Structural reintepretation and ascertainment of the clathrate nature of compounds of general formula MX2 · 6Py (M - metal(2), X - anion, Py - pyridine)

Parameters of elementary cells and Ccca space group of eleven compounds belonging to [MPy4X] · 2Py general formula (M = Cd, Co, Cu, Ni, Zn X = Br, I, NO3, HCOO) are determined by means of x-ray structure analysis. These compounds are shown for the first time to form with five known ones the essential group of clathrates representing a combined packing of [MPy4X2] (master) complex molecules and pyridine molecules (guest) retained in crystalline skeleton cavities by van-der-Waals forces. On the basis of the results of investigation and of published data analysis one makes a conclusion that at least several of known, but structurally not characterized compounds of MX2 · 6Py gross formula are the clathrates. 18 refs