Mn5(Si2O7)2 crystallizes in the triclinic P-1 space group. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a square co-planar geometry to two equivalent O(5) and two equivalent O(7) atoms. In the second Mn site, Mn(2) is bonded in a 4-coordinate geometry to one O(2), one O(4), and two equivalent O(1) atoms. In the third Mn site, Mn(3) is bonded to one O(4), one O(5), one O(7), and two equivalent O(6) atoms to form MnO5 trigonal bipyramids that share corners with two equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Mn(3)O5 trigonal bipyramid. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(4), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra and corners with two equivalent Mn(3)O5 trigonal bipyramids. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra and corners with three equivalent Mn(3)O5 trigonal bipyramids. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Mn(2) and one Si(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Mn(2) and one Si(2) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mn(2), one Mn(3), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(3), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to two equivalent Mn(3) and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(3), and one Si(1) atom.
Mn5(Si2O7)2 crystallizes in the triclinic P-1 space group. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a square co-planar geometry to two equivalent O(5) and two equivalent O(7) atoms. Both Mn(1)-O(5) bond lengths are 1.93 Å. Both Mn(1)-O(7) bond lengths are 1.94 Å. In the second Mn site, Mn(2) is bonded in a 4-coordinate geometry to one O(2), one O(4), and two equivalent O(1) atoms. The Mn(2)-O(2) bond length is 1.91 Å. The Mn(2)-O(4) bond length is 2.01 Å. There is one shorter (2.04 Å) and one longer (2.14 Å) Mn(2)-O(1) bond length. In the third Mn site, Mn(3) is bonded to one O(4), one O(5), one O(7), and two equivalent O(6) atoms to form MnO5 trigonal bipyramids that share corners with two equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Mn(3)O5 trigonal bipyramid. The Mn(3)-O(4) bond length is 2.12 Å. The Mn(3)-O(5) bond length is 2.16 Å. The Mn(3)-O(7) bond length is 2.21 Å. There is one shorter (2.12 Å) and one longer (2.15 Å) Mn(3)-O(6) bond length. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(4), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra and corners with two equivalent Mn(3)O5 trigonal bipyramids. The Si(1)-O(1) bond length is 1.65 Å. The Si(1)-O(3) bond length is 1.63 Å. The Si(1)-O(4) bond length is 1.63 Å. The Si(1)-O(7) bond length is 1.67 Å. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra and corners with three equivalent Mn(3)O5 trigonal bipyramids. The Si(2)-O(2) bond length is 1.61 Å. The Si(2)-O(3) bond length is 1.65 Å. The Si(2)-O(5) bond length is 1.67 Å. The Si(2)-O(6) bond length is 1.64 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Mn(2) and one Si(1) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Mn(2) and one Si(2) atom. In the third O site, O(3) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mn(2), one Mn(3), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(3), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to two equivalent Mn(3) and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(3), and one Si(1) atom.