Hydrothermal synthesis, thermal decomposition and optical properties of Fe2F5(H2O)(Htaz)(taz)(Hdma)

Abstract

Crystal structure of Fe2F5(H2O)(Htaz)(taz)(Hdma) which crystallizes in the triclinic system space group P1¯ with unit cell parameters a=8.8392(5)Å, b=9.1948(5)Å, c=9.5877(5)Å, α=82.070(3)°, β=63.699(3)°, γ=89.202(3)°, Z=2, and V=690.91(7)Å3, was synthesized under hydrothermal conditions at 393K for 72h, by a mixture of FeF2/FeF3, 1,2,4-triazole molecule (Htaz), and hydrofluoric acid solution (HF 4%) in dimethylformamide solvent (DMF). The main feature of this material is the coexistence of two oxidation states for iron atoms (Fe2+, Fe3+) in the unit cell, which associate by opposite fluorine corners of FeF5N and FeF2N4 octahedra, and/or triazole molecule which originates the 2D produces material. The structure determination, performed from single crystal X-ray diffraction data, lead to the R1/WR2 reliability factors 0.031/0.087. Thermal stability studies (TG/DTG/DTA) show that the decomposition provides in the temperature range 473–773K and no mass loss was detected before 473K. Mass spectrometry (MS) has been used. The optical absorption of the solid was measured at the corresponding λmax using UV–vis diffuse-reflectance spectrum.