Ba2MgNdBiO6 crystallizes in the triclinic P1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(5), and one O(6) atom. In the second Ba site, Ba(2) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(6) atom to form distorted BaO5 trigonal bipyramids that share corners with four equivalent Mg(1)O4 tetrahedra, corners with two equivalent Nd(1)O5 trigonal bipyramids, corners with three equivalent Bi(1)O4 trigonal pyramids, and  an edgeedge with one Nd(1)O5 trigonal bipyramid. Mg(1) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form distorted MgO4 tetrahedra that share  a cornercorner with one Nd(1)O5 trigonal bipyramid, corners with four equivalent Ba(2)O5 trigonal bipyramids, corners with two equivalent Bi(1)O4 trigonal pyramids, and  an edgeedge with one Nd(1)O5 trigonal bipyramid. Nd(1) is bonded to one O(1), one O(2), one O(4), one O(5), and one O(6) atom to form distorted NdO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O4 tetrahedra, corners with two equivalent Ba(2)O5 trigonal bipyramids, corners with three equivalent Bi(1)O4 trigonal pyramids,  an edgeedge with one Mg(1)O4 tetrahedra, and  an edgeedge with one Ba(2)O5 trigonal bipyramid. Bi(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form distorted BiO4 trigonal pyramids that share corners with two equivalent Mg(1)O4 tetrahedra, corners with three equivalent Ba(2)O5 trigonal bipyramids, and corners with three equivalent Nd(1)O5 trigonal bipyramids. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted see-saw-like geometry to one Ba(1), one Ba(2), one Mg(1), and one Nd(1) atom. In the second O site, O(2) is bonded to one Ba(1), one Ba(2), one Nd(1), and one Bi(1) atom to form distorted OBa2NdBi tetrahedra that share corners with three equivalent O(4)BaNdMgBi tetrahedra,  a cornercorner with one O(6)Ba2NdMg trigonal pyramid, and  an edgeedge with one O(6)Ba2NdMg trigonal pyramid. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one Mg(1), and one Bi(1) atom. In the fourth O site, O(4) is bonded to one Ba(2), one Mg(1), one Nd(1), and one Bi(1) atom to form distorted OBaNdMgBi tetrahedra that share corners with three equivalent O(2)Ba2NdBi tetrahedra,  a cornercorner with one O(6)Ba2NdMg trigonal pyramid, and  an edgeedge with one O(6)Ba2NdMg trigonal pyramid. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Ba(1), one Nd(1), and one Bi(1) atom. In the sixth O site, O(6) is bonded to one Ba(1), one Ba(2), one Mg(1), and one Nd(1) atom to form distorted OBa2NdMg trigonal pyramids that share  a cornercorner with one O(2)Ba2NdBi tetrahedra,  a cornercorner with one O(4)BaNdMgBi tetrahedra,  an edgeedge with one O(2)Ba2NdBi tetrahedra, and  an edgeedge with one O(4)BaNdMgBi tetrahedra.
Ba2MgNdBiO6 crystallizes in the triclinic P1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(5), and one O(6) atom. The Ba(1)-O(1) bond length is 2.66 Å. The Ba(1)-O(2) bond length is 2.67 Å. The Ba(1)-O(3) bond length is 3.01 Å. The Ba(1)-O(5) bond length is 2.76 Å. The Ba(1)-O(6) bond length is 2.57 Å. In the second Ba site, Ba(2) is bonded to one O(1), one O(2), one O(3), one O(4), and one O(6) atom to form distorted BaO5 trigonal bipyramids that share corners with four equivalent Mg(1)O4 tetrahedra, corners with two equivalent Nd(1)O5 trigonal bipyramids, corners with three equivalent Bi(1)O4 trigonal pyramids, and  an edgeedge with one Nd(1)O5 trigonal bipyramid. The Ba(2)-O(1) bond length is 2.53 Å. The Ba(2)-O(2) bond length is 2.76 Å. The Ba(2)-O(3) bond length is 2.69 Å. The Ba(2)-O(4) bond length is 2.68 Å. The Ba(2)-O(6) bond length is 2.67 Å. Mg(1) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form distorted MgO4 tetrahedra that share  a cornercorner with one Nd(1)O5 trigonal bipyramid, corners with four equivalent Ba(2)O5 trigonal bipyramids, corners with two equivalent Bi(1)O4 trigonal pyramids, and  an edgeedge with one Nd(1)O5 trigonal bipyramid. The Mg(1)-O(1) bond length is 2.01 Å. The Mg(1)-O(3) bond length is 2.02 Å. The Mg(1)-O(4) bond length is 1.99 Å. The Mg(1)-O(6) bond length is 1.99 Å. Nd(1) is bonded to one O(1), one O(2), one O(4), one O(5), and one O(6) atom to form distorted NdO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O4 tetrahedra, corners with two equivalent Ba(2)O5 trigonal bipyramids, corners with three equivalent Bi(1)O4 trigonal pyramids,  an edgeedge with one Mg(1)O4 tetrahedra, and  an edgeedge with one Ba(2)O5 trigonal bipyramid. The Nd(1)-O(1) bond length is 2.33 Å. The Nd(1)-O(2) bond length is 2.37 Å. The Nd(1)-O(4) bond length is 2.26 Å. The Nd(1)-O(5) bond length is 2.38 Å. The Nd(1)-O(6) bond length is 2.39 Å. Bi(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form distorted BiO4 trigonal pyramids that share corners with two equivalent Mg(1)O4 tetrahedra, corners with three equivalent Ba(2)O5 trigonal bipyramids, and corners with three equivalent Nd(1)O5 trigonal bipyramids. The Bi(1)-O(2) bond length is 2.16 Å. The Bi(1)-O(3) bond length is 2.24 Å. The Bi(1)-O(4) bond length is 2.62 Å. The Bi(1)-O(5) bond length is 2.14 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted see-saw-like geometry to one Ba(1), one Ba(2), one Mg(1), and one Nd(1) atom. In the second O site, O(2) is bonded to one Ba(1), one Ba(2), one Nd(1), and one Bi(1) atom to form distorted OBa2NdBi tetrahedra that share corners with three equivalent O(4)BaNdMgBi tetrahedra,  a cornercorner with one O(6)Ba2NdMg trigonal pyramid, and  an edgeedge with one O(6)Ba2NdMg trigonal pyramid. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one Mg(1), and one Bi(1) atom. In the fourth O site, O(4) is bonded to one Ba(2), one Mg(1), one Nd(1), and one Bi(1) atom to form distorted OBaNdMgBi tetrahedra that share corners with three equivalent O(2)Ba2NdBi tetrahedra,  a cornercorner with one O(6)Ba2NdMg trigonal pyramid, and  an edgeedge with one O(6)Ba2NdMg trigonal pyramid. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Ba(1), one Nd(1), and one Bi(1) atom. In the sixth O site, O(6) is bonded to one Ba(1), one Ba(2), one Mg(1), and one Nd(1) atom to form distorted OBa2NdMg trigonal pyramids that share  a cornercorner with one O(2)Ba2NdBi tetrahedra,  a cornercorner with one O(4)BaNdMgBi tetrahedra,  an edgeedge with one O(2)Ba2NdBi tetrahedra, and  an edgeedge with one O(4)BaNdMgBi tetrahedra.