X-ray Single-Crystal Analysis of Na₂H[(P_0.52As_0.48)O₄]·7H₂O

Abstract

The crystal structure of Na₂H[(P_0.52As_0.48)O₄]·7H₂O at room temperature belongs to the P2₁/n space group and is isomorphous to Na₂HAsO₄·7H₂O and Na₂HPO₄·7H₂O. The structure was solved and refined with 6310 independent reflections with R₁ = 0.0518 and Rw₂ = 0.0811 by means of Mo K_α radiation. The lattice parameters are: a = 9.3250(7), b = 11.0063(8), c = 10.5602(7)Å, β = 95.530(2)° and Z = 4. This crystal structure is built up from discrete (P,As)O₄^3- tetrahedra connected by O-H…O hydrogen bonds and through the electrostatic actions of the Na⁺ cations. The mean (P,As)-O distance is intermediate between those of P-O, and the As-O distance is not consistent with those of Na₂HAsO₄·7H₂O and Na₂HPO₄·7H₂O.