CaFe5As3 crystallizes in the monoclinic P2_1/m space group. Ca(1) is bonded in a 16-coordinate geometry to one Fe(2), three equivalent Fe(1), three equivalent Fe(4), three equivalent Fe(5), two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent Ca(1), one As(2), and three equivalent As(1) atoms to form distorted FeCa3As4 tetrahedra that share  a cornercorner with one Fe(2)CaAs4 tetrahedra, corners with five equivalent Fe(4)Ca3As4 tetrahedra, corners with seven equivalent Fe(5)Ca3As4 tetrahedra,  an edgeedge with one Fe(2)CaAs4 tetrahedra, edges with two equivalent Fe(1)Ca3As4 tetrahedra, edges with two equivalent Fe(4)Ca3As4 tetrahedra,  a faceface with one Fe(4)Ca3As4 tetrahedra,  a faceface with one Fe(5)Ca3As4 tetrahedra, faces with two equivalent Fe(1)Ca3As4 tetrahedra, and faces with two equivalent Fe(2)CaAs4 tetrahedra. In the second Fe site, Fe(2) is bonded to one Ca(1), one As(1), and three equivalent As(2) atoms to form distorted FeCaAs4 tetrahedra that share  a cornercorner with one Fe(1)Ca3As4 tetrahedra, corners with two equivalent Fe(5)Ca3As4 tetrahedra, corners with two equivalent Fe(2)CaAs4 tetrahedra, corners with four equivalent Fe(4)Ca3As4 tetrahedra,  an edgeedge with one Fe(1)Ca3As4 tetrahedra, edges with two equivalent Fe(5)Ca3As4 tetrahedra, edges with two equivalent Fe(2)CaAs4 tetrahedra, and faces with two equivalent Fe(1)Ca3As4 tetrahedra. In the third Fe site, Fe(3) is bonded in a 5-coordinate geometry to one As(3), two equivalent As(1), and two equivalent As(2) atoms. In the fourth Fe site, Fe(4) is bonded to three equivalent Ca(1), one As(1), and three equivalent As(3) atoms to form distorted FeCa3As4 tetrahedra that share corners with four equivalent Fe(5)Ca3As4 tetrahedra, corners with four equivalent Fe(2)CaAs4 tetrahedra, corners with five equivalent Fe(1)Ca3As4 tetrahedra, edges with two equivalent Fe(1)Ca3As4 tetrahedra, edges with two equivalent Fe(4)Ca3As4 tetrahedra, edges with four equivalent Fe(5)Ca3As4 tetrahedra,  a faceface with one Fe(1)Ca3As4 tetrahedra, faces with two equivalent Fe(4)Ca3As4 tetrahedra, and faces with two equivalent Fe(5)Ca3As4 tetrahedra. In the fifth Fe site, Fe(5) is bonded to three equivalent Ca(1), one As(2), and three equivalent As(3) atoms to form distorted FeCa3As4 tetrahedra that share corners with two equivalent Fe(2)CaAs4 tetrahedra, corners with four equivalent Fe(4)Ca3As4 tetrahedra, corners with seven equivalent Fe(1)Ca3As4 tetrahedra, edges with two equivalent Fe(5)Ca3As4 tetrahedra, edges with two equivalent Fe(2)CaAs4 tetrahedra, edges with four equivalent Fe(4)Ca3As4 tetrahedra,  a faceface with one Fe(1)Ca3As4 tetrahedra, faces with two equivalent Fe(4)Ca3As4 tetrahedra, and faces with two equivalent Fe(5)Ca3As4 tetrahedra. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 9-coordinate geometry to two equivalent Ca(1), one Fe(2), one Fe(4), two equivalent Fe(3), and three equivalent Fe(1) atoms. In the second As site, As(2) is bonded in a 9-coordinate geometry to two equivalent Ca(1), one Fe(1), one Fe(5), two equivalent Fe(3), and three equivalent Fe(2) atoms. In the third As site, As(3) is bonded in a 9-coordinate geometry to two equivalent Ca(1), one Fe(3), three equivalent Fe(4), and three equivalent Fe(5) atoms.
