Ca5Ga2Sb6 crystallizes in the orthorhombic Pbam space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 9-coordinate geometry to two equivalent Ga(1), one Sb(2), two equivalent Sb(3), and four equivalent Sb(1) atoms. In the second Ca site, Ca(2) is bonded to two equivalent Sb(2) and four equivalent Sb(3) atoms to form CaSb6 octahedra that share corners with six equivalent Ca(3)Sb6 octahedra, corners with eight equivalent Ga(1)Ca2Sb4 tetrahedra, edges with two equivalent Ca(2)Sb6 octahedra, and faces with two equivalent Ca(3)Sb6 octahedra. The corner-sharing octahedral tilt angles range from 33-52°. In the third Ca site, Ca(3) is bonded to two equivalent Sb(1), two equivalent Sb(2), and two equivalent Sb(3) atoms to form CaSb6 octahedra that share corners with two equivalent Ca(3)Sb6 octahedra, corners with three equivalent Ca(2)Sb6 octahedra, edges with two equivalent Ca(3)Sb6 octahedra, edges with four equivalent Ga(1)Ca2Sb4 tetrahedra, and  a faceface with one Ca(2)Sb6 octahedra. The corner-sharing octahedral tilt angles range from 33-52°. Ga(1) is bonded to two equivalent Ca(1), one Sb(1), one Sb(3), and two equivalent Sb(2) atoms to form distorted GaCa2Sb4 tetrahedra that share corners with four equivalent Ca(2)Sb6 octahedra, corners with two equivalent Sb(3)Ca6Ga pentagonal bipyramids, edges with four equivalent Ca(3)Sb6 octahedra,  an edgeedge with one Sb(3)Ca6Ga pentagonal bipyramid, and edges with two equivalent Ga(1)Ca2Sb4 tetrahedra. The corner-sharing octahedral tilt angles range from 44-62°. There are three inequivalent Sb sites. In the first Sb site, Sb(1) is bonded in a 8-coordinate geometry to two equivalent Ca(3), four equivalent Ca(1), one Ga(1), and one Sb(1) atom. In the second Sb site, Sb(2) is bonded in a 6-coordinate geometry to one Ca(1), one Ca(2), two equivalent Ca(3), and two equivalent Ga(1) atoms. In the third Sb site, Sb(3) is bonded to two equivalent Ca(1), two equivalent Ca(2), two equivalent Ca(3), and one Ga(1) atom to form distorted SbCa6Ga pentagonal bipyramids that share corners with two equivalent Sb(3)Ca6Ga pentagonal bipyramids, corners with two equivalent Ga(1)Ca2Sb4 tetrahedra,  an edgeedge with one Sb(3)Ca6Ga pentagonal bipyramid,  an edgeedge with one Ga(1)Ca2Sb4 tetrahedra, and faces with two equivalent Sb(3)Ca6Ga pentagonal bipyramids.
Ca5Ga2Sb6 crystallizes in the orthorhombic Pbam space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 9-coordinate geometry to two equivalent Ga(1), one Sb(2), two equivalent Sb(3), and four equivalent Sb(1) atoms. Both Ca(1)-Ga(1) bond lengths are 3.54 Å. The Ca(1)-Sb(2) bond length is 3.39 Å. Both Ca(1)-Sb(3) bond lengths are 3.24 Å. There are two shorter (3.30 Å) and two longer (3.48 Å) Ca(1)-Sb(1) bond lengths. In the second Ca site, Ca(2) is bonded to two equivalent Sb(2) and four equivalent Sb(3) atoms to form CaSb6 octahedra that share corners with six equivalent Ca(3)Sb6 octahedra, corners with eight equivalent Ga(1)Ca2Sb4 tetrahedra, edges with two equivalent Ca(2)Sb6 octahedra, and faces with two equivalent Ca(3)Sb6 octahedra. The corner-sharing octahedral tilt angles range from 33-52°. Both Ca(2)-Sb(2) bond lengths are 3.19 Å. All Ca(2)-Sb(3) bond lengths are 3.21 Å. In the third Ca site, Ca(3) is bonded to two equivalent Sb(1), two equivalent Sb(2), and two equivalent Sb(3) atoms to form CaSb6 octahedra that share corners with two equivalent Ca(3)Sb6 octahedra, corners with three equivalent Ca(2)Sb6 octahedra, edges with two equivalent Ca(3)Sb6 octahedra, edges with four equivalent Ga(1)Ca2Sb4 tetrahedra, and  a faceface with one Ca(2)Sb6 octahedra. The corner-sharing octahedral tilt angles range from 33-52°. Both Ca(3)-Sb(1) bond lengths are 3.20 Å. There is one shorter (3.17 Å) and one longer (3.23 Å) Ca(3)-Sb(2) bond length. Both Ca(3)-Sb(3) bond lengths are 3.22 Å. Ga(1) is bonded to two equivalent Ca(1), one Sb(1), one Sb(3), and two equivalent Sb(2) atoms to form distorted GaCa2Sb4 tetrahedra that share corners with four equivalent Ca(2)Sb6 octahedra, corners with two equivalent Sb(3)Ca6Ga pentagonal bipyramids, edges with four equivalent Ca(3)Sb6 octahedra,  an edgeedge with one Sb(3)Ca6Ga pentagonal bipyramid, and edges with two equivalent Ga(1)Ca2Sb4 tetrahedra. The corner-sharing octahedral tilt angles range from 44-62°. The Ga(1)-Sb(1) bond length is 2.83 Å. The Ga(1)-Sb(3) bond length is 2.69 Å. Both Ga(1)-Sb(2) bond lengths are 2.72 Å. There are three inequivalent Sb sites. In the first Sb site, Sb(1) is bonded in a 8-coordinate geometry to two equivalent Ca(3), four equivalent Ca(1), one Ga(1), and one Sb(1) atom. The Sb(1)-Sb(1) bond length is 2.86 Å. In the second Sb site, Sb(2) is bonded in a 6-coordinate geometry to one Ca(1), one Ca(2), two equivalent Ca(3), and two equivalent Ga(1) atoms. In the third Sb site, Sb(3) is bonded to two equivalent Ca(1), two equivalent Ca(2), two equivalent Ca(3), and one Ga(1) atom to form distorted SbCa6Ga pentagonal bipyramids that share corners with two equivalent Sb(3)Ca6Ga pentagonal bipyramids, corners with two equivalent Ga(1)Ca2Sb4 tetrahedra,  an edgeedge with one Sb(3)Ca6Ga pentagonal bipyramid,  an edgeedge with one Ga(1)Ca2Sb4 tetrahedra, and faces with two equivalent Sb(3)Ca6Ga pentagonal bipyramids.