Study of the thermal behaviour of [Cr(NH3)6]MF6 (M=CR, Al, Fe, Ga and In) and [Cr(NH3)6]F3·HF·H2O

Abstract

The thermal behaviour of the hexamminechromium hexafluorometallates and [Cr(NH3)6]F3. HF·H2O was investigated by non-reciprocal quasi-isobaric thermal analysis, X-ray diffraction and i.r. spectroscopy. Reduction of chromium(III) was not observed, neither during the decomposition [Cr(NH3)6]F3·HF·H2O nor during the decomposition of any of the title hexamminechromium hexafluorometallates. Obviously this reduction is not promoted by the coordinative Cr−N bonds, neither these in the starting materials nor those in the intermediately formed phases. Under non-reciprocal quasi-isobaric conditions, hexamminechromium hexafluorometallates are ideal precursors for preparing mixed cationic fluorides both in the rhombohedral modification and in the modification of the hexagonal tungsten bronze type structure.