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 7-coordinate geometry to one O(6), two equivalent O(3), one Cl(2), and three 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 to one O(4), one O(7), two equivalent O(2), two equivalent O(5), two equivalent O(8), and four equivalent O(1) atoms to form BaO12 cuboctahedra that share corners with six equivalent Ba(4)O12 cuboctahedra, corners with three equivalent Nb(2)O6 octahedra, faces with three equivalent Nb(1)O6 octahedra, and faces with three equivalent Ir(1)O6 octahedra. The corner-sharing octahedral tilt angles are 16°. In the fifth Ba site, Ba(5) is bonded in a 9-coordinate geometry to one O(8), two equivalent O(1), two equivalent O(7), and four equivalent O(5) atoms. In the sixth Ba site, Ba(6) is bonded in a 10-coordinate geometry to one O(7), two equivalent O(5), two equivalent O(6), four equivalent O(3), and one Cl(1) atom. Mg(1) is bonded in a trigonal non-coplanar geometry to one O(6) and two equivalent O(3) 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 faces with three equivalent Ba(4)O12 cuboctahedra and  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 NbO6 octahedra that share corners with three equivalent Ba(4)O12 cuboctahedra and  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 faces with three equivalent Ba(4)O12 cuboctahedra,  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 to one Ba(2), one Ba(5), two equivalent Ba(4), one Nb(1), and one Ir(1) atom to form a mixture of distorted face and corner-sharing OBa4NbIr octahedra. The corner-sharing octahedral tilt angles range from 6-60°. In the second O site, O(2) 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 third O site, O(3) is bonded in a 2-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 6-coordinate geometry to one Ba(4), one Ba(6), two equivalent Ba(5), one Nb(2), and one Ir(1) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Ba(1), two equivalent Ba(6), one Mg(1), and one Nb(2) atom. In the seventh O site, O(7) is bonded in a 6-coordinate geometry to one Ba(4), 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 a mixture of distorted face and corner-sharing OBa4NbIr octahedra. The corner-sharing octahedral tilt angles range from 7-60°. There are two inequivalent Cl sites. In the first Cl site, Cl(1) is bonded to one Ba(3), one Ba(6), and three equivalent Ba(1) atoms to form distorted corner-sharing ClBa5 trigonal bipyramids. In the second Cl site, Cl(2) is bonded in a 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 7-coordinate geometry to one O(6), two equivalent O(3), one Cl(2), and three equivalent Cl(1) atoms. The Ba(1)-O(6) bond length is 2.74 Å. Both Ba(1)-O(3) bond lengths are 2.78 Å. The Ba(1)-Cl(2) bond length is 3.14 Å. There are two shorter (3.42 Å) and one longer (3.66 Å) Ba(1)-Cl(1) bond length. 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 2.71 Å. Both Ba(2)-O(1) bond lengths are 2.67 Å. Both Ba(2)-O(4) bond lengths are 3.05 Å. There are two shorter (3.03 Å) and two longer (3.04 Å) Ba(2)-O(2) bond lengths. The Ba(2)-Cl(2) bond length is 3.13 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 2.54 Å. Both Ba(3)-O(2) bond lengths are 2.60 Å. The Ba(3)-Cl(1) bond length is 3.60 Å. Both Ba(3)-Cl(2) bond lengths are 3.32 Å. In the fourth Ba site, Ba(4) is bonded to one O(4), one O(7), two equivalent O(2), two equivalent O(5), two equivalent O(8), and four equivalent O(1) atoms to form BaO12 cuboctahedra that share corners with six equivalent Ba(4)O12 cuboctahedra, corners with three equivalent Nb(2)O6 octahedra, faces with three equivalent Nb(1)O6 octahedra, and faces with three equivalent Ir(1)O6 octahedra. The corner-sharing octahedral tilt angles are 16°. The Ba(4)-O(4) bond length is 3.07 Å. The Ba(4)-O(7) bond length is 3.10 Å. Both Ba(4)-O(2) bond lengths are 3.02 Å. Both Ba(4)-O(5) bond lengths are 3.20 Å. Both Ba(4)-O(8) bond lengths are 3.01 Å. There are two shorter (2.97 Å) and two longer (3.02 Å) Ba(4)-O(1) bond lengths. In the fifth Ba site, Ba(5) is bonded in a 9-coordinate geometry to one O(8), two equivalent O(1), two equivalent O(7), and four equivalent O(5) atoms. The Ba(5)-O(8) bond length is 2.81 Å. Both Ba(5)-O(1) bond lengths are 2.85 Å. Both Ba(5)-O(7) bond lengths are 3.05 Å. There are two shorter (3.01 Å) and two longer (3.08 Å) Ba(5)-O(5) bond lengths. In the sixth Ba site, Ba(6) is bonded in a 10-coordinate geometry to one O(7), two equivalent O(5), two equivalent O(6), four equivalent O(3), and one Cl(1) atom. The Ba(6)-O(7) bond length is 2.68 Å. Both Ba(6)-O(5) bond lengths are 2.65 Å. Both Ba(6)-O(6) bond lengths are 3.06 Å. There are two shorter (3.01 Å) and two longer (3.07 Å) Ba(6)-O(3) bond lengths. The Ba(6)-Cl(1) bond length is 3.26 Å. Mg(1) is bonded in a trigonal non-coplanar geometry to one O(6) and two equivalent O(3) atoms. The Mg(1)-O(6) bond length is 1.97 Å. Both Mg(1)-O(3) bond lengths are 1.97 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 faces with three equivalent Ba(4)O12 cuboctahedra and  a faceface with one Ir(1)O6 octahedra. The Nb(1)-O(4) bond length is 1.90 Å. The Nb(1)-O(8) bond length is 2.21 Å. Both Nb(1)-O(1) bond lengths are 2.23 Å. Both Nb(1)-O(2) bond lengths are 1.90 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 NbO6 octahedra that share corners with three equivalent Ba(4)O12 cuboctahedra and  a faceface with one Ir(1)O6 octahedra. The Nb(2)-O(6) bond length is 2.02 Å. The Nb(2)-O(7) bond length is 2.09 Å. Both Nb(2)-O(3) bond lengths are 2.02 Å. Both Nb(2)-O(5) bond lengths are 2.08 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 faces with three equivalent Ba(4)O12 cuboctahedra,  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 2.10 Å. The Ir(1)-O(8) bond length is 2.07 Å. Both Ir(1)-O(1) bond lengths are 2.06 Å. Both Ir(1)-O(5) bond lengths are 2.10 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Ba(2), one Ba(5), two equivalent Ba(4), one Nb(1), and one Ir(1) atom to form a mixture of distorted face and corner-sharing OBa4NbIr octahedra. The corner-sharing octahedral tilt angles range from 6-60°. In the second O site, O(2) 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 third O site, O(3) is bonded in a 2-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 6-coordinate geometry to one Ba(4), one Ba(6), two equivalent Ba(5), one Nb(2), and one Ir(1) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Ba(1), two equivalent Ba(6), one Mg(1), and one Nb(2) atom. In the seventh O site, O(7) is bonded in a 6-coordinate geometry to one Ba(4), 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 a mixture of distorted face and corner-sharing OBa4NbIr octahedra. The corner-sharing octahedral tilt angles range from 7-60°. There are two inequivalent Cl sites. In the first Cl site, Cl(1) is bonded to one Ba(3), one Ba(6), and three equivalent Ba(1) atoms to form distorted corner-sharing ClBa5 trigonal bipyramids. In the second Cl site, Cl(2) is bonded in a see-saw-like geometry to one Ba(1), one Ba(2), and two equivalent Ba(3) atoms.