Untersuchung von Eisen(II)phosphiten im Hinblick auf die Ausbildung von Wasserstoffbindungen

Ferrous phosphites FeHPO₃·3 H₂O, FeH₂P₂O₅, FeH₄P₂O₆·1/2 H₂O and FeH₁₀P₄O₁₂·4 H₂O were studied using X-ray powder patterns, thermography, electron reflectance spectroscopy, magnetic susceptibility measurements andRaman and infrared molecular spectra. The results obtained indicate that all the phosphites studied contain an approximately octahedral coordination sphere consisting of oxygen atoms, which produces a weak crystal field around the iron atom. Phosphite FeHPO₃·3 H₂O contains an HPO₃ ^2– anion with the symmetry decreased from point groupC _3v toC _s. Ferrous diphosphite FeH₂P₂O₅ contains a non-linear P–O–P bond with a valence angle of 159°. The hydrogen bonds between the water molecule and the HPO₃ ^2– anion indicate a positive hydratation of the phosphite anion. Medium-strong or strong hydrogen bonds, 258–270 pm long, correspond to mutual interactions of the anions in the crystal lattice of hydrogenphosphites. Hydrogen bonding in hydrogenphosphites causes a decrease in theDq values.