MOLECULAR-COMPLEXES OF CROWN-ETHERS .3. EFFECT OF CATIONS ON CHARGE-TRANSFER COMPLEXES WITH TCNE

The intermolecular charge transfer complexes (CT) of two crown ethers (CE), viz, B15C5 and DB18C6 (as donors), and tetracyanoethylene (TCNE) , as acceptor, were studied in the W-visible region in dichloroethane (DCE), at 298.2 K. The sequence of addition of the cation was varied i n the case of B15C5 such that in one system the sequence was (CE + Cat ion) + TCNE and in the other (CE + TCNE) + cation. These two systems w ere found to be non-interchangeable, even under reflux conditions, giv ing different K-c values which were explained as being due to the diff erent geometries of the CE. For the first sequence, the values most af fected depended on the fit of the metal cation with the ether cavity, thus in B15C5, Na+ showed the greatest effect, while for DB18C6 it was K+.