studies on electronic charge of the hydrogen bond proton in model molecular systems研究氢键质子电子电荷的分子系统模型.pdfVIP

Int. J. Mol. Sci. 2003, 4, 481-485 International Journal of Molecular Sciences ISSN 1422-0067 © 2003 by MDPI /ijms/ Studies on Electronic Charge of the Hydrogen Bond Proton in Model Molecular Systems Henryk Chojnacki Institute of Physical and Theoretical Chemistry, Laboratory of Quantum Chemistry, I-30, Wrocław University of Technology, Wyb. Wyspiañskiego 27, 50-370 Wrocław, Poland E-mail: chojnacki@kchf.ch.pwr.wroc.pl Received: 31 March 2003 / Accepted: 9 April 2003 / Published: 25 June 2003 Abstract: The population analysis of the hydrogen bond atoms was analyzed within the different basis sets for model molecular systems for the ground and low-lying excited electronic states. The Mulliken, Lőwdin and Hirshfeld methods were used in our investigations. It has been shown that normally the proton is transferred, however, in some excited electronic states the hydrogen atom displacement might be responsible for the tautomeric interconversion. Keywords: hydrogen bonding, proton transfer, population analysis. Introduction The proton transfer reactions are the simplest but very important in many chemical problems as well as in some biological processes. It appears that the low-barrier hydrogen bond (LBHB) for this displacement may play fundamental role in stabilizing intermediates in enzymatic reactions an