Sr2Mn2SeO4 crystallizes in the orthorhombic Pnma space group. Sr(1) is bonded in a 4-coordinate geometry to two equivalent Se(1), two equivalent O(1), and two equivalent O(2) atoms. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a distorted square co-planar geometry to one Se(1), two equivalent O(1), and two equivalent O(2) atoms. In the second Mn site, Mn(2) is bonded in a 4-coordinate geometry to one Se(1), two equivalent O(1), and two equivalent O(2) atoms. Se(1) is bonded in a 6-coordinate geometry to four equivalent Sr(1), one Mn(1), and one Mn(2) atom. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), one Mn(1), and one Mn(2) atom to form a mixture of distorted corner and edge-sharing OSr2Mn2 tetrahedra. In the second O site, O(2) is bonded to two equivalent Sr(1), one Mn(1), and one Mn(2) atom to form a mixture of corner and edge-sharing OSr2Mn2 tetrahedra.
Sr2Mn2SeO4 crystallizes in the orthorhombic Pnma space group. Sr(1) is bonded in a 4-coordinate geometry to two equivalent Se(1), two equivalent O(1), and two equivalent O(2) atoms. There is one shorter (3.35 Å) and one longer (3.38 Å) Sr(1)-Se(1) bond length. Both Sr(1)-O(1) bond lengths are 2.50 Å. There is one shorter (2.48 Å) and one longer (2.51 Å) Sr(1)-O(2) bond length. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a distorted square co-planar geometry to one Se(1), two equivalent O(1), and two equivalent O(2) atoms. The Mn(1)-Se(1) bond length is 3.03 Å. Both Mn(1)-O(1) bond lengths are 1.93 Å. Both Mn(1)-O(2) bond lengths are 1.94 Å. In the second Mn site, Mn(2) is bonded in a 4-coordinate geometry to one Se(1), two equivalent O(1), and two equivalent O(2) atoms. The Mn(2)-Se(1) bond length is 2.80 Å. Both Mn(2)-O(1) bond lengths are 1.95 Å. Both Mn(2)-O(2) bond lengths are 1.96 Å. Se(1) is bonded in a 6-coordinate geometry to four equivalent Sr(1), one Mn(1), and one Mn(2) atom. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), one Mn(1), and one Mn(2) atom to form a mixture of distorted corner and edge-sharing OSr2Mn2 tetrahedra. In the second O site, O(2) is bonded to two equivalent Sr(1), one Mn(1), and one Mn(2) atom to form a mixture of corner and edge-sharing OSr2Mn2 tetrahedra.