DOE OSTI2020
Cs2MgP4(HO2)8 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. Cs1+ is bonded in a 3-coordinate geometry to one H1+ and ten O2- atoms. The Cs–H bond length is 3.34 Å. There are a spread of Cs–O bond distances ranging from 3.08–3.57 Å. Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with four PO4 tetrahedra. There are a spread of Mg–O bond distances ranging from 2.06–2.13 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one MgO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. There are a spread of P–O bond distances ranging from 1.51–1.62 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form PO4 tetrahedra that share a cornercorner with one MgO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedral tilt angles are 50°. There are a spread of P–O bond distances ranging from 1.51–1.64 Å. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one Cs1+ and one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.04 Å) and one longer (1.50 Å) H–O bond length. In the fourth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.05 Å) and one longer (1.46 Å) H–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Cs1+, one Mg2+, and two H1+ atoms. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Cs1+, one P5+, and one H1+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Cs1+, one Mg2+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cs1+, one P5+, and one H1+ atom. In the fifth O2- site, O2- is bonded in a bent 120 degrees geometry to one Cs1+ and two P5+ atoms. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Cs1+, one Mg2+, and one P5+ atom. In the seventh O2- site, O2- is bonded in a bent 120 degrees geometry to one Cs1+, one P5+, and one H1+ atom. In the eighth O2- site, O2- is bonded in a bent 120 degrees geometry to one Cs1+, one P5+, and one H1+ atom.