Sr2MgHfCrO6 crystallizes in the triclinic P1 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 7-coordinate geometry to one O(1), one O(3), one O(4), one O(5), one O(6), and two equivalent O(2) atoms. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one O(2), one O(3), one O(4), one O(5), one O(6), and two equivalent O(1) atoms. Mg(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form MgO6 octahedra that share faces with two equivalent Hf(1)O6 octahedra. Hf(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form HfO6 octahedra that share faces with two equivalent Mg(1)O6 octahedra. Cr(1) is bonded in a square co-planar geometry to one O(3), one O(4), one O(5), and one O(6) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Sr(1), two equivalent Sr(2), one Mg(1), and one Hf(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sr(2), two equivalent Sr(1), one Mg(1), and one Hf(1) atom. In the third O site, O(3) is bonded to one Sr(1), one Sr(2), one Mg(1), one Hf(1), and one Cr(1) atom to form a mixture of distorted face, corner, and edge-sharing OSr2HfMgCr trigonal bipyramids. In the fourth O site, O(4) is bonded to one Sr(1), one Sr(2), one Mg(1), one Hf(1), and one Cr(1) atom to form a mixture of distorted face, corner, and edge-sharing OSr2HfMgCr trigonal bipyramids. In the fifth O site, O(5) is bonded to one Sr(1), one Sr(2), one Mg(1), one Hf(1), and one Cr(1) atom to form a mixture of distorted face, corner, and edge-sharing OSr2HfMgCr trigonal bipyramids. In the sixth O site, O(6) is bonded to one Sr(1), one Sr(2), one Mg(1), one Hf(1), and one Cr(1) atom to form a mixture of distorted face, corner, and edge-sharing OSr2HfMgCr trigonal bipyramids.
Sr2MgHfCrO6 crystallizes in the triclinic P1 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 7-coordinate geometry to one O(1), one O(3), one O(4), one O(5), one O(6), and two equivalent O(2) atoms. The Sr(1)-O(1) bond length is 2.43 Å. The Sr(1)-O(3) bond length is 2.75 Å. The Sr(1)-O(4) bond length is 2.57 Å. The Sr(1)-O(5) bond length is 2.73 Å. The Sr(1)-O(6) bond length is 2.53 Å. There is one shorter (2.99 Å) and one longer (3.18 Å) Sr(1)-O(2) bond length. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one O(2), one O(3), one O(4), one O(5), one O(6), and two equivalent O(1) atoms. The Sr(2)-O(2) bond length is 2.42 Å. The Sr(2)-O(3) bond length is 2.53 Å. The Sr(2)-O(4) bond length is 2.77 Å. The Sr(2)-O(5) bond length is 2.56 Å. The Sr(2)-O(6) bond length is 2.74 Å. There is one shorter (3.03 Å) and one longer (3.12 Å) Sr(2)-O(1) bond length. Mg(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form MgO6 octahedra that share faces with two equivalent Hf(1)O6 octahedra. The Mg(1)-O(1) bond length is 2.23 Å. The Mg(1)-O(2) bond length is 2.22 Å. The Mg(1)-O(3) bond length is 2.05 Å. The Mg(1)-O(4) bond length is 2.06 Å. The Mg(1)-O(5) bond length is 2.06 Å. The Mg(1)-O(6) bond length is 2.05 Å. Hf(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form HfO6 octahedra that share faces with two equivalent Mg(1)O6 octahedra. The Hf(1)-O(1) bond length is 2.03 Å. The Hf(1)-O(2) bond length is 2.03 Å. The Hf(1)-O(3) bond length is 2.15 Å. The Hf(1)-O(4) bond length is 2.14 Å. The Hf(1)-O(5) bond length is 2.14 Å. The Hf(1)-O(6) bond length is 2.15 Å. Cr(1) is bonded in a square co-planar geometry to one O(3), one O(4), one O(5), and one O(6) atom. The Cr(1)-O(3) bond length is 2.08 Å. The Cr(1)-O(4) bond length is 2.08 Å. The Cr(1)-O(5) bond length is 2.08 Å. The Cr(1)-O(6) bond length is 2.08 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Sr(1), two equivalent Sr(2), one Mg(1), and one Hf(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sr(2), two equivalent Sr(1), one Mg(1), and one Hf(1) atom. In the third O site, O(3) is bonded to one Sr(1), one Sr(2), one Mg(1), one Hf(1), and one Cr(1) atom to form a mixture of distorted face, corner, and edge-sharing OSr2HfMgCr trigonal bipyramids. In the fourth O site, O(4) is bonded to one Sr(1), one Sr(2), one Mg(1), one Hf(1), and one Cr(1) atom to form a mixture of distorted face, corner, and edge-sharing OSr2HfMgCr trigonal bipyramids. In the fifth O site, O(5) is bonded to one Sr(1), one Sr(2), one Mg(1), one Hf(1), and one Cr(1) atom to form a mixture of distorted face, corner, and edge-sharing OSr2HfMgCr trigonal bipyramids. In the sixth O site, O(6) is bonded to one Sr(1), one Sr(2), one Mg(1), one Hf(1), and one Cr(1) atom to form a mixture of distorted face, corner, and edge-sharing OSr2HfMgCr trigonal bipyramids.