Spectrophotometric Studies on Sb(III) in Hydrochloric Acid Solutions

Ultraviolet spectroscopy confirms the findings of solubility studies that Sb(III) in 3–12 M hydrochloric acid solutions is present as an equilibrium mixture of SbCl4− and SbCl63− ions. In the presence of H2SO4 a further equilibrium with the SbCl3(HSO4)− ion is found. The spectrum of the SbCl63− ion in solution is unlike the diffuse reflectance spectrum of this anion in Co(NH3)6SbCl6 but is similar to that in K3SbCl6. The Raman spectrum of 2 M SbCl3 in 2.8 M hydrochloric acid is shown to be due to the SbCl4− ion and the spectrum is assigned under C2υ symmetry. The Raman spectrum of the SbCl63− ion in solution is discussed.