(CaAl2(Si2O7)2)4(O2)3 crystallizes in the monoclinic C2 space group. The structure consists of two trioxidane molecules inside a CaAl2(Si2O7)2 framework. In the CaAl2(Si2O7)2 framework, Ca(1) is bonded in a 5-coordinate geometry to one O(1), one O(10), one O(11), one O(14), one O(16), and one O(2) atom. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(10), one O(5), and one O(8) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. In the second Al site, Al(2) is bonded to one O(11), one O(2), one O(4), and one O(9) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(10), one O(12), one O(6), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Al(1)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(11), one O(12), one O(7), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and corners with two equivalent Al(2)O4 tetrahedra. In the third Si site, Si(3) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. In the fourth Si site, Si(4) is bonded to one O(2), one O(3), one O(5), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1), one Al(1), and one Si(3) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Ca(1), one Al(2), and one Si(4) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Si(3) and one Si(4) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(4) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(3) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(4) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(1) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(2) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one Ca(1), one Al(1), and one Si(1) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Ca(1), one Al(2), and one Si(2) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the thirteenth O site, O(14) is bonded in an L-shaped geometry to one Ca(1) and one O(16) atom. In the fourteenth O site, O(16) is bonded in a distorted single-bond geometry to one Ca(1), one O(14), and one O(16) atom.
(CaAl2(Si2O7)2)4(O2)3 crystallizes in the monoclinic C2 space group. The structure consists of two trioxidane molecules inside a CaAl2(Si2O7)2 framework. In the CaAl2(Si2O7)2 framework, Ca(1) is bonded in a 5-coordinate geometry to one O(1), one O(10), one O(11), one O(14), one O(16), and one O(2) atom. The Ca(1)-O(1) bond length is 2.30 Å. The Ca(1)-O(10) bond length is 2.29 Å. The Ca(1)-O(11) bond length is 2.28 Å. The Ca(1)-O(14) bond length is 2.63 Å. The Ca(1)-O(16) bond length is 2.95 Å. The Ca(1)-O(2) bond length is 2.29 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(10), one O(5), and one O(8) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. The Al(1)-O(1) bond length is 1.80 Å. The Al(1)-O(10) bond length is 1.80 Å. The Al(1)-O(5) bond length is 1.73 Å. The Al(1)-O(8) bond length is 1.73 Å. In the second Al site, Al(2) is bonded to one O(11), one O(2), one O(4), and one O(9) atom to form AlO4 tetrahedra that share  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The Al(2)-O(11) bond length is 1.80 Å. The Al(2)-O(2) bond length is 1.81 Å. The Al(2)-O(4) bond length is 1.73 Å. The Al(2)-O(9) bond length is 1.73 Å. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(10), one O(12), one O(6), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Al(1)O4 tetrahedra. The Si(1)-O(10) bond length is 1.66 Å. The Si(1)-O(12) bond length is 1.64 Å. The Si(1)-O(6) bond length is 1.64 Å. The Si(1)-O(8) bond length is 1.60 Å. In the second Si site, Si(2) is bonded to one O(11), one O(12), one O(7), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and corners with two equivalent Al(2)O4 tetrahedra. The Si(2)-O(11) bond length is 1.66 Å. The Si(2)-O(12) bond length is 1.64 Å. The Si(2)-O(7) bond length is 1.64 Å. The Si(2)-O(9) bond length is 1.60 Å. In the third Si site, Si(3) is bonded to one O(1), one O(3), one O(4), and one O(6) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(4)O4 tetrahedra. The Si(3)-O(1) bond length is 1.65 Å. The Si(3)-O(3) bond length is 1.65 Å. The Si(3)-O(4) bond length is 1.61 Å. The Si(3)-O(6) bond length is 1.64 Å. In the fourth Si site, Si(4) is bonded to one O(2), one O(3), one O(5), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one Al(1)O4 tetrahedra,  a cornercorner with one Al(2)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The Si(4)-O(2) bond length is 1.65 Å. The Si(4)-O(3) bond length is 1.65 Å. The Si(4)-O(5) bond length is 1.61 Å. The Si(4)-O(7) bond length is 1.64 Å. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1), one Al(1), and one Si(3) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Ca(1), one Al(2), and one Si(4) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Si(3) and one Si(4) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(3) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(4) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(3) atom. In the seventh O site, O(7) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(4) atom. In the eighth O site, O(8) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(1) atom. In the ninth O site, O(9) is bonded in a bent 150 degrees geometry to one Al(2) and one Si(2) atom. In the tenth O site, O(10) is bonded in a distorted trigonal planar geometry to one Ca(1), one Al(1), and one Si(1) atom. In the eleventh O site, O(11) is bonded in a distorted trigonal planar geometry to one Ca(1), one Al(2), and one Si(2) atom. In the twelfth O site, O(12) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the thirteenth O site, O(14) is bonded in an L-shaped geometry to one Ca(1) and one O(16) atom. The O(14)-O(16) bond length is 1.24 Å. In the fourteenth O site, O(16) is bonded in a distorted single-bond geometry to one Ca(1), one O(14), and one O(16) atom. The O(16)-O(16) bond length is 1.94 Å.