SYNTHESIS AND PROPERTIES OF MONOMETALLIC NICKEL(II) AND ZINK AQUA AMMINE MONODIPHOSPHATES

Анотація

New functional materials based on inorganic phosphates are widely used in modern technology and agriculture.

The aim of this study was to prepare solid monometallic mixed salts with a controlled ratio of anionic contents between PO₄³⁻:P₂O₇⁴⁻  have not been described in literature. Phosphates were prepared   by salting out from aqueous ammoniac solution.

The nickel content of the samples was determined gravimetrically with dimethilglyoxime; the zink content, titrimetrically with EDTA; the phosphorus content, gravimetrically by the quinolone-molybdenium method; the ammonia content, by distillation in a vacuum on Seren’ev’s apparatus; and total water and ammonia content, from the weight loss on heating 1023°К in the course of 2 h.

The IR spectra were taken on a Specord 75-IR spectrophotometer. Samples of compounds to be analyzed were prepared in the form of KBr pellets in which the concentration of a substance under study was 0.2-0.3 wt %.

Anions components in phosphates were estimated by using data of qualitative and quantitative paper chromatography.

The X-ray phase analysis was carried out on a DRON-UM1 diffractometer (CuK_α radiation). A single  crystal  of graphite placed  in a diffracted beam was used as  monochromator. The diffraction patterns were taken by the method  of step scanning in the range of angles 2Q = 4…80°. The scanning step was0,05°, and the expose time in a was 3…9 s. The measured diffraction maxima were approximated by the pseudo-Voigt function, with the Kα₁ component being separated out.

         Solid Ni_2,5(PO₄)_1,0×(P₂O₇)_0,5×3,4NH₃×6,0H₂O and Zn_2,5(PO₄)_1,0(P₂O₇)_0,5×2,5NH₃×2,1H₂O with controlled ratio of anionic contents, were prepared   by salting out from aqueous ammoniac solutions.

  For synthesis of  Nickel(II) aqua ammine monodiphosphate as starting reagents we used mechanical mixture consisting of Ni₃(PO₄)₂∙8H₂O and Ni₂P₂O₇·6H₂O with  a specified molar ratio of the PO₄³⁻ і P₂O₇⁴⁻; water ammonia (23÷25% mas) and acetone. Zink aqua ammine monodiphosphate was synthesized by the same method. As starting reagents we used mechanical mixture consisting of Zn₃(PO₄)₂·4H₂O and Zn₂P₂O₇ with  a specified molar ratio of the PO₄³⁻ і P₂O₇⁴⁻

         It should be noted, that Nickel(II) aqua ammine monodiphosphate included more, than Zink aqua ammine monodiphosphate. It may indicate a different saturation degree of metal ion in coordination sphere. For Ni^{2 +} normally coordination number  is 6, and for Zn^{2 +} - 4.

         Nickel(II) and zinc aqua ammine monodiphosphates with a fixed ratio of anionic contents can be only synthesized, when as starting reagents were used mechanical mixtures consisting of Ni₃(PO₄)₂×8H₂O and Ni₂P₂O₇×6H₂O, and Zn₃(PO₄)₂·4H₂O and Zn₂P₂O₇·5H₂O with  a molar ratio of PO₄³⁻:P₂O₇⁴⁻=2:1.