Li3MnSiCO7 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), and two equivalent O(6) atoms. In the second Li site, Li(2) is bonded in a 4-coordinate geometry to one O(1), one O(4), one O(5), and one O(6) atom. Mn(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(4), one O(5), and two equivalent O(6) atoms. Si(1) is bonded in a tetrahedral geometry to one O(4), one O(5), and two equivalent O(6) atoms. C(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Li(1), two equivalent Li(2), and one C(1) atom to form a mixture of corner and edge-sharing OLi3C tetrahedra. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Li(1), one Mn(1), and one C(1) atom. In the third O site, O(3) is bonded in a distorted water-like geometry to one Mn(1) and one C(1) atom. In the fourth O site, O(4) is bonded to two equivalent Li(2), one Mn(1), and one Si(1) atom to form OLi2MnSi tetrahedra that share corners with four equivalent O(5)Li2MnSi trigonal pyramids, corners with six equivalent O(6)Li2MnSi trigonal pyramids, and  an edgeedge with one O(1)Li3C tetrahedra. In the fifth O site, O(5) is bonded to two equivalent Li(2), one Mn(1), and one Si(1) atom to form distorted OLi2MnSi trigonal pyramids that share corners with two equivalent O(1)Li3C tetrahedra, corners with four equivalent O(4)Li2MnSi tetrahedra, corners with two equivalent O(6)Li2MnSi trigonal pyramids, and edges with two equivalent O(6)Li2MnSi trigonal pyramids. In the sixth O site, O(6) is bonded to one Li(1), one Li(2), one Mn(1), and one Si(1) atom to form distorted OLi2MnSi trigonal pyramids that share corners with two equivalent O(1)Li3C tetrahedra, corners with three equivalent O(4)Li2MnSi tetrahedra,  a cornercorner with one O(5)Li2MnSi trigonal pyramid,  a cornercorner with one O(6)Li2MnSi trigonal pyramid,  an edgeedge with one O(5)Li2MnSi trigonal pyramid, and  an edgeedge with one O(6)Li2MnSi trigonal pyramid.
Li3MnSiCO7 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded in a 4-coordinate geometry to one O(1), one O(2), and two equivalent O(6) atoms. The Li(1)-O(1) bond length is 2.01 Å. The Li(1)-O(2) bond length is 1.91 Å. Both Li(1)-O(6) bond lengths are 2.13 Å. In the second Li site, Li(2) is bonded in a 4-coordinate geometry to one O(1), one O(4), one O(5), and one O(6) atom. The Li(2)-O(1) bond length is 2.07 Å. The Li(2)-O(4) bond length is 2.09 Å. The Li(2)-O(5) bond length is 2.07 Å. The Li(2)-O(6) bond length is 2.11 Å. Mn(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(4), one O(5), and two equivalent O(6) atoms. The Mn(1)-O(2) bond length is 2.49 Å. The Mn(1)-O(3) bond length is 2.03 Å. The Mn(1)-O(4) bond length is 2.13 Å. The Mn(1)-O(5) bond length is 2.00 Å. Both Mn(1)-O(6) bond lengths are 1.93 Å. Si(1) is bonded in a tetrahedral geometry to one O(4), one O(5), and two equivalent O(6) atoms. The Si(1)-O(4) bond length is 1.64 Å. The Si(1)-O(5) bond length is 1.64 Å. Both Si(1)-O(6) bond lengths are 1.66 Å. C(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. The C(1)-O(1) bond length is 1.30 Å. The C(1)-O(2) bond length is 1.28 Å. The C(1)-O(3) bond length is 1.32 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded to one Li(1), two equivalent Li(2), and one C(1) atom to form a mixture of corner and edge-sharing OLi3C tetrahedra. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Li(1), one Mn(1), and one C(1) atom. In the third O site, O(3) is bonded in a distorted water-like geometry to one Mn(1) and one C(1) atom. In the fourth O site, O(4) is bonded to two equivalent Li(2), one Mn(1), and one Si(1) atom to form OLi2MnSi tetrahedra that share corners with four equivalent O(5)Li2MnSi trigonal pyramids, corners with six equivalent O(6)Li2MnSi trigonal pyramids, and  an edgeedge with one O(1)Li3C tetrahedra. In the fifth O site, O(5) is bonded to two equivalent Li(2), one Mn(1), and one Si(1) atom to form distorted OLi2MnSi trigonal pyramids that share corners with two equivalent O(1)Li3C tetrahedra, corners with four equivalent O(4)Li2MnSi tetrahedra, corners with two equivalent O(6)Li2MnSi trigonal pyramids, and edges with two equivalent O(6)Li2MnSi trigonal pyramids. In the sixth O site, O(6) is bonded to one Li(1), one Li(2), one Mn(1), and one Si(1) atom to form distorted OLi2MnSi trigonal pyramids that share corners with two equivalent O(1)Li3C tetrahedra, corners with three equivalent O(4)Li2MnSi tetrahedra,  a cornercorner with one O(5)Li2MnSi trigonal pyramid,  a cornercorner with one O(6)Li2MnSi trigonal pyramid,  an edgeedge with one O(5)Li2MnSi trigonal pyramid, and  an edgeedge with one O(6)Li2MnSi trigonal pyramid.