Anions of the hydrogen-bonded thymine dimer: ab initio study

Theoretical calculations have been performed to determine the ability of the hydrogen-bonded thymine dimer to form stable anions. The major conclusions of this work are: (i) three of the hydrogen-bonded conformers of the thymine dimer can form stable dipole-bound anions with excess electrons; (ii) thymine dimer can form a covalent anion that has a structure dissimilar from the structures of the neutral dimer; (iii) in the covalent thymine-dimer anion the excess electron is localized in a pi -orbital on one of the thymine molecules and this molecule shows an out-of-plane distortion; (iv) the covalent thymine-dimer anion is stable with respect to an adiabatic electron detachment. (C) 2001 Elsevier Science B.V. All rights reserved.