Structure and vibrational spectra of heteropolycompounds of . composition E5PMo10V2O40xnH2O (E=H,Na). Crystal structure of Na5PMo10V2O40x15H2O

Complete X-ray structural analysis of the crystals Na5PM10xV2O40x15H2O(1) is carried out. The crystals of the salt belong to triclinic crystal system: a=11.618, b=12.373, c=17.936A, α=82.5, β=84.5, γ=65.0 deg, Z=2, sp. gr. P anti 1. Heteropolyanion in I has the Keggin structure of symmetry anti 43 m. In the contrast to corresponding acid water molecules in I do not form their own carcass but participate in its formation alongside with Na+ and anion (HPA); the contact of Na+ is mainly realized with O (end) of HPA. Vibrational spectra (IR and Raman spectra) of solutions and crystal powders are studied and spectral indices of two different ways of cations-HPA interaction are found: 1) with O(bridge) - in this case HPA has pseudokeggin structure; 2) mainly with O(end) - then the HPA structure is of the Keggin type. Relative (to the band of 997 cm-1) intensity of 112 cm-1 band, which is interpreted as rotational, interacting with deformational vibrations of HPA, is the most indicative criterion of such interaction. It is shown that vibrational symmetry of [PMo10V2O40]5- in crystals and solutions is lower the crystallographic one (Osub(h), Tsub(d)). HPA preserves pseudokeggin structure in acid aqueous solutions but under conditions of Na-salt crystallization it transforms into the Keggin one