On the Gas Phase Hydrogen Bond Complexes between Formic Acid and Hydroperoxyl Radical. A Theoretical Study

9 pages, 5 tables, 4 figures.We present a systematic study on the gas-phase hydrogen-bonded complexes formed between formic acid and hydroperoxyl radical, which has been carried out by using B3LYP and CCSD(T) theoretical approaches in connection with the 6-311+G(2df,2p) basis set. For all complexes we have employed the AIM theory by Bader and the NBO partition scheme by Weinhold to analyze the bonding features. We have found 17 stationary points, and 11 of them present a cyclic structure. Their computed stabilites vary from 0.3 to 11.3 kcal/mol, depending on several factors, such as involvment in the hydrogen bond interaction, the geometrical constraints, and the possible concurrence of further effects such as resonance-assisted hydrogen bonds or inductive effects. In addition, three stationary points correspond to transition structures involving a double proton-transfer process whose features are also analyzed.The financial support for this work was provided by the Dirección General de Investigación Científica y Técnica (DGICYT, grant CTQ2005-07790) and by the Generalitat de Catalunya (Grant 2005SGR00111). M.T. is thankful for the financial support by C.S.I.C. through Beca de Introducción a la Investigación (B.O.E. 29-07-1999). The calculations described in this work were performed at the Centre de Supercomputació de Catalunya (CESCA) and the Centro de Supercomputación de Galicia (CESGA), whose services are gratefully acknowledged.Peer reviewe