New aqua-fluoride and fluoride indium(III) complexes with monodentate-coordinated molecules of 4-amino-1,2,4-triazole. Synthesis, crystal structure, and thermogravimetry, DSC, and 19F,1H NMR study

Abstract A molecular aqua-fluoride complex of indium(III) InF 3 (H 2 O)(C 2 H 4 N 4 ) 2 ( I ) has been synthesized for the first time, along with its anhydrous analogue – InF 3 (C 2 H 4 N 4 ) 2 ( II ), which has been obtained by thermal dehydration of I. The crystal structure of I is formed by molecular complexes [InF 3 (H 2 O)(C 2 H 4 N 4 ) 2 ] linked through O–H⋯F and N–H⋯F hydrogen bonds. The structure of the compound II appeared to be chainlike; linear chains of the composition [ I N F 3 ( C 2 H 4 H 4 ) 2 ] 0 ∞ 1 are formed as a result of linking the isolated molecules of the complexes I by In–F–In bridge bonds, in which vacancies of the removed H 2 O molecules are occupied by F atoms of the neighboring molecules. The isolated chains are linked into a three-dimensional framework by N–H⋯F hydrogen bonds. In both compounds, In is coordinated by two neutral molecules of 4-amino-1,2,4-triazole. A distinctive feature of the InF 3 (H 2 O)(C 2 H 4 N 4 ) 2 compound is the presence of three different ligands in the coordination sphere of the indium atom: fluorine and, molecules of H 2 O and 4-amino-1,2,4-triazole.The thermal behavior and character of ionic motions have been investigated by means of thermogravimetry (TG, DTG, DTA), DSC and 19 F, 1 H NMR spectroscopy.