Absorption spectra of cobalt(II) chloride and nitrate complexes in aqueous calcium nitrate-ammonium nitrate melts: The influence of solvent composition

Influence of solvent composition, i.e. the salt mole fraction and water content on absorption spectra of cobalt(II) chloride and nitrate in xCa(NO3)2·zH2O-(1 − x)NH4NO3 systems was investigated by spectrophotometric method in the wavelength range 400-800 nm at 55 °C. On the basis of absorption spectra of cobalt(II) chloride and nitrate complexes and overall molar absorption coefficients obtained in 13 investigated systems, the geometry of the complexes formed was studied. Comparing of these spectra with those obtained in anhydrous melts and aqueous solutions, possible coordination of water molecules with cobalt(II) and formation of mixed complexes was considered.