SrMn2(SiO5)2 crystallizes in the monoclinic P2_1/m space group. Sr(1) is bonded in a 10-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form MnO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra and edges with two equivalent Mn(2)O6 octahedra. In the second Mn site, Mn(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form MnO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra and edges with two equivalent Mn(1)O6 octahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form SiO4 tetrahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with two equivalent Mn(2)O6 octahedra, and  a cornercorner with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-59°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Sr(1), one Mn(1), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Sr(1), one Mn(2), and one Si(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Sr(1), one Mn(1), one Mn(2), and one Si(1) atom. In the fourth O site, O(4) is bonded in a water-like geometry to one Mn(1) and one Mn(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to two equivalent Sr(1) and two equivalent Si(1) atoms. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to two equivalent Sr(1) atoms.
SrMn2(SiO5)2 crystallizes in the monoclinic P2_1/m space group. Sr(1) is bonded in a 10-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), two equivalent O(5), and two equivalent O(6) atoms. Both Sr(1)-O(1) bond lengths are 2.53 Å. Both Sr(1)-O(2) bond lengths are 2.48 Å. Both Sr(1)-O(3) bond lengths are 2.97 Å. There is one shorter (2.83 Å) and one longer (3.10 Å) Sr(1)-O(5) bond length. There is one shorter (2.70 Å) and one longer (2.85 Å) Sr(1)-O(6) bond length. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form MnO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra and edges with two equivalent Mn(2)O6 octahedra. Both Mn(1)-O(1) bond lengths are 1.91 Å. Both Mn(1)-O(3) bond lengths are 1.96 Å. Both Mn(1)-O(4) bond lengths are 1.82 Å. In the second Mn site, Mn(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form MnO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra and edges with two equivalent Mn(1)O6 octahedra. Both Mn(2)-O(2) bond lengths are 1.88 Å. Both Mn(2)-O(3) bond lengths are 1.98 Å. Both Mn(2)-O(4) bond lengths are 1.82 Å. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(5) atom to form SiO4 tetrahedra that share corners with two equivalent Mn(1)O6 octahedra, corners with two equivalent Mn(2)O6 octahedra, and  a cornercorner with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-59°. The Si(1)-O(1) bond length is 1.60 Å. The Si(1)-O(2) bond length is 1.60 Å. The Si(1)-O(3) bond length is 1.67 Å. The Si(1)-O(5) bond length is 1.64 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Sr(1), one Mn(1), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Sr(1), one Mn(2), and one Si(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Sr(1), one Mn(1), one Mn(2), and one Si(1) atom. In the fourth O site, O(4) is bonded in a water-like geometry to one Mn(1) and one Mn(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to two equivalent Sr(1) and two equivalent Si(1) atoms. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to two equivalent Sr(1) atoms.