Hexafluorosilicates of bis(aminopyridinium). The relationship between H-bonding system and solubility of salts

Pyridinium hexafluorosilicates of the composition (LH)2[SiF6] (I, II, IV, L = 2-aminopyridine, 3-aminopyridine, and 2,6-diaminopyridine) and (LH)2[SiF6]·H2O (III, L = 4-aminopyridine) were separated as crystalline products of interaction of fluorosilicic acid with relevant aminopyridines. The compounds were characterized by IR, mass-spectrometry, potentiometry, solubility data, and in the case of I and IV by X-ray crystallography. The relationship between the salts structure and some physical properties is discussed.