Sr2MgCu(OBr)2 crystallizes in the triclinic P1 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form distorted corner-sharing SrO4 tetrahedra. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to two equivalent O(2), one Br(2), and four equivalent Br(1) atoms. Mg(1) is bonded in a 3-coordinate geometry to one O(1) and two equivalent Br(2) atoms. Cu(1) is bonded in a linear geometry to two equivalent O(1) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), one Mg(1), and two equivalent Cu(1) atoms to form corner-sharing OSr2MgCu2 trigonal bipyramids. In the second O site, O(2) is bonded in a square co-planar geometry to two equivalent Sr(1) and two equivalent Sr(2) atoms. There are two inequivalent Br sites. In the first Br site, Br(1) is bonded in a 4-coordinate geometry to four equivalent Sr(2) atoms. In the second Br site, Br(2) is bonded in a 3-coordinate geometry to one Sr(2) and two equivalent Mg(1) atoms.
Sr2MgCu(OBr)2 crystallizes in the triclinic P1 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form distorted corner-sharing SrO4 tetrahedra. There is one shorter (2.64 Å) and one longer (2.70 Å) Sr(1)-O(1) bond length. There is one shorter (2.45 Å) and one longer (2.46 Å) Sr(1)-O(2) bond length. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to two equivalent O(2), one Br(2), and four equivalent Br(1) atoms. There is one shorter (2.53 Å) and one longer (2.57 Å) Sr(2)-O(2) bond length. The Sr(2)-Br(2) bond length is 3.46 Å. There are three shorter (3.19 Å) and one longer (3.20 Å) Sr(2)-Br(1) bond length. Mg(1) is bonded in a 3-coordinate geometry to one O(1) and two equivalent Br(2) atoms. The Mg(1)-O(1) bond length is 2.02 Å. Both Mg(1)-Br(2) bond lengths are 2.61 Å. Cu(1) is bonded in a linear geometry to two equivalent O(1) atoms. There is one shorter (1.87 Å) and one longer (1.88 Å) Cu(1)-O(1) bond length. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), one Mg(1), and two equivalent Cu(1) atoms to form corner-sharing OSr2MgCu2 trigonal bipyramids. In the second O site, O(2) is bonded in a square co-planar geometry to two equivalent Sr(1) and two equivalent Sr(2) atoms. There are two inequivalent Br sites. In the first Br site, Br(1) is bonded in a 4-coordinate geometry to four equivalent Sr(2) atoms. In the second Br site, Br(2) is bonded in a 3-coordinate geometry to one Sr(2) and two equivalent Mg(1) atoms.