Ca5Ga2As6 crystallizes in the orthorhombic Pbam space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms to form CaAs6 octahedra that share corners with two equivalent Ca(1)As6 octahedra, corners with three equivalent Ca(3)As6 octahedra, edges with two equivalent Ca(1)As6 octahedra, edges with four equivalent Ga(1)Ca2As4 tetrahedra, and  a faceface with one Ca(3)As6 octahedra. The corner-sharing octahedral tilt angles range from 35-52°. In the second Ca site, Ca(2) is bonded in a 9-coordinate geometry to two equivalent Ga(1), one As(1), two equivalent As(3), and four equivalent As(2) atoms. In the third Ca site, Ca(3) is bonded to two equivalent As(1) and four equivalent As(3) atoms to form CaAs6 octahedra that share corners with six equivalent Ca(1)As6 octahedra, corners with eight equivalent Ga(1)Ca2As4 tetrahedra, edges with two equivalent Ca(3)As6 octahedra, and faces with two equivalent Ca(1)As6 octahedra. The corner-sharing octahedral tilt angles range from 35-52°. Ga(1) is bonded to two equivalent Ca(2), one As(2), one As(3), and two equivalent As(1) atoms to form distorted GaCa2As4 tetrahedra that share corners with four equivalent Ca(3)As6 octahedra, corners with two equivalent As(3)Ca6Ga pentagonal bipyramids, edges with four equivalent Ca(1)As6 octahedra,  an edgeedge with one As(3)Ca6Ga pentagonal bipyramid, and edges with two equivalent Ga(1)Ca2As4 tetrahedra. The corner-sharing octahedral tilt angles range from 43-62°. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 6-coordinate geometry to one Ca(2), one Ca(3), two equivalent Ca(1), and two equivalent Ga(1) atoms. In the second As site, As(2) is bonded in a 8-coordinate geometry to two equivalent Ca(1), four equivalent Ca(2), one Ga(1), and one As(2) 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 Ga(1) atom to form distorted AsCa6Ga pentagonal bipyramids that share corners with two equivalent As(3)Ca6Ga pentagonal bipyramids, corners with two equivalent Ga(1)Ca2As4 tetrahedra,  an edgeedge with one As(3)Ca6Ga pentagonal bipyramid,  an edgeedge with one Ga(1)Ca2As4 tetrahedra, and faces with two equivalent As(3)Ca6Ga pentagonal bipyramids.
Ca5Ga2As6 crystallizes in the orthorhombic Pbam space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent As(1), two equivalent As(2), and two equivalent As(3) atoms to form CaAs6 octahedra that share corners with two equivalent Ca(1)As6 octahedra, corners with three equivalent Ca(3)As6 octahedra, edges with two equivalent Ca(1)As6 octahedra, edges with four equivalent Ga(1)Ca2As4 tetrahedra, and  a faceface with one Ca(3)As6 octahedra. The corner-sharing octahedral tilt angles range from 35-52°. There is one shorter (2.98 Å) and one longer (3.00 Å) Ca(1)-As(1) bond length. Both Ca(1)-As(2) bond lengths are 3.02 Å. Both Ca(1)-As(3) bond lengths are 3.00 Å. In the second Ca site, Ca(2) is bonded in a 9-coordinate geometry to two equivalent Ga(1), one As(1), two equivalent As(3), and four equivalent As(2) atoms. Both Ca(2)-Ga(1) bond lengths are 3.33 Å. The Ca(2)-As(1) bond length is 3.19 Å. Both Ca(2)-As(3) bond lengths are 3.03 Å. There are two shorter (3.08 Å) and two longer (3.20 Å) Ca(2)-As(2) bond lengths. In the third Ca site, Ca(3) is bonded to two equivalent As(1) and four equivalent As(3) atoms to form CaAs6 octahedra that share corners with six equivalent Ca(1)As6 octahedra, corners with eight equivalent Ga(1)Ca2As4 tetrahedra, edges with two equivalent Ca(3)As6 octahedra, and faces with two equivalent Ca(1)As6 octahedra. The corner-sharing octahedral tilt angles range from 35-52°. Both Ca(3)-As(1) bond lengths are 3.02 Å. All Ca(3)-As(3) bond lengths are 3.02 Å. Ga(1) is bonded to two equivalent Ca(2), one As(2), one As(3), and two equivalent As(1) atoms to form distorted GaCa2As4 tetrahedra that share corners with four equivalent Ca(3)As6 octahedra, corners with two equivalent As(3)Ca6Ga pentagonal bipyramids, edges with four equivalent Ca(1)As6 octahedra,  an edgeedge with one As(3)Ca6Ga pentagonal bipyramid, and edges with two equivalent Ga(1)Ca2As4 tetrahedra. The corner-sharing octahedral tilt angles range from 43-62°. The Ga(1)-As(2) bond length is 2.69 Å. The Ga(1)-As(3) bond length is 2.47 Å. Both Ga(1)-As(1) bond lengths are 2.51 Å. There are three inequivalent As sites. In the first As site, As(1) is bonded in a 6-coordinate geometry to one Ca(2), one Ca(3), two equivalent Ca(1), and two equivalent Ga(1) atoms. In the second As site, As(2) is bonded in a 8-coordinate geometry to two equivalent Ca(1), four equivalent Ca(2), one Ga(1), and one As(2) atom. The As(2)-As(2) bond length is 2.50 Å. In the third As site, As(3) is bonded to two equivalent Ca(1), two equivalent Ca(2), two equivalent Ca(3), and one Ga(1) atom to form distorted AsCa6Ga pentagonal bipyramids that share corners with two equivalent As(3)Ca6Ga pentagonal bipyramids, corners with two equivalent Ga(1)Ca2As4 tetrahedra,  an edgeedge with one As(3)Ca6Ga pentagonal bipyramid,  an edgeedge with one Ga(1)Ca2As4 tetrahedra, and faces with two equivalent As(3)Ca6Ga pentagonal bipyramids.