Li3BeCPO7 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(2), and two equivalent O(4) atoms to form LiO4 tetrahedra that share corners with two equivalent Be(1)O5 trigonal bipyramids and  an edgeedge with one P(1)O4 tetrahedra. In the second Li site, Li(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(6) atom. Be(1) is bonded to one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form distorted BeO5 trigonal bipyramids that share corners with two equivalent Li(1)O4 tetrahedra and corners with four equivalent P(1)O4 tetrahedra. C(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. P(1) is bonded to one O(5), one O(6), and two equivalent O(4) atoms to form PO4 tetrahedra that share corners with four equivalent Be(1)O5 trigonal bipyramids and  an edgeedge with one Li(1)O4 tetrahedra. 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 distorted OLi3C tetrahedra that share  a cornercorner with one O(3)Li2BeC tetrahedra, corners with four equivalent O(2)Li3C tetrahedra, and  an edgeedge with one O(3)Li2BeC tetrahedra. In the second O site, O(2) is bonded to one Li(1), two equivalent Li(2), and one C(1) atom to form distorted OLi3C tetrahedra that share corners with three equivalent O(3)Li2BeC tetrahedra and corners with four equivalent O(1)Li3C tetrahedra. In the third O site, O(3) is bonded to two equivalent Li(2), one Be(1), and one C(1) atom to form a mixture of distorted edge and corner-sharing OLi2BeC tetrahedra. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Li(1), one Li(2), one Be(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Be(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to two equivalent Li(2), one Be(1), and one P(1) atom.
Li3BeCPO7 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(2), and two equivalent O(4) atoms to form LiO4 tetrahedra that share corners with two equivalent Be(1)O5 trigonal bipyramids and  an edgeedge with one P(1)O4 tetrahedra. The Li(1)-O(1) bond length is 1.86 Å. The Li(1)-O(2) bond length is 1.92 Å. Both Li(1)-O(4) bond lengths are 2.03 Å. In the second Li site, Li(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(6) atom. The Li(2)-O(1) bond length is 2.20 Å. The Li(2)-O(2) bond length is 2.11 Å. The Li(2)-O(3) bond length is 2.22 Å. The Li(2)-O(4) bond length is 2.05 Å. The Li(2)-O(6) bond length is 2.00 Å. Be(1) is bonded to one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form distorted BeO5 trigonal bipyramids that share corners with two equivalent Li(1)O4 tetrahedra and corners with four equivalent P(1)O4 tetrahedra. The Be(1)-O(3) bond length is 1.77 Å. The Be(1)-O(5) bond length is 1.61 Å. The Be(1)-O(6) bond length is 1.69 Å. Both Be(1)-O(4) bond lengths are 1.92 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 1.29 Å. The C(1)-O(2) bond length is 1.30 Å. The C(1)-O(3) bond length is 1.29 Å. P(1) is bonded to one O(5), one O(6), and two equivalent O(4) atoms to form PO4 tetrahedra that share corners with four equivalent Be(1)O5 trigonal bipyramids and  an edgeedge with one Li(1)O4 tetrahedra. The P(1)-O(5) bond length is 1.54 Å. The P(1)-O(6) bond length is 1.53 Å. Both P(1)-O(4) bond lengths are 1.53 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 distorted OLi3C tetrahedra that share  a cornercorner with one O(3)Li2BeC tetrahedra, corners with four equivalent O(2)Li3C tetrahedra, and  an edgeedge with one O(3)Li2BeC tetrahedra. In the second O site, O(2) is bonded to one Li(1), two equivalent Li(2), and one C(1) atom to form distorted OLi3C tetrahedra that share corners with three equivalent O(3)Li2BeC tetrahedra and corners with four equivalent O(1)Li3C tetrahedra. In the third O site, O(3) is bonded to two equivalent Li(2), one Be(1), and one C(1) atom to form a mixture of distorted edge and corner-sharing OLi2BeC tetrahedra. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Li(1), one Li(2), one Be(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Be(1) and one P(1) atom. In the sixth O site, O(6) is bonded in a rectangular see-saw-like geometry to two equivalent Li(2), one Be(1), and one P(1) atom.