Sr2MgCuO3 crystallizes in the triclinic P1 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one O(2) and four equivalent O(3) atoms to form a mixture of corner and edge-sharing SrO5 square pyramids. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one O(3), two equivalent O(1), and four equivalent O(2) atoms. Mg(1) is bonded in a trigonal planar geometry to one O(3) and two equivalent O(1) atoms. Cu(1) is bonded in a distorted T-shaped geometry to one O(2) and two equivalent O(1) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted see-saw-like geometry to two equivalent Sr(2), two equivalent Mg(1), and two equivalent Cu(1) atoms. In the second O site, O(2) is bonded to one Sr(1), four equivalent Sr(2), and one Cu(1) atom to form OSr5Cu octahedra that share corners with four equivalent O(2)Sr5Cu octahedra, edges with four equivalent O(2)Sr5Cu octahedra, and edges with four equivalent O(3)Sr5Mg octahedra. The corner-sharing octahedral tilt angles are 14°. In the third O site, O(3) is bonded to one Sr(2), four equivalent Sr(1), and one Mg(1) atom to form distorted OSr5Mg octahedra that share corners with four equivalent O(3)Sr5Mg octahedra, edges with four equivalent O(2)Sr5Cu octahedra, and edges with four equivalent O(3)Sr5Mg octahedra. The corner-sharing octahedral tilt angles are 8°.
Sr2MgCuO3 crystallizes in the triclinic P1 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to one O(2) and four equivalent O(3) atoms to form a mixture of corner and edge-sharing SrO5 square pyramids. The Sr(1)-O(2) bond length is 2.38 Å. There are a spread of Sr(1)-O(3) bond distances ranging from 2.61-2.63 Å. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one O(3), two equivalent O(1), and four equivalent O(2) atoms. The Sr(2)-O(3) bond length is 2.89 Å. There is one shorter (2.80 Å) and one longer (2.89 Å) Sr(2)-O(1) bond length. There are a spread of Sr(2)-O(2) bond distances ranging from 2.62-2.64 Å. Mg(1) is bonded in a trigonal planar geometry to one O(3) and two equivalent O(1) atoms. The Mg(1)-O(3) bond length is 2.01 Å. Both Mg(1)-O(1) bond lengths are 2.04 Å. Cu(1) is bonded in a distorted T-shaped geometry to one O(2) and two equivalent O(1) atoms. The Cu(1)-O(2) bond length is 2.37 Å. There is one shorter (1.94 Å) and one longer (1.95 Å) Cu(1)-O(1) bond length. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted see-saw-like geometry to two equivalent Sr(2), two equivalent Mg(1), and two equivalent Cu(1) atoms. In the second O site, O(2) is bonded to one Sr(1), four equivalent Sr(2), and one Cu(1) atom to form OSr5Cu octahedra that share corners with four equivalent O(2)Sr5Cu octahedra, edges with four equivalent O(2)Sr5Cu octahedra, and edges with four equivalent O(3)Sr5Mg octahedra. The corner-sharing octahedral tilt angles are 14°. In the third O site, O(3) is bonded to one Sr(2), four equivalent Sr(1), and one Mg(1) atom to form distorted OSr5Mg octahedra that share corners with four equivalent O(3)Sr5Mg octahedra, edges with four equivalent O(2)Sr5Cu octahedra, and edges with four equivalent O(3)Sr5Mg octahedra. The corner-sharing octahedral tilt angles are 8°.