Li2MnP2O7 crystallizes in the monoclinic C2/c space group. Li(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form LiO4 tetrahedra that share corners with four equivalent P(1)O4 tetrahedra and  an edgeedge with one Li(1)O4 tetrahedra. Mn(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. 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  a cornercorner with one P(1)O4 tetrahedra and corners with four equivalent Li(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Li(1), one Mn(1), and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Li(1), one Mn(1), and one P(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to two equivalent Li(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to two equivalent P(1) atoms.
Li2MnP2O7 crystallizes in the monoclinic C2/c space group. Li(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form LiO4 tetrahedra that share corners with four equivalent P(1)O4 tetrahedra and  an edgeedge with one Li(1)O4 tetrahedra. The Li(1)-O(1) bond length is 2.00 Å. The Li(1)-O(2) bond length is 2.01 Å. There is one shorter (1.93 Å) and one longer (1.97 Å) Li(1)-O(3) bond length. Mn(1) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(2) atoms. Both Mn(1)-O(1) bond lengths are 2.08 Å. Both Mn(1)-O(2) bond lengths are 2.08 Å. 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  a cornercorner with one P(1)O4 tetrahedra and corners with four equivalent Li(1)O4 tetrahedra. The P(1)-O(1) bond length is 1.54 Å. The P(1)-O(2) bond length is 1.54 Å. The P(1)-O(3) bond length is 1.51 Å. The P(1)-O(4) bond length is 1.66 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted T-shaped geometry to one Li(1), one Mn(1), and one P(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Li(1), one Mn(1), and one P(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to two equivalent Li(1) and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to two equivalent P(1) atoms.