[H(2)amtaz](+) iron fluorides: Synthesis, crystal structures, magnetic and Mossbauer studies

作者：Abdi Insaf; Lhoste Jerome; Leblanc Marc; Maisonneuve Vincent; Greneche Jean Marc; Viau Guillaume; Ben Ali Amor

来源：Journal of Fluorine Chemistry, 2015, 173: 23-28.

DOI：10.1016/j.jfluchem.2015.01.017

• Fluoride
• Iron
• Solvothermal synthesis
• Structure
• Fe-57 Mossbauer spectrometry
• Magnetization

Three new [H(2)amtaz](+) iron fluorides are synthesized at 160 degrees C under microwave heating from FeF2, FeF3, 3-amino-1,2,4-triazole (Hamtaz), HF aqueous solution and ethanol. The exploration of this system shows that the dimensionality of the inorganic networks increases with the HF/(Hamtaz) ratio in the starting solution. The structures of [H(2)amtaz](3)center dot((FeF6)-F-III) (0D) and [H(2)amtaz](2)center dot((FeF5)-F-III) (1D), obtained for HF/(Hamtaz) ratios equal to I and 2.3, are built up from monoprotonated organic cations and isolated FeF6 octahedra or (infinity)[FeF5] chains, respectively. For HF/(Hamtaz) = 8, (infinity)[(Fe2FeF10)-Fe-III-F-II(H(2)amtaz)(2)] layers (2D), resulting from the association of (FeF4N2)-F-II entities and (infinity)[FeF5] chains, appear in (Fe2FeF10)-Fe-III-F-II(H(2)amtaz)(2). Interestingly, these puckered HTB-type layers are neutral. The Fe-57 Mossbauer results are consistent with the presence of both +II and +III valences for iron cations in (Fe2FeF10)-Fe-III-F-II(H(2)amtaz)(2); their proportions 0.65(1)/0.35(1) at 77 K are in fair agreement with the ratio deduced from the crystallographic determination. The presence of dominant antiferromagnetic interactions in (Fe2FeF10)-Fe-III-F-II(H(2)amtaz)(2) as evidenced by magnetization measurements, combined to the cationic topology favors a highly frustrated magnetic structure in the HTB-type layers which results in a very large vertical bar Theta(P)/T-N vertical bar ratio (the Curie-Weiss paramagnetic temperature is Theta(P) = -350 K while the magnetic order temperature is T-N = 18K).

• 出版日期2015-5