Ca3AlAs3 crystallizes in the orthorhombic Pnma space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one As(2), two equivalent As(3), and three equivalent As(1) atoms to form distorted CaAs6 octahedra that share corners with seven equivalent Ca(3)As6 octahedra, corners with three equivalent Al(1)Ca2As4 tetrahedra, edges with four equivalent Ca(1)As6 octahedra, edges with three equivalent Al(1)Ca2As4 tetrahedra, and  a faceface with one Ca(3)As6 octahedra. The corner-sharing octahedral tilt angles range from 43-54°. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to two equivalent Al(1), one As(1), two equivalent As(2), and two equivalent As(3) atoms. In the third Ca site, Ca(3) is bonded to one As(1), two equivalent As(3), and three equivalent As(2) atoms to form distorted CaAs6 octahedra that share corners with seven equivalent Ca(1)As6 octahedra, corners with three equivalent Al(1)Ca2As4 tetrahedra, edges with four equivalent Ca(3)As6 octahedra, edges with two equivalent Al(1)Ca2As4 tetrahedra, and  a faceface with one Ca(1)As6 octahedra. The corner-sharing octahedral tilt angles range from 43-54°. Al(1) is bonded to two equivalent Ca(2), one As(2), one As(3), and two equivalent As(1) atoms to form distorted AlCa2As4 tetrahedra that share corners with three equivalent Ca(1)As6 octahedra, corners with three equivalent Ca(3)As6 octahedra, corners with two equivalent As(3)Ca6Al pentagonal bipyramids, edges with two equivalent Ca(3)As6 octahedra, edges with three equivalent Ca(1)As6 octahedra,  an edgeedge with one As(3)Ca6Al pentagonal bipyramid, and edges with two equivalent Al(1)Ca2As4 tetrahedra. The corner-sharing octahedral tilt angles range from 20-51°. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 7-coordinate geometry to one Ca(2), one Ca(3), three equivalent Ca(1), and two equivalent Al(1) atoms. In the second As site, As(2) is bonded in a 7-coordinate geometry to one Ca(1), two equivalent Ca(2), three equivalent Ca(3), and one Al(1) atom. In the third As site, As(3) is bonded to two equivalent Ca(1), two equivalent Ca(2), two equivalent Ca(3), and one Al(1) atom to form distorted AsCa6Al pentagonal bipyramids that share corners with two equivalent Al(1)Ca2As4 tetrahedra,  an edgeedge with one Al(1)Ca2As4 tetrahedra, and faces with two equivalent As(3)Ca6Al pentagonal bipyramids.
Ca3AlAs3 crystallizes in the orthorhombic Pnma space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one As(2), two equivalent As(3), and three equivalent As(1) atoms to form distorted CaAs6 octahedra that share corners with seven equivalent Ca(3)As6 octahedra, corners with three equivalent Al(1)Ca2As4 tetrahedra, edges with four equivalent Ca(1)As6 octahedra, edges with three equivalent Al(1)Ca2As4 tetrahedra, and  a faceface with one Ca(3)As6 octahedra. The corner-sharing octahedral tilt angles range from 43-54°. The Ca(1)-As(2) bond length is 3.42 Å. Both Ca(1)-As(3) bond lengths are 2.95 Å. There is one shorter (3.06 Å) and two longer (3.19 Å) Ca(1)-As(1) bond lengths. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to two equivalent Al(1), one As(1), two equivalent As(2), and two equivalent As(3) atoms. Both Ca(2)-Al(1) bond lengths are 3.15 Å. The Ca(2)-As(1) bond length is 2.96 Å. Both Ca(2)-As(2) bond lengths are 2.91 Å. Both Ca(2)-As(3) bond lengths are 3.04 Å. In the third Ca site, Ca(3) is bonded to one As(1), two equivalent As(3), and three equivalent As(2) atoms to form distorted CaAs6 octahedra that share corners with seven equivalent Ca(1)As6 octahedra, corners with three equivalent Al(1)Ca2As4 tetrahedra, edges with four equivalent Ca(3)As6 octahedra, edges with two equivalent Al(1)Ca2As4 tetrahedra, and  a faceface with one Ca(1)As6 octahedra. The corner-sharing octahedral tilt angles range from 43-54°. The Ca(3)-As(1) bond length is 3.30 Å. Both Ca(3)-As(3) bond lengths are 3.12 Å. There are two shorter (2.96 Å) and one longer (3.02 Å) Ca(3)-As(2) bond length. Al(1) is bonded to two equivalent Ca(2), one As(2), one As(3), and two equivalent As(1) atoms to form distorted AlCa2As4 tetrahedra that share corners with three equivalent Ca(1)As6 octahedra, corners with three equivalent Ca(3)As6 octahedra, corners with two equivalent As(3)Ca6Al pentagonal bipyramids, edges with two equivalent Ca(3)As6 octahedra, edges with three equivalent Ca(1)As6 octahedra,  an edgeedge with one As(3)Ca6Al pentagonal bipyramid, and edges with two equivalent Al(1)Ca2As4 tetrahedra. The corner-sharing octahedral tilt angles range from 20-51°. The Al(1)-As(2) bond length is 2.50 Å. The Al(1)-As(3) bond length is 2.50 Å. Both Al(1)-As(1) bond lengths are 2.54 Å. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 7-coordinate geometry to one Ca(2), one Ca(3), three equivalent Ca(1), and two equivalent Al(1) atoms. In the second As site, As(2) is bonded in a 7-coordinate geometry to one Ca(1), two equivalent Ca(2), three equivalent Ca(3), and one Al(1) atom. In the third As site, As(3) is bonded to two equivalent Ca(1), two equivalent Ca(2), two equivalent Ca(3), and one Al(1) atom to form distorted AsCa6Al pentagonal bipyramids that share corners with two equivalent Al(1)Ca2As4 tetrahedra,  an edgeedge with one Al(1)Ca2As4 tetrahedra, and faces with two equivalent As(3)Ca6Al pentagonal bipyramids.