Li3Mn3O8 is Spinel-like structured and crystallizes in the trigonal R-3m space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1) and three equivalent O(2) atoms to form LiO4 tetrahedra that share corners with three equivalent Li(2)O6 octahedra and corners with nine equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-65°. In the second Li site, Li(2) is bonded to six equivalent O(2) atoms to form LiO6 octahedra that share corners with six equivalent Li(1)O4 tetrahedra and edges with six equivalent Mn(1)O6 octahedra. Mn(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form MnO6 octahedra that share corners with six equivalent Li(1)O4 tetrahedra, edges with two equivalent Li(2)O6 octahedra, and edges with four equivalent Mn(1)O6 octahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Li(1) and three equivalent Mn(1) atoms to form distorted OLiMn3 trigonal pyramids that share corners with three equivalent O(1)LiMn3 trigonal pyramids, corners with nine equivalent O(2)Li2Mn2 trigonal pyramids, and edges with three equivalent O(2)Li2Mn2 trigonal pyramids. In the second O site, O(2) is bonded to one Li(1), one Li(2), and two equivalent Mn(1) atoms to form distorted OLi2Mn2 trigonal pyramids that share corners with three equivalent O(1)LiMn3 trigonal pyramids, corners with nine equivalent O(2)Li2Mn2 trigonal pyramids,  an edgeedge with one O(1)LiMn3 trigonal pyramid, and edges with two equivalent O(2)Li2Mn2 trigonal pyramids.
Li3Mn3O8 is Spinel-like structured and crystallizes in the trigonal R-3m space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1) and three equivalent O(2) atoms to form LiO4 tetrahedra that share corners with three equivalent Li(2)O6 octahedra and corners with nine equivalent Mn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 57-65°. The Li(1)-O(1) bond length is 2.05 Å. All Li(1)-O(2) bond lengths are 1.96 Å. In the second Li site, Li(2) is bonded to six equivalent O(2) atoms to form LiO6 octahedra that share corners with six equivalent Li(1)O4 tetrahedra and edges with six equivalent Mn(1)O6 octahedra. All Li(2)-O(2) bond lengths are 2.08 Å. Mn(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form MnO6 octahedra that share corners with six equivalent Li(1)O4 tetrahedra, edges with two equivalent Li(2)O6 octahedra, and edges with four equivalent Mn(1)O6 octahedra. Both Mn(1)-O(1) bond lengths are 1.97 Å. All Mn(1)-O(2) bond lengths are 1.91 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Li(1) and three equivalent Mn(1) atoms to form distorted OLiMn3 trigonal pyramids that share corners with three equivalent O(1)LiMn3 trigonal pyramids, corners with nine equivalent O(2)Li2Mn2 trigonal pyramids, and edges with three equivalent O(2)Li2Mn2 trigonal pyramids. In the second O site, O(2) is bonded to one Li(1), one Li(2), and two equivalent Mn(1) atoms to form distorted OLi2Mn2 trigonal pyramids that share corners with three equivalent O(1)LiMn3 trigonal pyramids, corners with nine equivalent O(2)Li2Mn2 trigonal pyramids,  an edgeedge with one O(1)LiMn3 trigonal pyramid, and edges with two equivalent O(2)Li2Mn2 trigonal pyramids.