SrMgMn(PO4)2 crystallizes in the triclinic P-1 space group. Sr(1) is bonded in a 8-coordinate geometry to one O(2), one O(3), one O(4), one O(8), two equivalent O(1), and two equivalent O(6) atoms. Mg(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(4), one O(5), and one O(7) atom. Mn(1) is bonded to one O(3), one O(4), one O(5), one O(7), and two equivalent O(8) atoms to form distorted MnO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra,  an edgeedge with one Mn(1)O6 octahedra, and  an edgeedge with one P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(3), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-63°. In the second P site, P(2) is bonded to one O(4), one O(5), one O(6), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Mn(1)O6 octahedra and  an edgeedge with one Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-61°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to two equivalent Sr(1), one Mg(1), and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sr(1), one Mg(1), and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Sr(1), one Mn(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Sr(1), one Mg(1), one Mn(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Mg(1), one Mn(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to two equivalent Sr(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one Mn(1), and one P(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Sr(1), two equivalent Mn(1), and one P(2) atom.
SrMgMn(PO4)2 crystallizes in the triclinic P-1 space group. Sr(1) is bonded in a 8-coordinate geometry to one O(2), one O(3), one O(4), one O(8), two equivalent O(1), and two equivalent O(6) atoms. The Sr(1)-O(2) bond length is 2.73 Å. The Sr(1)-O(3) bond length is 2.57 Å. The Sr(1)-O(4) bond length is 2.81 Å. The Sr(1)-O(8) bond length is 2.96 Å. There is one shorter (2.58 Å) and one longer (2.68 Å) Sr(1)-O(1) bond length. There is one shorter (2.55 Å) and one longer (2.73 Å) Sr(1)-O(6) bond length. Mg(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(4), one O(5), and one O(7) atom. The Mg(1)-O(1) bond length is 2.58 Å. The Mg(1)-O(2) bond length is 2.00 Å. The Mg(1)-O(4) bond length is 2.03 Å. The Mg(1)-O(5) bond length is 2.04 Å. The Mg(1)-O(7) bond length is 2.03 Å. Mn(1) is bonded to one O(3), one O(4), one O(5), one O(7), and two equivalent O(8) atoms to form distorted MnO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra,  an edgeedge with one Mn(1)O6 octahedra, and  an edgeedge with one P(2)O4 tetrahedra. The Mn(1)-O(3) bond length is 2.15 Å. The Mn(1)-O(4) bond length is 2.28 Å. The Mn(1)-O(5) bond length is 2.28 Å. The Mn(1)-O(7) bond length is 2.08 Å. There is one shorter (2.21 Å) and one longer (2.27 Å) Mn(1)-O(8) bond length. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(3), and one O(7) atom to form PO4 tetrahedra that share corners with two equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-63°. The P(1)-O(1) bond length is 1.55 Å. The P(1)-O(2) bond length is 1.55 Å. The P(1)-O(3) bond length is 1.54 Å. The P(1)-O(7) bond length is 1.58 Å. In the second P site, P(2) is bonded to one O(4), one O(5), one O(6), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Mn(1)O6 octahedra and  an edgeedge with one Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 52-61°. The P(2)-O(4) bond length is 1.58 Å. The P(2)-O(5) bond length is 1.58 Å. The P(2)-O(6) bond length is 1.52 Å. The P(2)-O(8) bond length is 1.57 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to two equivalent Sr(1), one Mg(1), and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sr(1), one Mg(1), and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Sr(1), one Mn(1), and one P(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Sr(1), one Mg(1), one Mn(1), and one P(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Mg(1), one Mn(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to two equivalent Sr(1) and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Mg(1), one Mn(1), and one P(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Sr(1), two equivalent Mn(1), and one P(2) atom.