ISOMERIZATION SOLVOLYSIS ION ASSOCIATION AND SOLVATION OF CIS- AND TRANS-DICHLOROBIS(ETHYLENEDIAMINE)COBALT (3) CATIONS IN PROTIC AND IN DIPOLAR APROTIC SOLVENTS

Solubilities of the chlorides and perchlorates of the cis- and trans-[CoCl2(en)2]+ cations in the protic solvents water and methanol and in the dipolar aprotic solvents dimethylformamide (DMF), dimethylacetamide (DMA), tetramethylene sulfone (TMS), and dimethyl sulfoxide (DMSO) have been measured. The solvent activity coefficients, for transfer of these isomeric cations from DMA to other solvents, have been calculated in terms of a reasonable extrathermodynamic assumption. It has thus been possible to calculate solvent activity coefficients for ion pairs and for model transition states, which are based on a dissociative mechanism for isomerization and solvolysis. A different model must be used for the transition states for at least some solvolysis reactions. The isomerization equilibrium constants in water and in methanol, in which solvents it cannot be measured directly, have been estimated from the observed value in DMA. © 1968, American Chemical Society. All rights reserved.