Materials Data on CdH18Se4(N2O7)2 by Materials Project
CdH2(Se2O7)2(NH4)4 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of four ammonium molecules and one CdH2(Se2O7)2 sheet oriented in the (0, 0, 1) direction. In the CdH2(Se2O7)2 sheet, Cd2+ is bonded to six O2- atoms to form CdO6 octahedra that share corners with two equivalent SeO4 tetrahedra. There are a spread of Cd–O bond distances ranging from 2.33–2.36 Å. 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. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are a spread of Se–O bond distances ranging from 1.71–1.78 Å. In the second Se2- site, Se2- is bonded to four O2- atoms to form SeO4 tetrahedra that share a cornercorner with one CdO6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are a spread of Se–O bond distances ranging from 1.66–1.69 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Cd2+ and one Se2- atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Cd2+ and one Se2- atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one Cd2+ and one Se2- atom. In the fourth O2- site, O2- is bonded in a distorted water-like geometry to one H1+ and one Se2- atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to one Se2- atom. In the sixth O2- site, O2- is bonded in a bent 120 degrees geometry to one H1+ and one Se2- atom. In the seventh O2- site, O2- is bonded in a single-bond geometry to one Se2- atom.