(8) atoms to form distorted BaF12 cuboctahedra that share corners with four equivalent Ba(2)F12 cuboctahedra, corners with two equivalent Mg(1)F6 octahedra,  an edgeedge with one Ba(2)F12 cuboctahedra, edges with two equivalent Mg(3)F6 octahedra, faces with two equivalent Mg(1)F6 octahedra, and faces with three equivalent Mg(2)F6 octahedra. The corner-sharing octahedral tilt angles are 46°. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one F(3), one F(4), two equivalent F(2), and two equivalent F(7) atoms to form MgF6 octahedra that share corners with two equivalent Ba(2)F12 cuboctahedra,  a cornercorner with one Mg(2)F6 octahedra, corners with two equivalent Mg(3)F6 octahedra,  an edgeedge with one Mg(1)F6 octahedra, and faces with two equivalent Ba(2)F12 cuboctahedra. The corner-sharing octahedral tilt angles range from 7-49°. In the second Mg site, Mg(2) is bonded to one F(4), one F(5), two equivalent F(1), and two equivalent F(8) atoms to form MgF6 octahedra that share  a cornercorner with one Mg(1)F6 octahedra, corners with two equivalent Mg(2)F6 octahedra, corners with two equivalent Mg(3)F6 octahedra, and faces with three equivalent Ba(2)F12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-50°. In the third Mg site, Mg(3) is bonded to two equivalent F(1), two equivalent F(3), and two equivalent F(6) atoms to form MgF6 octahedra that share corners with two equivalent Mg(1)F6 octahedra, corners with two equivalent Mg(2)F6 octahedra, edges with two equivalent Ba(2)F12 cuboctahedra, and edges with two equivalent Mg(3)F6 octahedra. The corner-sharing octahedral tilt angles range from 49-50°. There are eight inequivalent F sites. In the first F site, F(5) is bonded in a distorted single-bond geometry to one Ba(2), three equivalent Ba(1), and one Mg(2) atom. In the second F site, F(6) is bonded in a distorted L-shaped geometry to one Ba(2) and two equivalent Mg(3) atoms. In the third F site, F(7) is bonded in a 4-coordinate geometry to two equivalent Ba(2) and two equivalent Mg(1) atoms. In the fourth F site, F(8) is bonded in a linear geometry to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Mg(2) atoms. In the fifth F site, F(1) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(2), one Mg(2), and one Mg(3) atom. In the sixth F site, F(2) is bonded in a 4-coordinate geometry to one Ba(2), two equivalent Ba(1), and one Mg(1) atom. In the seventh F site, F(3) is bonded in a distorted trigonal planar geometry to one Mg(1) and two equivalent Mg(3) atoms. In the eighth F site, F(4) is bonded in a distorted linear geometry to one Ba(1), two equivalent Ba(2), one Mg(1), and one Mg(2) atom.
