Collect. Czech. Chem. Commun. 1987, 52, 1742-1747

The determination of crystal structure of chromium(II) phosphite dihydrate, CrHPO3 2 H2O

Jiří Bryndaa, Bohumil Kratochvílb and Ivana Císařovác

a Department of Inorganic Chemistry, Charles University, 128 40 Prague 2
b Department of Mineralogy, Prague Institute of Chemical Technology, 166 28 Prague 6
c Institute of Physics, Czechoslovak Academy of Sciences, 180 40 Prague 8


The crystal structure of CrHPO3.2 H2O has been solved by the heavy atom method. The compound crystallizes in the orthorhombic space group P212121 with the unit cell parameters a = 679·25(8), b = 915·61(8), c = 752·2(1) pm, Z = 4. The structure was refined to the final reliability factor R = 0·043 for 1 040 observed reflexions (I > 1·96σ(I)). The structure consists of chains formed by CrO6 octahedra connected each other in vertices. The chains are interconnected by phosphite tetrahedra HPO3. Hydrogen bridges of water-phosphite tetrahedron and water-water types form space cross-linking of the whole structure. Bond distances Cr-O in the tetragonally distorted octahedron range from 201·2 to 304·9 pm. The interatomic distances P-O in phosphite tetrahedron are between 152·1 and 152·7 pm. The degree of the distorsion DISQ of HPO3 tetrahedron and CrO6 octahedron is discussed on the basis of known structures of phosphites and chromium(II) compounds.