Ba6MgNb2Ir(O6Cl)2 crystallizes in the triclinic P-1 space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(4), and three equivalent Cl(1) atoms. In the second Ba site, Ba(2) is bonded in a 10-coordinate geometry to one O(1), one O(5), one O(6), two equivalent O(2), two equivalent O(3), two equivalent O(4), and one Cl(1) atom. In the third Ba site, Ba(3) is bonded in a 9-coordinate geometry to one Ir(1), one O(1), one O(2), one O(3), one O(4), one O(5), and three equivalent O(6) atoms. Mg(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(5) atoms. Nb(1) is bonded in an octahedral geometry to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. Ir(1) is bonded in a distorted square co-planar geometry to two equivalent Ba(3), two equivalent O(1), and two equivalent O(5) atoms. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Ba(2), one Ba(3), one Mg(1), one Nb(1), and one Ir(1) atom. In the second O site, O(2) is bonded in a 1-coordinate geometry to one Ba(1), one Ba(3), two equivalent Ba(2), and one Nb(1) atom. In the third O site, O(3) is bonded in a 1-coordinate geometry to one Ba(1), one Ba(3), two equivalent Ba(2), and one Nb(1) atom. In the fourth O site, O(4) is bonded to one Ba(1), one Ba(3), two equivalent Ba(2), and one Nb(1) atom to form distorted OBa4Nb trigonal bipyramids that share corners with two equivalent O(5)Ba2MgNbIr trigonal bipyramids, corners with two equivalent O(4)Ba4Nb trigonal bipyramids, and  an edgeedge with one O(5)Ba2MgNbIr trigonal bipyramid. In the fifth O site, O(5) is bonded to one Ba(2), one Ba(3), one Mg(1), one Nb(1), and one Ir(1) atom to form distorted OBa2MgNbIr trigonal bipyramids that share corners with two equivalent O(5)Ba2MgNbIr trigonal bipyramids, corners with two equivalent O(4)Ba4Nb trigonal bipyramids, and  an edgeedge with one O(4)Ba4Nb trigonal bipyramid. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Ba(2), three equivalent Ba(3), and one Nb(1) atom. Cl(1) is bonded in a distorted see-saw-like geometry to one Ba(2) and three equivalent Ba(1) atoms.
Ba6MgNb2Ir(O6Cl)2 crystallizes in the triclinic P-1 space group. There are three inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(4), and three equivalent Cl(1) atoms. The Ba(1)-O(2) bond length is 2.59 Å. The Ba(1)-O(3) bond length is 2.59 Å. The Ba(1)-O(4) bond length is 2.65 Å. There are a spread of Ba(1)-Cl(1) bond distances ranging from 3.21-3.40 Å. In the second Ba site, Ba(2) is bonded in a 10-coordinate geometry to one O(1), one O(5), one O(6), two equivalent O(2), two equivalent O(3), two equivalent O(4), and one Cl(1) atom. The Ba(2)-O(1) bond length is 2.79 Å. The Ba(2)-O(5) bond length is 2.76 Å. The Ba(2)-O(6) bond length is 2.73 Å. There is one shorter (2.91 Å) and one longer (3.42 Å) Ba(2)-O(2) bond length. There is one shorter (3.01 Å) and one longer (3.32 Å) Ba(2)-O(3) bond length. There is one shorter (2.96 Å) and one longer (3.00 Å) Ba(2)-O(4) bond length. The Ba(2)-Cl(1) bond length is 3.13 Å. In the third Ba site, Ba(3) is bonded in a 9-coordinate geometry to one Ir(1), one O(1), one O(2), one O(3), one O(4), one O(5), and three equivalent O(6) atoms. The Ba(3)-Ir(1) bond length is 3.04 Å. The Ba(3)-O(1) bond length is 2.83 Å. The Ba(3)-O(2) bond length is 2.81 Å. The Ba(3)-O(3) bond length is 2.86 Å. The Ba(3)-O(4) bond length is 2.78 Å. The Ba(3)-O(5) bond length is 2.80 Å. There are a spread of Ba(3)-O(6) bond distances ranging from 2.94-3.13 Å. Mg(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(5) atoms. Both Mg(1)-O(1) bond lengths are 2.00 Å. Both Mg(1)-O(5) bond lengths are 1.99 Å. Nb(1) is bonded in an octahedral geometry to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. The Nb(1)-O(1) bond length is 2.32 Å. The Nb(1)-O(2) bond length is 1.93 Å. The Nb(1)-O(3) bond length is 1.90 Å. The Nb(1)-O(4) bond length is 2.03 Å. The Nb(1)-O(5) bond length is 2.24 Å. The Nb(1)-O(6) bond length is 2.02 Å. Ir(1) is bonded in a distorted square co-planar geometry to two equivalent Ba(3), two equivalent O(1), and two equivalent O(5) atoms. Both Ir(1)-O(1) bond lengths are 2.00 Å. Both Ir(1)-O(5) bond lengths are 2.11 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Ba(2), one Ba(3), one Mg(1), one Nb(1), and one Ir(1) atom. In the second O site, O(2) is bonded in a 1-coordinate geometry to one Ba(1), one Ba(3), two equivalent Ba(2), and one Nb(1) atom. In the third O site, O(3) is bonded in a 1-coordinate geometry to one Ba(1), one Ba(3), two equivalent Ba(2), and one Nb(1) atom. In the fourth O site, O(4) is bonded to one Ba(1), one Ba(3), two equivalent Ba(2), and one Nb(1) atom to form distorted OBa4Nb trigonal bipyramids that share corners with two equivalent O(5)Ba2MgNbIr trigonal bipyramids, corners with two equivalent O(4)Ba4Nb trigonal bipyramids, and  an edgeedge with one O(5)Ba2MgNbIr trigonal bipyramid. In the fifth O site, O(5) is bonded to one Ba(2), one Ba(3), one Mg(1), one Nb(1), and one Ir(1) atom to form distorted OBa2MgNbIr trigonal bipyramids that share corners with two equivalent O(5)Ba2MgNbIr trigonal bipyramids, corners with two equivalent O(4)Ba4Nb trigonal bipyramids, and  an edgeedge with one O(4)Ba4Nb trigonal bipyramid. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Ba(2), three equivalent Ba(3), and one Nb(1) atom. Cl(1) is bonded in a distorted see-saw-like geometry to one Ba(2) and three equivalent Ba(1) atoms.