Charge-transfer complexes of some 5-membered heterocyclics and their annellated derivatives with tetracyanoethylene

Abstract

The electronic spectra and association constants for the interactions between a series of 5-membered ring donors and tetracyanoethylene (TCNE) have been measured. Together with the enthalpy and entropy changes found for the furan-TCNE and thiophen-TCNE interactions the results indicate charge-transfer complex formation in these systems. The spectra have been correlated with the calculated highest-occupied orbital energies of the donor molecules and used to obtain ionization potentials for these molecules. The results indicate that these molecules are π-electron donors.