CHARGE-TRANSFER MOLECULAR-COMPLEXES OF THIANES WITH SIGMA AND PI-ELECTRON ACCEPTORS

Charge-transfer complexes of cyclic thioethers with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone; tetracyanoethylene; chloranil as pi-acceptors and with iodine as a sigma-acceptor, have been investigated. The spectral characteristics and stability of the formed CT complexes were examined, and are discussed in terms of the donor molecular structure, the nature of the electron acceptor and the solvent polarity. It is deduced that the formed CT complexes are mainly of the weak n-pi or n-sigma type, where the ground-state wave function is described primarily in terms of the nonbonding structure (D-A). The ionization potentials of the donors were calculated based on the CT energies of their CT complexes. Moreover, solid 1:1 CT complexes were synthesized and characterized.