Ba6MgNb2Ir(O6Cl)2 crystallizes in the monoclinic Cm space group. There are six inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to one O(6), two equivalent O(3), one Cl(2), and two equivalent Cl(1) atoms. In the second Ba site, Ba(2) is bonded in a 10-coordinate geometry to one O(8), two equivalent O(1), two equivalent O(4), four equivalent O(2), and one Cl(2) atom. In the third Ba site, Ba(3) is bonded in a 6-coordinate geometry to one O(4), two equivalent O(2), one Cl(1), and two equivalent Cl(2) atoms. In the fourth Ba site, Ba(4) is bonded in a 11-coordinate geometry to one O(4), two equivalent O(2), two equivalent O(5), two equivalent O(8), and four equivalent O(1) atoms. In the fifth Ba site, Ba(5) is bonded in a 9-coordinate geometry to one Mg(1), one O(6), one O(8), two equivalent O(1), two equivalent O(5), and two equivalent O(7) atoms. In the sixth Ba site, Ba(6) is bonded in a 1-coordinate geometry to one O(7), four equivalent O(3), and one Cl(1) atom. Mg(1) is bonded in a distorted square co-planar geometry to one Ba(5), two equivalent O(3), and two equivalent O(5) atoms. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(4), one O(8), two equivalent O(1), and two equivalent O(2) atoms to form distorted NbO6 octahedra that share  a faceface with one Ir(1)O6 octahedra. In the second Nb site, Nb(2) is bonded to one O(6), one O(7), two equivalent O(3), and two equivalent O(5) atoms to form distorted NbO6 octahedra that share  a faceface with one Ir(1)O6 octahedra. Ir(1) is bonded to one O(7), one O(8), two equivalent O(1), and two equivalent O(5) atoms to form IrO6 octahedra that share  a faceface with one Nb(1)O6 octahedra and  a faceface with one Nb(2)O6 octahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Ba(2), one Ba(5), two equivalent Ba(4), 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(3), one Ba(4), two equivalent Ba(2), and one Nb(1) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Ba(1), two equivalent Ba(6), one Mg(1), and one Nb(2) atom. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Ba(3), one Ba(4), two equivalent Ba(2), and one Nb(1) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Ba(4), one Ba(5), one Mg(1), one Nb(2), and one Ir(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(5), and one Nb(2) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Ba(6), two equivalent Ba(5), one Nb(2), and one Ir(1) atom. In the eighth O site, O(8) is bonded to one Ba(2), one Ba(5), two equivalent Ba(4), one Nb(1), and one Ir(1) atom to form distorted corner-sharing OBa4NbIr octahedra. The corner-sharing octahedral tilt angles are 9°. There are two inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a distorted see-saw-like geometry to one Ba(3), one Ba(6), and two equivalent Ba(1) atoms. In the second Cl site, Cl(2) is bonded in a distorted see-saw-like geometry to one Ba(1), one Ba(2), and two equivalent Ba(3) atoms.
Ba6MgNb2Ir(O6Cl)2 crystallizes in the monoclinic Cm space group. There are six inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to one O(6), two equivalent O(3), one Cl(2), and two equivalent Cl(1) atoms. The Ba(1)-O(6) bond length is 2.96 Å. Both Ba(1)-O(3) bond lengths are 2.53 Å. The Ba(1)-Cl(2) bond length is 3.27 Å. Both Ba(1)-Cl(1) bond lengths are 3.42 Å. In the second Ba site, Ba(2) is bonded in a 10-coordinate geometry to one O(8), two equivalent O(1), two equivalent O(4), four equivalent O(2), and one Cl(2) atom. The Ba(2)-O(8) bond length is 2.63 Å. Both Ba(2)-O(1) bond lengths are 2.83 Å. Both Ba(2)-O(4) bond lengths are 2.98 Å. There are two shorter (2.86 Å) and two longer (3.37 Å) Ba(2)-O(2) bond lengths. The Ba(2)-Cl(2) bond length is 3.19 Å. In the third Ba site, Ba(3) is bonded in a 6-coordinate geometry to one O(4), two equivalent O(2), one