DOE OSTI2020
(Al8O21)2(SO4)4(O2)7 crystallizes in the monoclinic P2_1 space group. The structure is two-dimensional and consists of four oxygen molecules; four sulfuric acid molecules; two trioxidane molecules; and one Al8O21 sheet oriented in the (1, 0, -1) direction. In the Al8O21 sheet, there are eight inequivalent Al sites. In the first Al site, Al is bonded to six O atoms to form a mixture of edge and corner-sharing AlO6 octahedra. The corner-sharing octahedral tilt angles are 33°. There are a spread of Al–O bond distances ranging from 1.89–1.96 Å. In the second Al site, Al is bonded to six O atoms to form distorted edge-sharing AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.85–1.99 Å. In the third Al site, Al is bonded to six O atoms to form a mixture of distorted edge and corner-sharing AlO6 octahedra. The corner-sharing octahedral tilt angles are 36°. There are a spread of Al–O bond distances ranging from 1.84–1.94 Å. In the fourth Al site, Al is bonded to six O atoms to form AlO6 octahedra that share a cornercorner with one AlO5 trigonal bipyramid and edges with three AlO6 octahedra. There are a spread of Al–O bond distances ranging from 1.85–1.97 Å. In the fifth Al site, Al is bonded in a 5-coordinate geometry to five O atoms. There are a spread of Al–O bond distances ranging from 1.76–1.92 Å. In the sixth Al site, Al is bonded to six O atoms to form a mixture of distorted edge and corner-sharing AlO6 octahedra. The corner-sharing octahedra tilt angles range from 33–36°. There are a spread of Al–O bond distances ranging from 1.83–1.96 Å. In the seventh Al site, Al is bonded in a distorted rectangular see-saw-like geometry to four O atoms. There are a spread of Al–O bond distances ranging from 1.74–1.82 Å. In the eighth Al site, Al is bonded to five O atoms to form distorted corner-sharing AlO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 30°. There are a spread of Al–O bond distances ranging from 1.77–1.87 Å. There are twenty-one inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to two Al atoms. In the second O site, O is bonded in a trigonal non-coplanar geometry to three Al atoms. In the third O site, O is bonded in a distorted trigonal non-coplanar geometry to three Al atoms. In the fourth O site, O is bonded in a trigonal non-coplanar geometry to three Al atoms. In the fifth O site, O is bonded in a water-like geometry to two Al atoms. In the sixth O site, O is bonded in a bent 120 degrees geometry to two Al atoms. In the seventh O site, O is bonded in a water-like geometry to two Al atoms. In the eighth O site, O is bonded in a water-like geometry to two Al atoms. In the ninth O site, O is bonded in a water-like geometry to two Al atoms. In the tenth O site, O is bonded in a water-like geometry to two Al atoms. In the eleventh O site, O is bonded in a bent 150 degrees geometry to two Al atoms. In the twelfth O site, O is bonded in a 2-coordinate geometry to two Al and one O atom. The O–O bond length is 1.53 Å. In the thirteenth O site, O is bonded in a distorted trigonal non-coplanar geometry to three Al atoms. In the fourteenth O site, O is bonded in a 2-coordinate geometry to two Al and one O atom. In the fifteenth O site, O is bonded in an L-shaped geometry to two Al atoms. In the sixteenth O site, O is bonded in a bent 150 degrees geometry to two Al atoms. In the seventeenth O site, O is bonded in a bent 150 degrees geometry to two Al atoms. In the eighteenth O site, O is bonded in a single-bond geometry to one Al atom. In the nineteenth O site, O is bonded in a bent 150 degrees geometry to two Al atoms. In the twentieth O site, O is bonded in a bent 150 degrees geometry to two Al atoms. In the twenty-first O site, O is bonded in a single-bond geometry to one Al atom.