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

The electronic structure of the benzene-tetracyanoethylene electron do nor-acceptor complex is investigated at the HF/6-311G* level of theor y. The computed electronic wave function is analyzed with rigorous int erpretive tools that involve both molecular orbital and density functi onal approaches. The in situ electronegativity difference is calculate d 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 interactio n energy of ca. 33% of the dipole moment. The remaining part of the di pole moment originates from buckling of the tetracyanoethylene moiety. The dependence of the electronegativity difference on the magnitude o f charge transfer is found to be highly nonlinear. (C) 1994 John Wiley and Sons, Inc.