VIS spectroscopy studies of pseudooctahedral solvation complexes of cobalt(II) ion in mixed solvents

Solvation of cobalt(II) ion in mixed solvents (acetonitrile (AN)-dimethylsulfoxide (DMSO), AN-methanol (MeOH), AN---H₂O, MeOH---H₂O, DMSO---H₂O) has been studied by VIS absorption spectroscopy. A new application of the partial least-squares (PLS) method for the quantitative analysis of the spectral data has allowed to determine the number of solvation complexes and the solvent compositions of their maximum concentration in the solutions investigated. The results have been discussed in respect of the ability of the mixed solvents to solvate preferentially Co(II) ion.