Preparation and magnetic properties of some alkali-metal salts of chlorochromate(II) and chlorochromate(III) anions

Abstract

The preparation from melts of the chromium(II) compounds ACrCl₃ and A₂CrCl₄(A = K or Cs) and two chromium(III) compounds K₃CrCl₆ and K₃Cr₂Cl₉ are reported. The compounds ACrCl₃ species are antiferromagnetic while the A₂CrCl₄ species are ferromagnetic and are examples of ferromagnets which are transparent in much of the visible region of the spectrum. The magnetic properties of the chromium(II) compounds are analysed on the basis of one- or two-dimensional nearest-neighbour Heisenberg models. K₃Cr₂Cl₉ Shows evidence of antiferromagnetic exchange. Electronic spectra of some of the compounds are briefly described. Attempts to prepare analogous titanium(II) and vanadium(II) complexes were unsuccessful.