STRUCTURE OF POLYMORPHS OF COMPLEX ZIRCONIUM AND HAFNIUM FLUORIDES WITH THE 4-AMINO-1,2,4-TRIAZOLIUM CATION: (C2H5N4)2MF6 (M = Zr, Hf, ZrxHf1-x)
A. V. Gerasimenko, R. L. Davidovich, M. A. Pushilin, V. B. Logvinova
Institute of Chemistry, Far East Branch, Russian Academy of Sciences, Vladivostok, Russia
Keywords: синтез, кристаллическая структура, комплексный фторид, цирконий, гафний, полиморфная модификация, конформер, 4-амино-1,2,4-триазол, synthesis, crystal structure, complex fluoride, zirconium, hafnium, polymorph, conformer, 4-amino-1,2,4-triazole
Abstract
New hybrid organic-inorganic complex zirconium and hafnium fluorides with the 4-amino-1,2,4-triazolium cation (C2H5N4)2MF6 (M = Zr, Hf, Zr x Hf1- x ), which crystallize in two polymorphs (monoclinic ( P 21/ n , Z = 4) and triclinic ( P , Z = 2)) are synthesized and structurally studied for the first time. The structures of both polymorphs are composed of hydrogen bonded (N-H⋯F and C-H⋯F) 4-amino-1,2,4-triazolium cations protonated via the nitrogen atom in site 1 and complex [M2F12]4- anions that are centrosymmetric dimers formed by edge-sharing pentagonal bipyramids MF7 (M = Zr, Hf, Zr x Hf1- x ). It is found that in the structures studied 4-amino-1,2,4-triazolium cation occur simultaneously as cis- and trans- conformers. The packing character of structural units in the unit cells of the studied crystals is discussed along with the structure of the neutral and protonated forms of 4-amino-1,2,4-triazole.
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