Vibrational spectral studies of solutions at elevated temperatures and pressures. X. Raman spectral study of aqueous cadmium bromide solutions at 25 and 200°C

The Raman spectra of cadmium bromide solutions with bromide to cadmium mole ratios varying from 1.0 to 9.74 were studied at 200°C. Factor analysis revealed that three complexes contributed to the spectra. From a comparison with previous results at 25°C these species were identified as CdBr₂, CdBr₃^–, and CdBr₄^2– cadmium existed as the tetrabromo complex, CdBr₄^2–, at mole ratios greater than 5.99. A formation constant of 7±2 was determined for CdBr₄^2– at 200°C. No evidence of Cd(H₂O)₆²⁺ or CdBr⁺ was found, although electroneutrality dictates that one or both of these species must exist at low mole ratios.