Na4Bi2As(CO4)4 crystallizes in the orthorhombic Fddd space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted NaO6 octahedra that share corners with four equivalent Na(2)O6 octahedra, edges with two equivalent Bi(1)O6 octahedra, and  an edgeedge with one As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 56-83°. In the second Na site, Na(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form distorted NaO6 octahedra that share corners with four equivalent Na(1)O6 octahedra, edges with two equivalent Bi(1)O6 octahedra, and  an edgeedge with one As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 56-83°. C(1) is bonded in a trigonal planar geometry to one O(1), one O(3), and one O(4) atom. Bi(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form BiO6 octahedra that share edges with two equivalent Na(1)O6 octahedra and edges with two equivalent Na(2)O6 octahedra. As(1) is bonded to four equivalent O(2) atoms to form AsO4 tetrahedra that share edges with two equivalent Na(1)O6 octahedra and edges with two equivalent Na(2)O6 octahedra. There are four inequivalent O sites. In the first O site, O(2) is bonded in a distorted T-shaped geometry to one Na(1), one Na(2), and one As(1) atom. In the second O site, O(3) is bonded in a 3-coordinate geometry to one Na(2), one C(1), and one Bi(1) atom. In the third O site, O(1) is bonded in a distorted single-bond geometry to one Na(1), one C(1), and one Bi(1) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(2), one C(1), and one Bi(1) atom.
Na4Bi2As(CO4)4 crystallizes in the orthorhombic Fddd space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted NaO6 octahedra that share corners with four equivalent Na(2)O6 octahedra, edges with two equivalent Bi(1)O6 octahedra, and  an edgeedge with one As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 56-83°. Both Na(1)-O(1) bond lengths are 2.59 Å. Both Na(1)-O(2) bond lengths are 2.39 Å. Both Na(1)-O(4) bond lengths are 2.59 Å. In the second Na site, Na(2) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form distorted NaO6 octahedra that share corners with four equivalent Na(1)O6 octahedra, edges with two equivalent Bi(1)O6 octahedra, and  an edgeedge with one As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 56-83°. Both Na(2)-O(2) bond lengths are 2.39 Å. Both Na(2)-O(3) bond lengths are 2.52 Å. Both Na(2)-O(4) bond lengths are 2.74 Å. C(1) is bonded in a trigonal planar geometry to one O(1), one O(3), and one O(4) atom. The C(1)-O(1) bond length is 1.30 Å. The C(1)-O(3) bond length is 1.30 Å. The C(1)-O(4) bond length is 1.31 Å. Bi(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form BiO6 octahedra that share edges with two equivalent Na(1)O6 octahedra and edges with two equivalent Na(2)O6 octahedra. Both Bi(1)-O(1) bond lengths are 2.39 Å. Both Bi(1)-O(3) bond lengths are 2.37 Å. Both Bi(1)-O(4) bond lengths are 2.38 Å. As(1) is bonded to four equivalent O(2) atoms to form AsO4 tetrahedra that share edges with two equivalent Na(1)O6 octahedra and edges with two equivalent Na(2)O6 octahedra. All As(1)-O(2) bond lengths are 1.72 Å. There are four inequivalent O sites. In the first O site, O(2) is bonded in a distorted T-shaped geometry to one Na(1), one Na(2), and one As(1) atom. In the second O site, O(3) is bonded in a 3-coordinate geometry to one Na(2), one C(1), and one Bi(1) atom. In the third O site, O(1) is bonded in a distorted single-bond geometry to one Na(1), one C(1), and one Bi(1) atom. In the fourth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Na(1), one Na(2), one C(1), and one Bi(1) atom.