Li2CoSiO4 is beta beryllia-derived structured and crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form LiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Co(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Li(2)O4 tetrahedra. In the second Li site, Li(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form LiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with four equivalent Co(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Li(1)O4 tetrahedra. Co(1) is bonded to one O(2), one O(3), and two equivalent O(4) atoms to form distorted CoO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Co(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with four equivalent Li(2)O4 tetrahedra, and  an edgeedge with one Si(1)O4 tetrahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent Co(1)O4 tetrahedra, corners with four equivalent Li(1)O4 tetrahedra, corners with four equivalent Li(2)O4 tetrahedra, and  an edgeedge with one Co(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Li(2), two equivalent Li(1), and one Si(1) atom to form distorted OLi3Si trigonal pyramids that share corners with two equivalent O(3)Li2CoSi tetrahedra, corners with two equivalent O(4)LiCo2Si tetrahedra, corners with four equivalent O(2)Li2CoSi tetrahedra, corners with two equivalent O(1)Li3Si trigonal pyramids, and  an edgeedge with one O(3)Li2CoSi tetrahedra. In the second O site, O(2) is bonded to one Li(1), one Li(2), one Co(1), and one Si(1) atom to form distorted OLi2CoSi tetrahedra that share corners with two equivalent O(4)LiCo2Si tetrahedra, corners with four equivalent O(3)Li2CoSi tetrahedra, corners with four equivalent O(1)Li3Si trigonal pyramids, and  an edgeedge with one O(4)LiCo2Si tetrahedra. In the third O site, O(3) is bonded to one Li(1), one Li(2), one Co(1), and one Si(1) atom to form distorted OLi2CoSi tetrahedra that share corners with four equivalent O(2)Li2CoSi tetrahedra, corners with four equivalent O(4)LiCo2Si tetrahedra, corners with two equivalent O(1)Li3Si trigonal pyramids, and  an edgeedge with one O(1)Li3Si trigonal pyramid. In the fourth O site, O(4) is bonded to one Li(2), two equivalent Co(1), and one Si(1) atom to form distorted OLiCo2Si tetrahedra that share corners with two equivalent O(2)Li2CoSi tetrahedra, corners with two equivalent O(4)LiCo2Si tetrahedra, corners with four equivalent O(3)Li2CoSi tetrahedra, corners with two equivalent O(1)Li3Si trigonal pyramids, and  an edgeedge with one O(2)Li2CoSi tetrahedra.
Li2CoSiO4 is beta beryllia-derived structured and crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form LiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra, corners with two equivalent Co(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Li(2)O4 tetrahedra. The Li(1)-O(2) bond length is 1.97 Å. The Li(1)-O(3) bond length is 2.06 Å. There is one shorter (1.98 Å) and one longer (2.01 Å) Li(1)-O(1) bond length. In the second Li site, Li(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form LiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with four equivalent Co(1)O4 tetrahedra, corners with four equivalent Si(1)O4 tetrahedra, and  an edgeedge with one Li(1)O4 tetrahedra. The Li(2)-O(1) bond length is 2.02 Å. The Li(2)-O(2) bond length is 1.97 Å. The Li(2)-O(3) bond length is 2.00 Å. The Li(2)-O(4) bond length is 2.01 Å. Co(1) is bonded to one O(2), one O(3), and two equivalent O(4) atoms to form distorted CoO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Co(1)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, corners with four equivalent Li(2)O4 tetrahedra, and  an edgeedge with one Si(1)O4 tetrahedra. The Co(1)-O(2) bond length is 2.03 Å. The Co(1)-O(3) bond length is 1.95 Å. There is one shorter (1.97 Å) and one longer (2.08 Å) Co(1)-O(4) bond length. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent Co(1)O4 tetrahedra, corners with four equivalent Li(1)O4 tetrahedra, corners with four equivalent Li(2)O4 tetrahedra, and  an edgeedge with one Co(1)O4 tetrahedra. The Si(1)-O(1) bond length is 1.62 Å. The Si(1)-O(2) bond length is 1.66 Å. The Si(1)-O(3) bond length is 1.65 Å. The Si(1)-O(4) bond length is 1.70 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Li(2), two equivalent Li(1), and one Si(1) atom to form distorted OLi3Si trigonal pyramids that share corners with two equivalent O(3)Li2CoSi tetrahedra, corners with two equivalent O(4)LiCo2Si tetrahedra, corners with four equivalent O(2)Li2CoSi tetrahedra, corners with two equivalent O(1)Li3Si trigonal pyramids, and  an edgeedge with one O(3)Li2CoSi tetrahedra. In the second O site, O(2) is bonded to one Li(1), one Li(2), one Co(1), and one Si(1) atom to form distorted OLi2CoSi tetrahedra that share corners with two equivalent O(4)LiCo2Si tetrahedra, corners with four equivalent O(3)Li2CoSi tetrahedra, corners with four equivalent O(1)Li3Si trigonal pyramids, and  an edgeedge with one O(4)LiCo2Si tetrahedra. In the third O site, O(3) is bonded to one Li(1), one Li(2), one Co(1), and one Si(1) atom to form distorted OLi2CoSi tetrahedra that share corners with four equivalent O(2)Li2CoSi tetrahedra, corners with four equivalent O(4)LiCo2Si tetrahedra, corners with two equivalent O(1)Li3Si trigonal pyramids, and  an edgeedge with one O(1)Li3Si trigonal pyramid. In the fourth O site, O(4) is bonded to one Li(2), two equivalent Co(1), and one Si(1) atom to form distorted OLiCo2Si tetrahedra that share corners with two equivalent O(2)Li2CoSi tetrahedra, corners with two equivalent O(4)LiCo2Si tetrahedra, corners with four equivalent O(3)Li2CoSi tetrahedra, corners with two equivalent O(1)Li3Si trigonal pyramids, and  an edgeedge with one O(2)Li2CoSi tetrahedra.