Struktur und Eigenschaften des blauen Chrom(II)-chlorid-tetrahydrats CrCl2. 4H2O

Structure and Properties of the Blue Chromium(II) Chloride Tetrahydrate CrCl₂.4H₂O The blue chromium(II) chloride tetrahydrate CrCl₂. 4 H₂O crystallizes monoclinic in the space group P2₁/c with a = 5.904, b = 7.339, c = 8.347 Å and β = 110.10°. The unit cell contains two isolated complexes in which the chromium atoms are coordinated by four short bonded water molecules with square planar configuration (Cr? O = 2.078 Å) and by two chlorine atoms in trans-configuration with long bonds (Cr? Cl = 2.758 Å). This structure may be described by the formula {Cr(H₂O)₄]Cl₂}. The absorption spectra are discussed on the basis of the structure determination.