CaAlSi crystallizes in the trigonal P3m1 space group. There are five inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to three equivalent Al(1), three equivalent Al(5), three equivalent Si(3), and three equivalent Si(4) atoms to form a mixture of distorted face and edge-sharing CaAl6Si6 cuboctahedra. In the second Ca site, Ca(2) is bonded to three equivalent Al(2), three equivalent Al(3), three equivalent Si(1), and three equivalent Si(2) atoms to form a mixture of distorted face and edge-sharing CaAl6Si6 cuboctahedra. In the third Ca site, Ca(3) is bonded to three equivalent Al(3), three equivalent Al(4), three equivalent Si(2), and three equivalent Si(5) atoms to form a mixture of face and edge-sharing CaAl6Si6 cuboctahedra. In the fourth Ca site, Ca(4) is bonded to three equivalent Al(4), three equivalent Al(5), three equivalent Si(3), and three equivalent Si(5) atoms to form a mixture of face and edge-sharing CaAl6Si6 cuboctahedra. In the fifth Ca site, Ca(5) is bonded to three equivalent Al(1), three equivalent Al(2), three equivalent Si(1), and three equivalent Si(4) atoms to form a mixture of distorted face and edge-sharing CaAl6Si6 cuboctahedra. There are five inequivalent Al sites. In the first Al site, Al(1) is bonded in a 9-coordinate geometry to three equivalent Ca(1), three equivalent Ca(5), and three equivalent Si(4) atoms. In the second Al site, Al(2) is bonded in a 9-coordinate geometry to three equivalent Ca(2), three equivalent Ca(5), and three equivalent Si(1) atoms. In the third Al site, Al(3) is bonded in a 9-coordinate geometry to three equivalent Ca(2), three equivalent Ca(3), and three equivalent Si(2) atoms. In the fourth Al site, Al(4) is bonded in a distorted trigonal planar geometry to three equivalent Ca(3), three equivalent Ca(4), and three equivalent Si(5) atoms. In the fifth Al site, Al(5) is bonded in a 9-coordinate geometry to three equivalent Ca(1), three equivalent Ca(4), and three equivalent Si(3) atoms. There are five inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to three equivalent Ca(2), three equivalent Ca(5), and three equivalent Al(2) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to three equivalent Ca(2), three equivalent Ca(3), and three equivalent Al(3) atoms. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to three equivalent Ca(1), three equivalent Ca(4), and three equivalent Al(5) atoms. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to three equivalent Ca(1), three equivalent Ca(5), and three equivalent Al(1) atoms. In the fifth Si site, Si(5) is bonded in a distorted trigonal planar geometry to three equivalent Ca(3), three equivalent Ca(4), and three equivalent Al(4) atoms.
CaAlSi crystallizes in the trigonal P3m1 space group. There are five inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to three equivalent Al(1), three equivalent Al(5), three equivalent Si(3), and three equivalent Si(4) atoms to form a mixture of distorted face and edge-sharing CaAl6Si6 cuboctahedra. All Ca(1)-Al(1) bond lengths are 3.41 Å. All Ca(1)-Al(5) bond lengths are 3.39 Å. All Ca(1)-Si(3) bond lengths are 3.19 Å. All Ca(1)-Si(4) bond lengths are 3.17 Å. In the second Ca site, Ca(2) is bonded to three equivalent Al(2), three equivalent Al(3), three equivalent Si(1), and three equivalent Si(2) atoms to form a mixture of distorted face and edge-sharing CaAl6Si6 cuboctahedra. All Ca(2)-Al(2) bond lengths are 3.40 Å. All Ca(2)-Al(3) bond lengths are 3.38 Å. All Ca(2)-Si(1) bond lengths are 3.17 Å. All Ca(2)-Si(2) bond lengths are 3.20 Å. In the third Ca site, Ca(3) is bonded to three equivalent Al(3), three equivalent Al(4), three equivalent Si(2), and three equivalent Si(5) atoms to form a mixture of face and edge-sharing CaAl6Si6 cuboctahedra. All Ca(3)-Al(3) bond lengths are 3.19 Å. All Ca(3)-Al(4) bond lengths are 3.26 Å. All Ca(3)-Si(2) bond lengths are 3.37 Å. All Ca(3)-Si(5) bond lengths are 3.25 Å. In the fourth Ca site, Ca(4) is bonded to three equivalent Al(4), three equivalent Al(5), three equivalent Si(3), and three equivalent Si(5) atoms to form a mixture of face and edge-sharing CaAl6Si6 cuboctahedra. All Ca(4)-Al(4) bond lengths are 3.24 Å. All Ca(4)-Al(5) bond lengths are 3.18 Å. All Ca(4)-Si(3) bond lengths are 3.37 Å. All Ca(4)-Si(5) bond lengths are 3.26 Å. In the fifth Ca site, Ca(5) is bonded to three equivalent Al(1), three equivalent Al(2), three equivalent Si(1), and three equivalent Si(4) atoms to form a mixture of distorted face and edge-sharing CaAl6Si6 cuboctahedra. All Ca(5)-Al(1) bond lengths are 3.12 Å. All Ca(5)-Al(2) bond lengths are 3.12 Å. All Ca(5)-Si(1) bond lengths are 3.35 Å. All Ca(5)-Si(4) bond lengths are 3.35 Å. There are five inequivalent Al sites. In the first Al site, Al(1) is bonded in a 9-coordinate geometry to three equivalent Ca(1), three equivalent Ca(5), and three equivalent Si(4) atoms. All Al(1)-Si(4) bond lengths are 2.44 Å. In the second Al site, Al(2) is bonded in a 9-coordinate geometry to three equivalent Ca(2), three equivalent Ca(5), and three equivalent Si(1) atoms. All Al(2)-Si(1) bond lengths are 2.44 Å. In the third Al site, Al(3) is bonded in a 9-coordinate geometry to three equivalent Ca(2), three equivalent Ca(3), and three equivalent Si(2) atoms. All Al(3)-Si(2) bond lengths are 2.43 Å. In the fourth Al site, Al(4) is bonded in a distorted trigonal planar geometry to three equivalent Ca(3), three equivalent Ca(4), and three equivalent Si(5) atoms. All Al(4)-Si(5) bond lengths are 2.42 Å. In the fifth Al site, Al(5) is bonded in a 9-coordinate geometry to three equivalent Ca(1), three equivalent Ca(4), and three equivalent Si(3) atoms. All Al(5)-Si(3) bond lengths are 2.44 Å. There are five inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to three equivalent Ca(2), three equivalent Ca(5), and three equivalent Al(2) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to three equivalent Ca(2), three equivalent Ca(3), and three equivalent Al(3) atoms. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to three equivalent Ca(1), three equivalent Ca(4), and three equivalent Al(5) atoms. In the fourth Si site, Si(4) is bonded in a 9-coordinate geometry to three equivalent Ca(1), three equivalent Ca(5), and three equivalent Al(1) atoms. In the fifth Si site, Si(5) is bonded in a distorted trigonal planar geometry to three equivalent Ca(3), three equivalent Ca(4), and three equivalent Al(4) atoms.