Abstract
Three new [H2amtaz]+ iron fluorides are synthesized at 160 °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 [H2amtaz]3·(FeIIIF6) (0D) and [H2amtaz]2·(FeIIIF5) (1D), obtained for HF/(Hamtaz) ratios equal to 1 and 2.3, are built up from monoprotonated organic cations and isolated FeF6 octahedra or ∞[FeF5] chains, respectively. For HF/(Hamtaz) = 8, ∞[FeIII2FeIIF10(H2amtaz)2] layers (2D), resulting from the association of FeIIF4N2 entities and ∞[FeF5] chains, appear in FeIII2FeIIF10(H2amtaz)2. Interestingly, these puckered HTB-type layers are neutral. The 57Fe Mössbauer results are consistent with the presence of both +II and +III valences for iron cations in FeIII2FeIIF10(H2amtaz)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 FeIII2FeIIF10(H2amtaz)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 ratio (the Curie–Weiss paramagnetic temperature is ΘP = −350 K while the magnetic order temperature is TN = 18 K).