Crystal structure and NMR study of 4-amino-1,2,4-triazolium hexafluoridoniobate(V) and hexafluoridotantalate(V)

Abstract

4-Amino-1,2,4-triazolium hexafluoridoniobate(V) and hexafluoridotantalate(V) (C₂H₅N₄)MF₆ (M = Nb, Ta) crystallizing in the monoclinic system (space group P2₁/n) are synthesized for the first time and their crystal structures and spectroscopic features are studied by single crystal X-ray diffraction and ¹H and ¹⁹F NMR spectroscopy. The crystal structures of isostructural (C₂H₅N₄)MF₆ compounds are formed of octahedral complex [MF₆]^– anions (M = Nb, Ta) and monoprotonated heterocyclic 4-amino-1,2,4-triazolium cations (C₂H₅N₄)⁺ organized in a three-dimensional structure via N–H···F and N–H···N hydrogen bonds. The character and types of ion motions in the fluoride sublattice of (C₂H₅N₄)MF₆ are determined in a wide temperature range.