Octahedral cobalt(III) complexes in dipolar aprotic solvents. III. A new spectrophotometric method for the determination of ion association constants

Abstract

A spectrophotometric method for the evaluation of ion association constants has been developed. This method involves the preparation of solutions containing only the compound under consideration. A function relating the association constants to the concentration of compound and extinction coefficients has been derived. The association constants are best determined by an iterative method using a computer. The association constant for the cis-diohlorobisethylenediaminecobalt(111) cation, cis-[Co en₂ Cl₂]⁺, and chloride ion in NN-dimethylformamide (DMF) at 30º has been calculated by this new method and is compared with that of another established procedure. The association constant has also been determined for the association of cis-[Co en₂ Cl₂]⁺ and iodide in DMF at 30º.