Cl(1), and two equivalent Cl(2) atoms. The Ba(3)-O(4) bond length is 2.61 Å. Both Ba(3)-O(2) bond lengths are 2.55 Å. The Ba(3)-Cl(1) bond length is 3.19 Å. Both Ba(3)-Cl(2) bond lengths are 3.41 Å. In the fourth Ba site, Ba(4) is bonded in a 11-coordinate geometry to one O(4), two equivalent O(2), two equivalent O(5), two equivalent O(8), and four equivalent O(1) atoms. The Ba(4)-O(4) bond length is 2.91 Å. Both Ba(4)-O(2) bond lengths are 3.08 Å. Both Ba(4)-O(5) bond lengths are 2.95 Å. Both Ba(4)-O(8) bond lengths are 2.98 Å. There are two shorter (2.84 Å) and two longer (3.33 Å) Ba(4)-O(1) bond lengths. In the fifth Ba site, Ba(5) is bonded in a 9-coordinate geometry to one Mg(1), one O(6), one O(8), two equivalent O(1), two equivalent O(5), and two equivalent O(7) atoms. The Ba(5)-Mg(1) bond length is 3.04 Å. The Ba(5)-O(6) bond length is 2.95 Å. The Ba(5)-O(8) bond length is 2.68 Å. Both Ba(5)-O(1) bond lengths are 2.69 Å. Both Ba(5)-O(5) bond lengths are 2.85 Å. Both Ba(5)-O(7) bond lengths are 3.30 Å. In the sixth Ba site, Ba(6) is bonded in a 1-coordinate geometry to one O(7), four equivalent O(3), and one Cl(1) atom. The Ba(6)-O(7) bond length is 2.38 Å. There are two shorter (2.99 Å) and two longer (3.18 Å) Ba(6)-O(3) bond lengths. The Ba(6)-Cl(1) bond length is 3.09 Å. Mg(1) is bonded in a distorted square co-planar geometry to one Ba(5), two equivalent O(3), and two equivalent O(5) atoms. Both Mg(1)-O(3) bond lengths are 2.01 Å. Both Mg(1)-O(5) bond lengths are 2.07 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(4), one O(8), two equivalent O(1), and two equivalent O(2) atoms to form distorted NbO6 octahedra that share  a faceface with one Ir(1)O6 octahedra. The Nb(1)-O(4) bond length is 1.95 Å. The Nb(1)-O(8) bond length is 2.18 Å. Both Nb(1)-O(1) bond lengths are 2.20 Å. Both Nb(1)-O(2) bond lengths are 1.91 Å. In the second Nb site, Nb(2) is bonded to one O(6), one O(7), two equivalent O(3), and two equivalent O(5) atoms to form distorted NbO6 octahedra that share  a faceface with one Ir(1)O6 octahedra. The Nb(2)-O(6) bond length is 1.98 Å. The Nb(2)-O(7) bond length is 2.33 Å. Both Nb(2)-O(3) bond lengths are 2.05 Å. Both Nb(2)-O(5) bond lengths are 2.16 Å. Ir(1) is bonded to one O(7), one O(8), two equivalent O(1), and two equivalent O(5) atoms to form IrO6 octahedra that share  a faceface with one Nb(1)O6 octahedra and  a faceface with one Nb(2)O6 octahedra. The Ir(1)-O(7) bond length is 2.02 Å. The Ir(1)-O(8) bond length is 2.13 Å. Both Ir(1)-O(1) bond lengths are 2.09 Å. Both Ir(1)-O(5) bond lengths are 2.14 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Ba(2), one Ba(5), two equivalent Ba(4), 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(3), one Ba(4), two equivalent Ba(2), and one Nb(1) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Ba(1), two equivalent Ba(6), one Mg(1), and one Nb(2) atom. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Ba(3), one Ba(4), two equivalent Ba(2), and one Nb(1) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Ba(4), one Ba(5), one Mg(1), one Nb(2), and one Ir(1) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(5), and one Nb(2) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Ba(6), two equivalent Ba(5), one Nb(2), and one Ir(1) atom. In the eighth O site, O(8) is bonded to one Ba(2), one Ba(5), two equivalent Ba(4), one Nb(1), and one Ir(1) atom to form distorted corner-sharing OBa4NbIr octahedra. The corner-sharing octahedral tilt angles are 9°. There are two inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a distorted see-saw-like geometry to one Ba(3), one Ba(6), and two equivalent Ba(1) atoms. In the second Cl site, Cl(2) is bonded in a distorted see-saw-like geometry to one Ba(1), one Ba(2), and two equivalent Ba(3) atoms.