SYNTHESIS AND CHARACTERISATION OF HYDROXYLAMMONIUM FLUOROCHROMATE

Matjaž Kristl, Miha Drofenik

Faculty of Chemistry and Chemical Engineering, University of Maribor, Smetanova 17, SI-2000 Maribor, Slovenia

Ljubo Golič, Amalija Golobič

Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, SI-1000 Ljubljana, Slovenia

Abstract

Reactions in the system Cr – NH₃OHF – HF – H₂O were investigated. Green crystals of a new compound with the formula (NH₃OH)₃CrF₆ have been isolated from the water solution and characterized by chemical analysis. The compound crystallizes as triclinic, P-1, with cell parameters: a = 6.5461(2) Å, b = 6.9347(2) Å, c = 9.4072(3) Å, a = 86.772(1)°, b = 83.804(1)°, g = 70.283(1)°. The effective magnetic moment, μ_eff = 3.82 BM, was calculated from magnetic susceptibility measurements in the temperature range 80-290 K. The thermal decomposition of the compound was studied by TG and DSC analysis. (NH₃OH)₃CrF₆ decomposes above 125 °C in three steps and the residue has been identified by X-ray powder diffraction as α – Cr₂O₃.