Study of chromium(II) phosphites

Abstract

Chromium(II) phosphites CrHPO3.H2O, CrDPO3.2 D2O, CrH4P2O6.H2O and CrD4P2O6.D2O were studied in the solid state by powder X-ray diffraction, thermography, electronic reflection spectroscopy, magnetic susceptibility measurements, and Raman and infrared absorption spectroscopy. The phosphite CrHPO3.H2O involves an anion whose point symmetry is reduced from C3v to Cs. The vibrational spectra of the phosphite CrDPO3.2 D2O were discussed in terms of the correlation and factor group approach. Chromium(II) dihydrogenbis(orthophosphite) involves in the crystal lattice two hydrogen bonds, lengths 269 ± 2 pm and 286 ± 2 pm. The stronger hydrogen bonding is originated on the interaction of an oxygen atom and a hydroxyl group bonded at two different phosphorus atoms, and brings about among others a lowering of the crystal field strength in the hydrogenphosphite. The weaker hydrogen bond is probably formed between the anion and the water molecule.