Na3CuSiCO7 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms. In the second Na site, Na(2) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form distorted NaO7 pentagonal bipyramids that share  a cornercorner with one Cu(1)O6 octahedra, corners with two equivalent Na(2)O7 pentagonal bipyramids, corners with two equivalent Si(1)O4 tetrahedra,  an edgeedge with one Cu(1)O6 octahedra,  an edgeedge with one Na(2)O7 pentagonal bipyramid,  an edgeedge with one Si(1)O4 tetrahedra,  a faceface with one Cu(1)O6 octahedra, and  a faceface with one Na(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 61°. Cu(1) is bonded to one O(2), one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form distorted CuO6 octahedra that share corners with two equivalent Na(2)O7 pentagonal bipyramids, corners with four equivalent Si(1)O4 tetrahedra, edges with two equivalent Na(2)O7 pentagonal bipyramids, and faces with two equivalent Na(2)O7 pentagonal bipyramids. Si(1) is bonded to one O(5), one O(6), and two equivalent O(4) atoms to form SiO4 tetrahedra that share corners with four equivalent Cu(1)O6 octahedra, corners with four equivalent Na(2)O7 pentagonal bipyramids, and edges with two equivalent Na(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 43-52°. 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 in a 5-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and one C(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Na(1), two equivalent Na(2), one Cu(1), and one C(1) atom. In the third O site, O(3) is bonded in a distorted trigonal bipyramidal geometry to one Na(1), two equivalent Na(2), one Cu(1), and one C(1) atom. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Na(2), one Cu(1), and one Si(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent Na(2), one Cu(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na(2), one Cu(1), and one Si(1) atom.
Na3CuSiCO7 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), two equivalent O(1), and two equivalent O(4) atoms. The Na(1)-O(2) bond length is 2.40 Å. The Na(1)-O(3) bond length is 2.59 Å. There is one shorter (2.48 Å) and one longer (2.68 Å) Na(1)-O(1) bond length. Both Na(1)-O(4) bond lengths are 2.42 Å. In the second Na site, Na(2) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form distorted NaO7 pentagonal bipyramids that share  a cornercorner with one Cu(1)O6 octahedra, corners with two equivalent Na(2)O7 pentagonal bipyramids, corners with two equivalent Si(1)O4 tetrahedra,  an edgeedge with one Cu(1)O6 octahedra,  an edgeedge with one Na(2)O7 pentagonal bipyramid,  an edgeedge with one Si(1)O4 tetrahedra,  a faceface with one Cu(1)O6 octahedra, and  a faceface with one Na(2)O7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 61°. The Na(2)-O(1) bond length is 2.32 Å. The Na(2)-O(2) bond length is 2.66 Å. The Na(2)-O(3) bond length is 2.45 Å. The Na(2)-O(5) bond length is 2.46 Å. The Na(2)-O(6) bond length is 2.24 Å. There is one shorter (2.48 Å) and one longer (2.78 Å) Na(2)-O(4) bond length. Cu(1) is bonded to one O(2), one O(3), one O(5), one O(6), and two equivalent O(4) atoms to form distorted CuO6 octahedra that share corners with two equivalent Na(2)O7 pentagonal bipyramids, corners with four equivalent Si(1)O4 tetrahedra, edges with two equivalent Na(2)O7 pentagonal bipyramids, and faces with two equivalent Na(2)O7 pentagonal bipyramids. The Cu(1)-O(2) bond length is 2.21 Å. The Cu(1)-O(3) bond length is 2.36 Å. The Cu(1)-O(5) bond length is 1.97 Å. The Cu(1)-O(6) bond length is 1.97 Å. Both Cu(1)-O(4) bond lengths are 2.02 Å. Si(1) is bonded to one O(5), one O(6), and two equivalent O(4) atoms to form SiO4 tetrahedra that share corners with four equivalent Cu(1)O6 octahedra, corners with four equivalent Na(2)O7 pentagonal bipyramids, and edges with two equivalent Na(2)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles range from 43-52°. The Si(1)-O(5) bond length is 1.66 Å. The Si(1)-O(6) bond length is 1.63 Å. Both Si(1)-O(4) bond lengths are 1.65 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 1.30 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to two equivalent Na(1), two equivalent Na(2), and one C(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Na(1), two equivalent Na(2), one Cu(1), and one C(1) atom. In the third O site, O(3) is bonded in a distorted trigonal bipyramidal geometry to one Na(1), two equivalent Na(2), one Cu(1), and one C(1) atom. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Na(2), one Cu(1), and one Si(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent Na(2), one Cu(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na(2), one Cu(1), and one Si(1) atom.