The possibility of formation of various ion clusters for lithium salts LiXF6 (X = As, P) is studied. The dynamic matrix of the clusters in a gas phase is calculated by numerical and analytical differentiation of the full energy of clusters in the MO LCAO approximation by the Hartree-Fock-Roothaan (HFR) method with the aid of program package PC GAMESS. Stable ionic clusters are ion pairs Li+[XF6](-) with bi- and tridentate cation coordination relative to the octahedral anion, ion triplets [XF6]Li--(+)[XF6](-) and Li+[YF6]Li--(+) with bi- and tridentate coordination, and ion dimers {Li+[XF6](-)}(2) with bidentate coordination. Trimers {Li+[XF6](-)}(4) and tetramers {Li+[XF6](-)}(4) in the form of symmetrical ring structures with monodentate coordination are stable only for [AsF6](-). For stable ion species, densities of vibrational states and IR spectra are calculated.