Geometries and properties of adenine-BH3 complex:: an investigation with density functional theory (DFT) method

Geometries and binding energies are predicted at B3LYP/6-311 + G* level. Single energy calculations using much larger basis sets (6-311 + G(2df,p) and natural bonding analysis have also been carried out on the six optimized conformers. The analyses for the combining interaction between BH3 and adenine with the theory of atom-in-molecules have been performed. The results indicate that the three conformers in which the pyridine-type nitrogen atoms offer their lone pair electrons to the empty p orbital of born atom are the most stable ones with the stabilization energies of 28.09, 27.77, 27.37 kcal/mol (with BSSE correction), respectively, while the conformers in which the pyrrole-type nitrogen atom or carbon atom offers pi electron to the empty orbital of born atom are fairly unstable and the conformer with the nitrogen atom of amino group offer its lone pair electrons to boron has a intergrades stability. (C) 2004 Elsevier B.V. All rights reserved.