LiMn2Si2O7 crystallizes in the monoclinic Cc space group. Li(1) is bonded to one O(2), one O(4), one O(5), and one O(7) atom to form distorted LiO4 trigonal pyramids that share  a cornercorner with one Si(2)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra, and corners with two equivalent Mn(1)O5 trigonal bipyramids. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(2), one O(3), one O(6), and one O(7) atom to form MnO5 trigonal bipyramids that share corners with three equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, and corners with two equivalent Li(1)O4 trigonal pyramids. In the second Mn site, Mn(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), one O(5), and one O(6) atom. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), one O(5), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra, corners with three equivalent Mn(1)O5 trigonal bipyramids, and corners with three equivalent Li(1)O4 trigonal pyramids. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra, corners with three equivalent Mn(1)O5 trigonal bipyramids, and  a cornercorner with one Li(1)O4 trigonal pyramid. There are seven inequivalent O sites. In the first O site, O(7) is bonded in a distorted trigonal planar geometry to one Li(1), one Mn(1), and one Si(1) atom. In the second O site, O(1) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one Si(2) atom. In the third O site, O(2) is bonded in a 4-coordinate geometry to one Li(1), one Mn(1), one Mn(2), and one Si(1) atom. In the fourth O site, O(3) is bonded in a distorted trigonal planar geometry to one Mn(1), one Si(1), and one Si(2) atom. In the fifth O site, O(4) is bonded in a distorted trigonal planar geometry to one Li(1), one Mn(2), and one Si(2) atom. In the sixth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Li(1), one Mn(2), and one Si(1) atom. In the seventh O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Mn(1), one Mn(2), and one Si(2) atom.
LiMn2Si2O7 crystallizes in the monoclinic Cc space group. Li(1) is bonded to one O(2), one O(4), one O(5), and one O(7) atom to form distorted LiO4 trigonal pyramids that share  a cornercorner with one Si(2)O4 tetrahedra, corners with three equivalent Si(1)O4 tetrahedra, and corners with two equivalent Mn(1)O5 trigonal bipyramids. The Li(1)-O(2) bond length is 2.04 Å. The Li(1)-O(4) bond length is 1.91 Å. The Li(1)-O(5) bond length is 2.07 Å. The Li(1)-O(7) bond length is 2.11 Å. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(1), one O(2), one O(3), one O(6), and one O(7) atom to form MnO5 trigonal bipyramids that share corners with three equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, and corners with two equivalent Li(1)O4 trigonal pyramids. The Mn(1)-O(1) bond length is 1.92 Å. The Mn(1)-O(2) bond length is 1.98 Å. The Mn(1)-O(3) bond length is 2.24 Å. The Mn(1)-O(6) bond length is 1.95 Å. The Mn(1)-O(7) bond length is 1.99 Å. In the second Mn site, Mn(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), one O(5), and one O(6) atom. The Mn(2)-O(1) bond length is 2.25 Å. The Mn(2)-O(2) bond length is 2.57 Å. The Mn(2)-O(4) bond length is 2.08 Å. The Mn(2)-O(5) bond length is 2.06 Å. The Mn(2)-O(6) bond length is 2.19 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), one O(5), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra, corners with three equivalent Mn(1)O5 trigonal bipyramids, and corners with three equivalent Li(1)O4 trigonal pyramids. The Si(1)-O(2) bond length is 1.66 Å. The Si(1)-O(3) bond length is 1.70 Å. The Si(1)-O(5) bond length is 1.60 Å. The Si(1)-O(7) bond length is 1.66 Å. In the second Si site, Si(2) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra, corners with three equivalent Mn(1)O5 trigonal bipyramids, and  a cornercorner with one Li(1)O4 trigonal pyramid. The Si(2)-O(1) bond length is 1.64 Å. The Si(2)-O(3) bond length is 1.69 Å. The Si(2)-O(4) bond length is 1.60 Å. The Si(2)-O(6) bond length is 1.65 Å. There are seven inequivalent O sites. In the first O site, O(7) is bonded in a distorted trigonal planar geometry to one Li(1), one Mn(1), and one Si(1) atom. In the second O site, O(1) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one Si(2) atom. In the third O site, O(2) is bonded in a 4-coordinate geometry to one Li(1), one Mn(1), one Mn(2), and one Si(1) atom. In the fourth O site, O(3) is bonded in a distorted trigonal planar geometry to one Mn(1), one Si(1), and one Si(2) atom. In the fifth O site, O(4) is bonded in a distorted trigonal planar geometry to one Li(1), one Mn(2), and one Si(2) atom. In the sixth O site, O(5) is bonded in a distorted trigonal non-coplanar geometry to one Li(1), one Mn(2), and one Si(1) atom. In the seventh O site, O(6) is bonded in a distorted trigonal non-coplanar geometry to one Mn(1), one Mn(2), and one Si(2) atom.