ELECTRONIC-STRUCTURE OF THE BENZENE-TETRACYANOETHYLENE COMPLEX - A SYNTHESIS OF MOLECULAR-ORBITAL AND DENSITY-FUNCTIONAL DESCRIPTIONS

The electronic structure of the benzene-tetracyanoethylene electron donor-acceptor complex is investigated at the HF/6-311G** level of theory. The computed electronic wave function is analyzed with rigorous interpretive tools that involve both molecular orbital and density functional approaches. The in situ electronegativity difference is calculated at 3.32 eV, resulting in a charge transfer of 0.016. This extent of charge transfer is found to account for only ca. 17% of the interaction energy of ca. 33% of the dipole moment. The remaining part of the dipole moment originates from buckling of the tetracyanoethylene moiety. The dependence of the electronegativity difference on the magnitude of charge transfer is found to be highly nonlinear. (C) 1994 John Wiley and Sons, Inc.