Materials Data on CaP2(HO)4 by Materials Project
Ca(H2PO2)2 crystallizes in the monoclinic C2/c space group. The structure is two-dimensional and consists of two Ca(H2PO2)2 sheets oriented in the (1, 0, 0) direction. Ca2+ is bonded to six O2- atoms to form distorted CaO6 octahedra that share corners with six equivalent PH2O2 tetrahedra and edges with two equivalent CaO6 octahedra. There are two shorter (2.30 Å) and four longer (2.42 Å) Ca–O bond lengths. P1+ is bonded to two H1+ and two O2- atoms to form distorted PH2O2 tetrahedra that share corners with three equivalent CaO6 octahedra. The corner-sharing octahedra tilt angles range from 29–54°. Both P–H bond lengths are 1.42 Å. There is one shorter (1.51 Å) and one longer (1.54 Å) P–O bond length. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one P1+ atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one P1+ atom. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Ca2+ and one P1+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Ca2+ and one P1+ atom.