THE SYNTHESIS, VIBRATIONAL SPECTRA, CRYSTAL STRUCTURE AND THERMAL DECOMPOSITION OF (N2H5)3AlF6
A. Rahten, P. Benkiè, A. Jesih
Jožef Stefan Institute, Jamova 39, 1111 Ljubljana, Slovenia
(N2H5)3AlF6 has been synthesized by the reaction of AlF3.3H2O and N2H5F in a water solution. N-N stretching bands of the N2H5+ ions appear as medium band at 969 and as strong band at 955 cm-1 in infrared and at 965 and 955 cm-1 in Raman indicating different environments of the environment sensitive N2H5+ ions. The compound crystallizes in orthorhombic system, space group P212121 (No.19), with a=9.015(2) A, b=9.191(2) A and c=10.479(2) A. (N2H5)3AlF6consists of separated AlF6-3 octahedra, arranged in a distorted f.c.c. fashion. Octahedra are connected through hydrazinium ions and there are two types of strong hydrogen bonds regarding the orientation of NH2-NH3+ units. (N2H5)3AlF6decomposes thermally by exothermic decomposition of hydrazinium(+1) ions to yield the mixture of (NH4)3AlF6 and NH4AlF4 at 243 oC. Further decomposition leads to NH4AlF4at 301 oC and b-AlF3 at 460 oC. The final decomposition product is a-AlF3 at 700oC.