Mn2P2O7 crystallizes in the monoclinic P2_1/c space group. Mn(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form distorted MnO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra and edges with three equivalent Mn(1)O6 octahedra. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with six equivalent Mn(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 39-62°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent P(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Mn(1) and one P(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Mn(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Mn(1) and one P(1) atom.
Mn2P2O7 crystallizes in the monoclinic P2_1/c space group. Mn(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form distorted MnO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra and edges with three equivalent Mn(1)O6 octahedra. There is one shorter (2.16 Å) and one longer (2.17 Å) Mn(1)-O(2) bond length. There is one shorter (2.11 Å) and one longer (2.31 Å) Mn(1)-O(3) bond length. There is one shorter (2.14 Å) and one longer (2.25 Å) Mn(1)-O(4) bond length. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with six equivalent Mn(1)O6 octahedra and  a cornercorner with one P(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 39-62°. The P(1)-O(1) bond length is 1.57 Å. The P(1)-O(2) bond length is 1.52 Å. The P(1)-O(3) bond length is 1.52 Å. The P(1)-O(4) bond length is 1.52 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent P(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Mn(1) and one P(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Mn(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Mn(1) and one P(1) atom.