Studies of vanadium(III) aqua chloro complexes and some related compounds

Abstract

Preparative and structural studies on several series of vanadium(111) aqua chloro complexes and related compounds are reported. Results indicate that all compounds contain vanadium(111) in pseudo-octahedral coordination. Evidence is presented from electronic, infrared, and nuclear quadrupole resonance spectra, X-ray powder diffraction, and magnetic data. The compounds of empirical formulae VX₃,6H₂O (X = Cl, Br), RbVCl₄,6H₂O, and Cs₂VX₅,nH₂O (X = Cl, n = 4; X = Br,n = 5) are all shown to contain the green trans-[V(OH₂)₄X₂]⁺ ion. For compounds of formula A^I₂VCl₅,H₂O (A = Cs, Rb, K, NH₄) prior methods of preparation are reexamined and a new method of preparation is given. Physical studies confirm that these compounds contain the red complex ion [V(OH₂)Cl₅I^2-. The salts comprise structures of two types, one for A = Cs, the other for A = K, NH₄, Rb; the latter salts are isostructural with K₂FeCl₅,H₂O. The anhydrous compounds A¹₂VCl₅ (A = Cs, Rb) are also examined and the preparation of the rubidium salt is reported for the first time. For these compounds the magnetic results are interpreted in terms of a weak antiferromagnetic interaction in a proposed polymeric structure and this is supported by other evidence. Some data are reported for VBr₃ and VI₃.