Exchange of ammine‐ and fluorido‐ligands in complex salts : the series [Cr(NH3)6][AlF6], [Cr(NH3)5F][SiF6] and K2[Cr(NH3)4F2][Si(NH3)0.5F5.5]2

Abstract

The three amminechromium(III) complex compounds [Cr(NH3)6][AlF6], [Cr(NH3)5F][SiF6] and K2[Cr(NH3)4F2][Si(NH3)0.5F5.5]2 were obtained from ammonothermal synthesis at Tmax=724 K and pmax=2120 bar. Crystal structures were determined from single crystal X‐ray diffraction. The gradual exchange of ammine ligands by fluoride ligands in the amminechromium(III) ions is reflected by an intriguing change in color. The mutual ligand exchange between ammonia ligands and fluoride ions occurs in both the cations and the anions, indicating the various dissolved species present under the synthetic conditions.