DOE OSTI2020
P2H8O9 crystallizes in the monoclinic P2_1/c space group. The structure is two-dimensional and consists of one P2H8O9 sheet oriented in the (1, 0, 0) direction. there are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded in a tetrahedral geometry to four O2- atoms. There is one shorter (1.51 Å) and three longer (1.57 Å) P–O bond length. In the second P5+ site, P5+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of P–O bond distances ranging from 1.52–1.57 Å. There are eight inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.03 Å) and one longer (1.53 Å) H–O bond length. In the second H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.03 Å) and one longer (1.56 Å) H–O bond length. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the fourth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.02 Å) and one longer (1.57 Å) H–O bond length. In the fifth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.03 Å) and one longer (1.53 Å) H–O bond length. In the sixth H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.02 Å) and one longer (1.63 Å) H–O bond length. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the eighth H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 1.01 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to one P5+ and one H1+ atom. In the second O2- site, O2- is bonded in a trigonal planar geometry to one P5+ and two H1+ atoms. In the third O2- site, O2- is bonded in a water-like geometry to one P5+ and one H1+ atom. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to one P5+ and one H1+ atom. In the fifth O2- site, O2- is bonded in a trigonal planar geometry to one P5+ and two H1+ atoms. In the sixth O2- site, O2- is bonded in a distorted water-like geometry to three H1+ atoms. In the seventh O2- site, O2- is bonded in a bent 120 degrees geometry to one P5+ and one H1+ atom. In the eighth O2- site, O2- is bonded in a bent 120 degrees geometry to one P5+ and one H1+ atom. In the ninth O2- site, O2- is bonded in a bent 120 degrees geometry to one P5+ and one H1+ atom.