Na3SnCAsO7 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 in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. Sn(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 SnO6 octahedra that share corners with four equivalent As(1)O4 tetrahedra. C(1) is bonded in a trigonal planar geometry to one O(1), one O(2), and one O(3) atom. As(1) is bonded to one O(5), one O(6), and two equivalent O(4) atoms to form AsO4 tetrahedra that share corners with four equivalent Sn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-71°. There are six inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Na(1), two equivalent Na(2), and one C(1) atom to form distorted ONa4C trigonal bipyramids that share corners with two equivalent O(1)Na4C trigonal bipyramids and  an edgeedge with one O(5)Na2SnAs tetrahedra. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Na(2), one Sn(1), and one C(1) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Na(2), one Sn(1), and one C(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Sn(1), and one As(1) atom. In the fifth O site, O(5) is bonded to two equivalent Na(2), one Sn(1), and one As(1) atom to form edge-sharing ONa2SnAs tetrahedra. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na(2), one Sn(1), and one As(1) atom.
Na3SnCAsO7 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 2.46 Å. The Na(1)-O(3) bond length is 2.42 Å. There is one shorter (2.64 Å) and one longer (2.71 Å) Na(1)-O(1) bond length. Both Na(1)-O(4) bond lengths are 2.57 Å. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. The Na(2)-O(1) bond length is 2.41 Å. The Na(2)-O(2) bond length is 2.79 Å. The Na(2)-O(3) bond length is 2.76 Å. The Na(2)-O(4) bond length is 2.42 Å. The Na(2)-O(5) bond length is 2.38 Å. The Na(2)-O(6) bond length is 2.57 Å. Sn(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 SnO6 octahedra that share corners with four equivalent As(1)O4 tetrahedra. The Sn(1)-O(2) bond length is 2.51 Å. The Sn(1)-O(3) bond length is 2.62 Å. The Sn(1)-O(5) bond length is 2.54 Å. The Sn(1)-O(6) bond length is 2.37 Å. Both Sn(1)-O(4) bond lengths are 2.43 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 1.32 Å. The C(1)-O(3) bond length is 1.31 Å. As(1) is bonded to one O(5), one O(6), and two equivalent O(4) atoms to form AsO4 tetrahedra that share corners with four equivalent Sn(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 51-71°. The As(1)-O(5) bond length is 1.72 Å. The As(1)-O(6) bond length is 1.75 Å. Both As(1)-O(4) bond lengths are 1.73 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Na(1), two equivalent Na(2), and one C(1) atom to form distorted ONa4C trigonal bipyramids that share corners with two equivalent O(1)Na4C trigonal bipyramids and  an edgeedge with one O(5)Na2SnAs tetrahedra. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Na(2), one Sn(1), and one C(1) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Na(2), one Sn(1), and one C(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Sn(1), and one As(1) atom. In the fifth O site, O(5) is bonded to two equivalent Na(2), one Sn(1), and one As(1) atom to form edge-sharing ONa2SnAs tetrahedra. In the sixth O site, O(6) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na(2), one Sn(1), and one As(1) atom.