CsAl3(SiO4)3 crystallizes in the monoclinic Cc space group. Cs(1) is bonded in a 12-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(10), one O(11), one O(12), one O(7), one O(8), and one O(9) atom to form distorted AlO6 octahedra that share  a cornercorner with one Al(3)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and edges with three equivalent Al(2)O6 octahedra. In the second Al site, Al(2) is bonded to one O(10), one O(11), one O(12), one O(7), one O(8), and one O(9) atom to form distorted AlO6 octahedra that share  a cornercorner with one Al(3)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and edges with three equivalent Al(1)O6 octahedra. In the third Al site, Al(3) is bonded to one O(1), one O(11), one O(3), and one O(5) atom to form AlO4 tetrahedra that share  a cornercorner with one Al(1)O6 octahedra,  a cornercorner with one Al(2)O6 octahedra, and corners with three equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-57°. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O6 octahedra,  a cornercorner with one Al(2)O6 octahedra, and corners with three equivalent Al(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 51-54°. In the second Si site, Si(2) is bonded to one O(2), one O(4), one O(6), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O6 octahedra,  a cornercorner with one Al(2)O6 octahedra, and corners with three equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-54°. In the third Si site, Si(3) is bonded to one O(12), one O(2), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O6 octahedra,  a cornercorner with one Al(2)O6 octahedra, and corners with three equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 45-55°. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent Cs(1), one Al(3), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to two equivalent Cs(1), one Si(2), and one Si(3) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Cs(1), one Al(3), and one Si(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to two equivalent Cs(1), one Si(2), and one Si(3) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to two equivalent Cs(1), one Al(3), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to two equivalent Cs(1), one Si(2), and one Si(3) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Al(1), one Al(2), and one Si(1) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(2), and one Si(2) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Al(1), one Al(2), and one O(10) atom. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Al(1), one Al(2), and one O(9) atom. In the eleventh O site, O(11) is bonded in a trigonal planar geometry to one Al(1), one Al(2), and one Al(3) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(2), and one Si(3) atom.
CsAl3(SiO4)3 crystallizes in the monoclinic Cc space group. Cs(1) is bonded in a 12-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms. There is one shorter (2.99 Å) and one longer (3.38 Å) Cs(1)-O(1) bond length. There is one shorter (3.53 Å) and one longer (3.62 Å) Cs(1)-O(2) bond length. There is one shorter (3.11 Å) and one longer (3.58 Å) Cs(1)-O(3) bond length. There is one shorter (3.66 Å) and one longer (3.79 Å) Cs(1)-O(4) bond length. There is one shorter (3.01 Å) and one longer (3.34 Å) Cs(1)-O(5) bond length. There is one shorter (3.50 Å) and one longer (3.61 Å) Cs(1)-O(6) bond length. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(10), one O(11), one O(12), one O(7), one O(8), and one O(9) atom to form distorted AlO6 octahedra that share  a cornercorner with one Al(3)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and edges with three equivalent Al(2)O6 octahedra. The Al(1)-O(10) bond length is 1.91 Å. The Al(1)-O(11) bond length is 1.81 Å. The Al(1)-O(12) bond length is 2.04 Å. The Al(1)-O(7) bond length is 1.92 Å. The Al(1)-O(8) bond length is 1.88 Å. The Al(1)-O(9) bond length is 1.86 Å. In the second Al site, Al(2) is bonded to one O(10), one O(11), one O(12), one O(7), one O(8), and one O(9) atom to form distorted AlO6 octahedra that share  a cornercorner with one Al(3)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and edges with three equivalent Al(1)O6 octahedra. The Al(2)-O(10) bond length is 1.92 Å. The Al(2)-O(11) bond length is 1.85 Å. The Al(2)-O(12) bond length is 1.88 Å. The Al(2)-O(7) bond length is 1.87 Å. The Al(2)-O(8) bond length is 2.02 Å. The Al(2)-O(9) bond length is 1.87 Å. In the third Al site, Al(3) is bonded to one O(1), one O(11), one O(3), and one O(5) atom to form AlO4 tetrahedra that share  a cornercorner with one Al(1)O6 octahedra,  a cornercorner with one Al(2)O6 octahedra, and corners with three equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-57°. The Al(3)-O(1) bond length is 1.75 Å. The Al(3)-O(11) bond length is 1.76 Å. The Al(3)-O(3) bond length is 1.73 Å. The Al(3)-O(5) bond length is 1.75 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), one O(5), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O6 octahedra,  a cornercorner with one Al(2)O6 octahedra, and corners with three equivalent Al(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 51-54°. The Si(1)-O(1) bond length is 1.62 Å. The Si(1)-O(3) bond length is 1.61 Å. The Si(1)-O(5) bond length is 1.63 Å. The Si(1)-O(7) bond length is 1.69 Å. In the second Si site, Si(2) is bonded to one O(2), one O(4), one O(6), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O6 octahedra,  a cornercorner with one Al(2)O6 octahedra, and corners with three equivalent Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-54°. The Si(2)-O(2) bond length is 1.66 Å. The Si(2)-O(4) bond length is 1.65 Å. The Si(2)-O(6) bond length is 1.66 Å. The Si(2)-O(8) bond length is 1.62 Å. In the third Si site, Si(3) is bonded to one O(12), one O(2), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O6 octahedra,  a cornercorner with one Al(2)O6 octahedra, and corners with three equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 45-55°. The Si(3)-O(12) bond length is 1.61 Å. The Si(3)-O(2) bond length is 1.66 Å. The Si(3)-O(4) bond length is 1.65 Å. The Si(3)-O(6) bond length is 1.66 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent Cs(1), one Al(3), and one Si(1) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to two equivalent Cs(1), one Si(2), and one Si(3) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Cs(1), one Al(3), and one Si(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to two equivalent Cs(1), one Si(2), and one Si(3) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to two equivalent Cs(1), one Al(3), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to two equivalent Cs(1), one Si(2), and one Si(3) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Al(1), one Al(2), and one Si(1) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(2), and one Si(2) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Al(1), one Al(2), and one O(10) atom. The O(9)-O(10) bond length is 1.58 Å. In the tenth O site, O(10) is bonded in a 3-coordinate geometry to one Al(1), one Al(2), and one O(9) atom. In the eleventh O site, O(11) is bonded in a trigonal planar geometry to one Al(1), one Al(2), and one Al(3) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Al(1), one Al(2), and one Si(3) atom.