Ba3NbAs3O crystallizes in the orthorhombic Pnma space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to one As(1), four equivalent As(2), and one O(1) atom. In the second Ba site, Ba(2) is bonded to two equivalent As(2), three equivalent As(1), and one O(1) atom to form distorted BaAs5O octahedra that share corners with two equivalent Ba(2)As5O octahedra, corners with four equivalent Nb(1)As3O tetrahedra, edges with two equivalent Ba(2)As5O octahedra, and  an edgeedge with one Nb(1)As3O tetrahedra. The corner-sharing octahedral tilt angles are 2°. Nb(1) is bonded to one As(1), two equivalent As(2), and one O(1) atom to form distorted NbAs3O tetrahedra that share corners with four equivalent Ba(2)As5O octahedra and  an edgeedge with one Ba(2)As5O octahedra. The corner-sharing octahedral tilt angles range from 11-81°. There are two inequivalent As sites. In the first As site, As(1) is bonded to two equivalent Ba(1), three equivalent Ba(2), and one Nb(1) atom to form AsBa5Nb octahedra that share corners with two equivalent As(1)Ba5Nb octahedra, corners with four equivalent O(1)Ba3Nb tetrahedra, edges with two equivalent As(1)Ba5Nb octahedra, edges with eight equivalent As(2)Ba5Nb octahedra, and  an edgeedge with one O(1)Ba3Nb tetrahedra. The corner-sharing octahedral tilt angles are 2°. In the second As site, As(2) is bonded to one Ba(2), four equivalent Ba(1), and one Nb(1) atom to form distorted AsBa5Nb octahedra that share corners with six equivalent As(2)Ba5Nb octahedra, corners with two equivalent O(1)Ba3Nb tetrahedra, edges with four equivalent As(1)Ba5Nb octahedra, edges with four equivalent As(2)Ba5Nb octahedra, and edges with two equivalent O(1)Ba3Nb tetrahedra. The corner-sharing octahedral tilt angles range from 5-58°. O(1) is bonded to one Ba(2), two equivalent Ba(1), and one Nb(1) atom to form OBa3Nb tetrahedra that share corners with four equivalent As(1)Ba5Nb octahedra, corners with four equivalent As(2)Ba5Nb octahedra,  an edgeedge with one As(1)Ba5Nb octahedra, and edges with four equivalent As(2)Ba5Nb octahedra. The corner-sharing octahedral tilt angles range from 23-75°.
Ba3NbAs3O crystallizes in the orthorhombic Pnma space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 6-coordinate geometry to one As(1), four equivalent As(2), and one O(1) atom. The Ba(1)-As(1) bond length is 3.32 Å. There are a spread of Ba(1)-As(2) bond distances ranging from 3.37-3.58 Å. The Ba(1)-O(1) bond length is 2.68 Å. In the second Ba site, Ba(2) is bonded to two equivalent As(2), three equivalent As(1), and one O(1) atom to form distorted BaAs5O octahedra that share corners with two equivalent Ba(2)As5O octahedra, corners with four equivalent Nb(1)As3O tetrahedra, edges with two equivalent Ba(2)As5O octahedra, and  an edgeedge with one Nb(1)As3O tetrahedra. The corner-sharing octahedral tilt angles are 2°. Both Ba(2)-As(2) bond lengths are 3.45 Å. There is one shorter (3.26 Å) and two longer (3.41 Å) Ba(2)-As(1) bond lengths. The Ba(2)-O(1) bond length is 2.70 Å. Nb(1) is bonded to one As(1), two equivalent As(2), and one O(1) atom to form distorted NbAs3O tetrahedra that share corners with four equivalent Ba(2)As5O octahedra and  an edgeedge with one Ba(2)As5O octahedra. The corner-sharing octahedral tilt angles range from 11-81°. The Nb(1)-As(1) bond length is 2.49 Å. Both Nb(1)-As(2) bond lengths are 2.50 Å. The Nb(1)-O(1) bond length is 1.91 Å. There are two inequivalent As sites. In the first As site, As(1) is bonded to two equivalent Ba(1), three equivalent Ba(2), and one Nb(1) atom to form AsBa5Nb octahedra that share corners with two equivalent As(1)Ba5Nb octahedra, corners with four equivalent O(1)Ba3Nb tetrahedra, edges with two equivalent As(1)Ba5Nb octahedra, edges with eight equivalent As(2)Ba5Nb octahedra, and  an edgeedge with one O(1)Ba3Nb tetrahedra. The corner-sharing octahedral tilt angles are 2°. In the second As site, As(2) is bonded to one Ba(2), four equivalent Ba(1), and one Nb(1) atom to form distorted AsBa5Nb octahedra that share corners with six equivalent As(2)Ba5Nb octahedra, corners with two equivalent O(1)Ba3Nb tetrahedra, edges with four equivalent As(1)Ba5Nb octahedra, edges with four equivalent As(2)Ba5Nb octahedra, and edges with two equivalent O(1)Ba3Nb tetrahedra. The corner-sharing octahedral tilt angles range from 5-58°. O(1) is bonded to one Ba(2), two equivalent Ba(1), and one Nb(1) atom to form OBa3Nb tetrahedra that share corners with four equivalent As(1)Ba5Nb octahedra, corners with four equivalent As(2)Ba5Nb octahedra,  an edgeedge with one As(1)Ba5Nb octahedra, and edges with four equivalent As(2)Ba5Nb octahedra. The corner-sharing octahedral tilt angles range from 23-75°.