The properties of anion associates are reviewed. Experimental electronic ab
sorption spectra of anion-anion and anion-cation pairs were analyzed and co
mpared with calculated data. Stability constants of ion pairs were determin
ed in the framework of the theory of outer-sphere association of ions. Anio
n association was shown to be a specific case of typical cation-anion assoc
iation, in which associates of the 2Na(+),[Coedta](-) type play the role of
a complex cation.