Beschreibung:
<jats:title>Abstract</jats:title><jats:p>When hydroxide ions are added to a solution of Cr(H<jats:sub>2</jats:sub>O)<jats:sub>6</jats:sub><jats:sup>3+</jats:sup> ions at low temperature a well crystallized chromium hydroxide hydrate is formed, corresponding to the formula [Cr(OH)<jats:sub>3</jats:sub>‐(H<jats:sub>2</jats:sub>O)<jats:sub>3</jats:sub>]<jats:sub>∞</jats:sub>. Its structure is the inverse of bayerite type, two thirds of the octahedral M<jats:sup>3+</jats:sup> positions being vacant. It loses water easily and turns into a totally amorphous hydroxide of variable water content. An amorphous hydroxide is also obtained when solutions are alkalized at higher temperatures or when aged solutions (containing polynuclear complexes) are used.</jats:p>