Abstract: The tetracyanopyridine (4-cyanopyridine and 3-cyanopyridine) was reacted with rare earth nitrates (Ln=La, Gd, Er) under hydrothermal conditions by the Demko-Sharpless method, and four rare earth tetrazolium ionic compound were synthesized safely and effectively, named [Ln(H₂O)₈·3(p-TPD)·2(p-HTPD)·7H₂O], (Ln=La(1), Gd(2), Er(3), p-TPD=4-tetrazolpyridine), [Ln(H₂O)₈·3(m-TPD)·6H₂O], (m-TPD=3-tetrazolpyridine, Ln=Er(4)). These four rare earth tetrazolium ionic compounds were characterized by the single crystal X-ray diffraction, infrared spectroscopy, thermogravimetry, dielectric properties, X-ray powder diffraction. The X-ray single crystal structure analysis shows that the four rare earth tetrazolium compounds were all ionic, and the rare earth metal ions and ligands were in two different layers. The [Ln(H₂O)₈]³⁺ structure unit and p-TPD and water molecules formed a cationic layer through hydrogen bonding, while p-TPD and p-HTPD formed an anion layer through π-π stacking and hydrogen bonding. The cation layer and anion layer alternately form a regular network structure. Moreover, the dielectric properties tests indicate that the compounds 1, 2 have good dielectric properties.

Key words: tetrazole compound, rare earth nitrate, crystal structure, TGA, dielectric property