Na3CrCAsO7 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 corners with two equivalent Na(2)O7 pentagonal bipyramids, corners with two equivalent Cr(1)O5 square pyramids, corners with two equivalent As(1)O4 tetrahedra,  an edgeedge with one Na(2)O7 pentagonal bipyramid,  an edgeedge with one As(1)O4 tetrahedra,  a faceface with one Na(2)O7 pentagonal bipyramid, and  a faceface with one Cr(1)O5 square pyramid. Cr(1) is bonded to one O(2), one O(5), one O(6), and two equivalent O(4) atoms to form distorted CrO5 square pyramids that share corners with four equivalent Na(2)O7 pentagonal bipyramids, corners with four equivalent As(1)O4 tetrahedra, and faces with two equivalent Na(2)O7 pentagonal bipyramids. 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 Na(2)O7 pentagonal bipyramids, corners with four equivalent Cr(1)O5 square pyramids, and edges with two equivalent Na(2)O7 pentagonal bipyramids. 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 5-coordinate geometry to one Na(1), two equivalent Na(2), one Cr(1), and one C(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Na(2), 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 Cr(1), and one As(1) atom. In the fifth O site, O(5) is bonded in a distorted tetrahedral geometry to two equivalent Na(2), one Cr(1), and one As(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 Cr(1), and one As(1) atom.
Na3CrCAsO7 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 2.53 Å. The Na(1)-O(3) bond length is 2.37 Å. There is one shorter (2.46 Å) and one longer (2.89 Å) Na(1)-O(1) bond length. Both Na(1)-O(4) bond lengths are 2.51 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 corners with two equivalent Na(2)O7 pentagonal bipyramids, corners with two equivalent Cr(1)O5 square pyramids, corners with two equivalent As(1)O4 tetrahedra,  an edgeedge with one Na(2)O7 pentagonal bipyramid,  an edgeedge with one As(1)O4 tetrahedra,  a faceface with one Na(2)O7 pentagonal bipyramid, and  a faceface with one Cr(1)O5 square pyramid. The Na(2)-O(1) bond length is 2.31 Å. The Na(2)-O(2) bond length is 2.82 Å. The Na(2)-O(3) bond length is 2.53 Å. The Na(2)-O(5) bond length is 2.50 Å. The Na(2)-O(6) bond length is 2.30 Å. There is one shorter (2.63 Å) and one longer (2.87 Å) Na(2)-O(4) bond length. Cr(1) is bonded to one O(2), one O(5), one O(6), and two equivalent O(4) atoms to form distorted CrO5 square pyramids that share corners with four equivalent Na(2)O7 pentagonal bipyramids, corners with four equivalent As(1)O4 tetrahedra, and faces with two equivalent Na(2)O7 pentagonal bipyramids. The Cr(1)-O(2) bond length is 2.12 Å. The Cr(1)-O(5) bond length is 2.09 Å. The Cr(1)-O(6) bond length is 2.33 Å. Both Cr(1)-O(4) bond lengths are 2.11 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 1.30 Å. The C(1)-O(2) bond length is 1.32 Å. The C(1)-O(3) bond length is 1.29 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 Na(2)O7 pentagonal bipyramids, corners with four equivalent Cr(1)O5 square pyramids, and edges with two equivalent Na(2)O7 pentagonal bipyramids. The As(1)-O(5) bond length is 1.74 Å. The As(1)-O(6) bond length is 1.70 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 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 5-coordinate geometry to one Na(1), two equivalent Na(2), one Cr(1), and one C(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Na(2), 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 Cr(1), and one As(1) atom. In the fifth O site, O(5) is bonded in a distorted tetrahedral geometry to two equivalent Na(2), one Cr(1), and one As(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 Cr(1), and one As(1) atom.