ON THE THERMAL-DECOMPOSITION OF HYDRAZINIUMPENTAFLUOROMETALLATES N2H6MF5 OF IRON, VANADIUM AND ALUMINUM

The thermal decomposition of the hydraziniumpentafluorometallates of N 2H6FeF5, N2H6VF5 and N2H6AlF5 has been investigated by thermoanalytica l, X-ray and i.r. spectroscopic methods. The thermal decomposition lea ds to ammonium compounds forming in consequence of disproportionation of the hydrazinium cation into ammonia and nitrogen. Under quasi-isoba ric conditions a multistage decomposition mechanism has been detected. No hydrolysis reactions have been observed. In the iron system a part ial reduction of Fe(III) takes place. Consequently NH4Fe2F6 is formed which decomposes via (NH4)1-xFeF4-x (x = 0.6-0.8) with HTB-structure i nto FeF3 and FeF2. In the aluminium and vanadium system the formation of tetragonal (NH4F)y . MF3-phases (y = 0.2-0.8) as intermediates has been observed. Final products of decomposition are VF3 and alpha-AlF3.