Ba2Mg3F10 crystallizes in the monoclinic C2/m space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 12-coordinate geometry to one F(4), two equivalent F(1), two equivalent F(8), three equivalent F(5), and four equivalent F(2) atoms. The Ba(1)-F(4) bond length is 2.96 Å. Both Ba(1)-F(1) bond lengths are 2.80 Å. Both Ba(1)-F(8) bond lengths are 3.11 Å. There is one shorter (2.95 Å) and two longer (3.01 Å) Ba(1)-F(5) bond lengths. There are two shorter (2.61 Å) and two longer (2.80 Å) Ba(1)-F(2) bond lengths. In the second Ba site, Ba(2) is bonded to one F(5), one F(6), two equivalent F(1), two equivalent F(2), two equivalent F(4), two equivalent F(7), and two equivalent F(8) atoms to form distorted BaF12 cuboctahedra that share corners with four equivalent Ba(2)F12 cuboctahedra, corners with two equivalent Mg(1)F6 octahedra,  an edgeedge with one Ba(2)F12 cuboctahedra, edges with two equivalent Mg(3)F6 octahedra, faces with two equivalent Mg(1)F6 octahedra, and faces with three equivalent Mg(2)F6 octahedra. The corner-sharing octahedral tilt angles are 46°. The Ba(2)-F(5) bond length is 2.77 Å. The Ba(2)-F(6) bond length is 2.82 Å. Both Ba(2)-F(1) bond lengths are 2.82 Å. Both Ba(2)-F(2) bond lengths are 2.72 Å. Both Ba(2)-F(4) bond lengths are 2.99 Å. Both Ba(2)-F(7) bond lengths are 2.73 Å. Both Ba(2)-F(8) bond lengths are 3.03 Å. There are three inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one F(3), one F(4), two equivalent F(2), and two equivalent F(7) atoms to form MgF6 octahedra that share corners with two equivalent Ba(2)F12 cuboctahedra,  a cornercorner with one Mg(2)F6 octahedra, corners with two equivalent Mg(3)F6 octahedra,  an edgeedge with one Mg(1)F6 octahedra, and faces with two equivalent Ba(2)F12 cuboctahedra. The corner-sharing octahedral tilt angles range from 7-49°. The Mg(1)-F(3) bond length is 1.97 Å. The Mg(1)-F(4) bond length is 2.10 Å. Both Mg(1)-F(2) bond lengths are 1.93 Å. Both Mg(1)-F(7) bond lengths are 2.01 Å. In the second Mg site, Mg(2) is bonded to one F(4), one F(5), two equivalent F(1), and two equivalent F(8) atoms to form MgF6 octahedra that share  a cornercorner with one Mg(1)F6 octahedra, corners with two equivalent Mg(2)F6 octahedra, corners with two equivalent Mg(3)F6 octahedra, and faces with three equivalent Ba(2)F12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-50°. The Mg(2)-F(4) bond length is 1.96 Å. The Mg(2)-F(5) bond length is 1.94 Å. Both Mg(2)-F(1) bond lengths are 1.96 Å. Both Mg(2)-F(8) bond lengths are 2.04 Å. In the third Mg site, Mg(3) is bonded to two equivalent F(1), two equivalent F(3), and two equivalent F(6) atoms to form MgF6 octahedra that share corners with two equivalent Mg(1)F6 octahedra, corners with two equivalent Mg(2)F6 octahedra, edges with two equivalent Ba(2)F12 cuboctahedra, and edges with two equivalent Mg(3)F6 octahedra. The corner-sharing octahedral tilt angles range from 49-50°. Both Mg(3)-F(1) bond lengths are 1.98 Å. Both Mg(3)-F(3) bond lengths are 2.00 Å. Both Mg(3)-F(6) bond lengths are 1.97 Å. There are eight inequivalent F sites. In the first F site, F(5) is bonded in a distorted single-bond geometry to one Ba(2), three equivalent Ba(1), and one Mg(2) atom. In the second F site, F(6) is bonded in a distorted L-shaped geometry to one Ba(2) and two equivalent Mg(3) atoms. In the third F site, F(7) is bonded in a 4-coordinate geometry to two equivalent Ba(2) and two equivalent Mg(1) atoms. In the fourth F site, F(8) is bonded in a linear geometry to two equivalent Ba(1), two equivalent Ba(2), and two equivalent Mg(2) atoms. In the fifth F site, F(1) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(2), one Mg(2), and one Mg(3) atom. In the sixth F site, F(2) is bonded in a 4-coordinate geometry to one Ba(2), two equivalent Ba(1), and one Mg(1) atom. In the seventh F site, F(3) is bonded in a distorted trigonal planar geometry to one Mg(1) and two equivalent Mg(3) atoms. In the eighth F site, F(4) is bonded in a distorted linear geometry to one Ba(1), two equivalent Ba(2), one Mg(1), and one Mg(2) atom.