CaFe5As3 crystallizes in the monoclinic P2_1/m space group. Ca(1) is bonded in a 16-coordinate geometry to one Fe(2), three equivalent Fe(1), three equivalent Fe(4), three equivalent Fe(5), two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms. The Ca(1)-Fe(2) bond length is 3.15 Å. There is one shorter (3.16 Å) and two longer (3.23 Å) Ca(1)-Fe(1) bond lengths. There is one shorter (3.12 Å) and two longer (3.20 Å) Ca(1)-Fe(4) bond lengths. There is one shorter (3.11 Å) and two longer (3.19 Å) Ca(1)-Fe(5) bond lengths. Both Ca(1)-As(1) bond lengths are 2.94 Å. Both Ca(1)-As(2) bond lengths are 2.93 Å. Both Ca(1)-As(3) bond lengths are 2.98 Å. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to three equivalent Ca(1), one As(2), and three equivalent As(1) atoms to form distorted FeCa3As4 tetrahedra that share  a cornercorner with one Fe(2)CaAs4 tetrahedra, corners with five equivalent Fe(4)Ca3As4 tetrahedra, corners with seven equivalent Fe(5)Ca3As4 tetrahedra,  an edgeedge with one Fe(2)CaAs4 tetrahedra, edges with two equivalent Fe(1)Ca3As4 tetrahedra, edges with two equivalent Fe(4)Ca3As4 tetrahedra,  a faceface with one Fe(4)Ca3As4 tetrahedra,  a faceface with one Fe(5)Ca3As4 tetrahedra, faces with two equivalent Fe(1)Ca3As4 tetrahedra, and faces with two equivalent Fe(2)CaAs4 tetrahedra. The Fe(1)-As(2) bond length is 2.45 Å. There is one shorter (2.40 Å) and two longer (2.44 Å) Fe(1)-As(1) bond lengths. In the second Fe site, Fe(2) is bonded to one Ca(1), one As(1), and three equivalent As(2) atoms to form distorted FeCaAs4 tetrahedra that share  a cornercorner with one Fe(1)Ca3As4 tetrahedra, corners with two equivalent Fe(5)Ca3As4 tetrahedra, corners with two equivalent Fe(2)CaAs4 tetrahedra, corners with four equivalent Fe(4)Ca3As4 tetrahedra,  an edgeedge with one Fe(1)Ca3As4 tetrahedra, edges with two equivalent Fe(5)Ca3As4 tetrahedra, edges with two equivalent Fe(2)CaAs4 tetrahedra, and faces with two equivalent Fe(1)Ca3As4 tetrahedra. The Fe(2)-As(1) bond length is 2.30 Å. There is one shorter (2.29 Å) and two longer (2.38 Å) Fe(2)-As(2) bond lengths. In the third Fe site, Fe(3) is bonded in a 5-coordinate geometry to one As(3), two equivalent As(1), and two equivalent As(2) atoms. The Fe(3)-As(3) bond length is 2.48 Å. Both Fe(3)-As(1) bond lengths are 2.55 Å. Both Fe(3)-As(2) bond lengths are 2.65 Å. In the fourth Fe site, Fe(4) is bonded to three equivalent Ca(1), one As(1), and three equivalent As(3) atoms to form distorted FeCa3As4 tetrahedra that share corners with four equivalent Fe(5)Ca3As4 tetrahedra, corners with four equivalent Fe(2)CaAs4 tetrahedra, corners with five equivalent Fe(1)Ca3As4 tetrahedra, edges with two equivalent Fe(1)Ca3As4 tetrahedra, edges with two equivalent Fe(4)Ca3As4 tetrahedra, edges with four equivalent Fe(5)Ca3As4 tetrahedra,  a faceface with one Fe(1)Ca3As4 tetrahedra, faces with two equivalent Fe(4)Ca3As4 tetrahedra, and faces with two equivalent Fe(5)Ca3As4 tetrahedra. The Fe(4)-As(1) bond length is 2.41 Å. There are two shorter (2.42 Å) and one longer (2.44 Å) Fe(4)-As(3) bond length. In the fifth Fe site, Fe(5) is bonded to three equivalent Ca(1), one As(2), and three equivalent As(3) atoms to form distorted FeCa3As4 tetrahedra that share corners with two equivalent Fe(2)CaAs4 tetrahedra, corners with four equivalent Fe(4)Ca3As4 tetrahedra, corners with seven equivalent Fe(1)Ca3As4 tetrahedra, edges with two equivalent Fe(5)Ca3As4 tetrahedra, edges with two equivalent Fe(2)CaAs4 tetrahedra, edges with four equivalent Fe(4)Ca3As4 tetrahedra,  a faceface with one Fe(1)Ca3As4 tetrahedra, faces with two equivalent Fe(4)Ca3As4 tetrahedra, and faces with two equivalent Fe(5)Ca3As4 tetrahedra. The Fe(5)-As(2) bond length is 2.45 Å. All Fe(5)-As(3) bond lengths are 2.43 Å. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 9-coordinate geometry to two equivalent Ca(1), one Fe(2), one Fe(4), two equivalent Fe(3), and three equivalent Fe(1) atoms. In the second As site, As(2) is bonded in a 9-coordinate geometry to two equivalent Ca(1), one Fe(1), one Fe(5), two equivalent Fe(3), and three equivalent Fe(2) atoms. In the third As site, As(3) is bonded in a 9-coordinate geometry to two equivalent Ca(1), one Fe(3), three equivalent Fe(4), and three equivalent Fe(5) atoms.