Vanadium(II) chemistry. Part II. Spectral and magnetic studies of the hydrated halides

Abstract

The hydrated halides VX₂,6H₂O (X = Br, I), VY₂,4H₂O (Y = Cl, Br, or I) and VZ₂,2H₂O (Z = Cl, or Br) have been characterised by magnetic and diffuse reflectance spectral measurements down to liquid-nitrogen temperatures. The hexahydrates appear to have ionic structures, [V(H₂O)₆X₂], with hexa-aquo-ions. The tetrahydrates have the tetragonal structures, trans-[V(H₂O)₄Y₂], and provide the first examples of the effects of tetragonal distortion on the electronic spectra of vanadium(II). The dihydrates show weak tetragonal distortion. They have polymeric, tetragonal structures with bridging halogen atoms and exhibit antiferromagnetic behaviour. The other hydrates are magnetically dilute, with moments near to the spin-only value (3·87 B.M.) and invariant with temperature.