Li2Mn(SiO3)2 crystallizes in the monoclinic C2 space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded in a 4-coordinate geometry to one O(3), one O(4), one O(5), and one O(6) atom. In the second Li site, Li(2) is bonded in a 4-coordinate geometry to two equivalent O(2) and two equivalent O(3) atoms. In the third Li site, Li(3) is bonded in a distorted see-saw-like geometry to two equivalent O(1) 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(2), and two equivalent O(3) atoms to form MnO6 octahedra that share corners with two equivalent Si(2)O4 tetrahedra and corners with four equivalent Si(1)O4 tetrahedra. In the second Mn site, Mn(2) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(6) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form SiO4 tetrahedra that share corners with two equivalent Mn(1)O6 octahedra and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-60°. In the second Si site, Si(2) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Mn(1)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 53°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Li(3), one Mn(1), one Mn(2), and one Si(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Li(2), one Mn(1), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Li(1), one Li(2), one Mn(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a T-shaped geometry to one Li(1), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Li(1), one Si(1), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Li(1), one Li(3), one Mn(2), and one Si(2) atom.
Li2Mn(SiO3)2 crystallizes in the monoclinic C2 space group. There are three inequivalent Li sites. In the first Li site, Li(1) is bonded in a 4-coordinate geometry to one O(3), one O(4), one O(5), and one O(6) atom. The Li(1)-O(3) bond length is 2.08 Å. The Li(1)-O(4) bond length is 2.05 Å. The Li(1)-O(5) bond length is 2.18 Å. The Li(1)-O(6) bond length is 2.12 Å. In the second Li site, Li(2) is bonded in a 4-coordinate geometry to two equivalent O(2) and two equivalent O(3) atoms. Both Li(2)-O(2) bond lengths are 2.05 Å. Both Li(2)-O(3) bond lengths are 1.85 Å. In the third Li site, Li(3) is bonded in a distorted see-saw-like geometry to two equivalent O(1) and two equivalent O(6) atoms. Both Li(3)-O(1) bond lengths are 2.00 Å. Both Li(3)-O(6) bond lengths are 2.03 Å. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form MnO6 octahedra that share corners with two equivalent Si(2)O4 tetrahedra and corners with four equivalent Si(1)O4 tetrahedra. Both Mn(1)-O(1) bond lengths are 2.43 Å. Both Mn(1)-O(2) bond lengths are 2.29 Å. Both Mn(1)-O(3) bond lengths are 2.05 Å. In the second Mn site, Mn(2) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(6) atoms. Both Mn(2)-O(1) bond lengths are 2.09 Å. Both Mn(2)-O(6) bond lengths are 2.12 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form SiO4 tetrahedra that share corners with two equivalent Mn(1)O6 octahedra and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 30-60°. The Si(1)-O(1) bond length is 1.64 Å. The Si(1)-O(2) bond length is 1.62 Å. The Si(1)-O(4) bond length is 1.68 Å. The Si(1)-O(5) bond length is 1.67 Å. In the second Si site, Si(2) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Mn(1)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 53°. The Si(2)-O(3) bond length is 1.62 Å. The Si(2)-O(4) bond length is 1.66 Å. The Si(2)-O(5) bond length is 1.66 Å. The Si(2)-O(6) bond length is 1.61 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Li(3), one Mn(1), one Mn(2), and one Si(1) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Li(2), one Mn(1), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one Li(1), one Li(2), one Mn(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a T-shaped geometry to one Li(1), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Li(1), one Si(1), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Li(1), one Li(3), one Mn(2), and one Si(2) atom.