Journal of Molecular Modeling

, Volume 19, Issue 10, pp 4139–4145 | Cite as

Enhancing and modulating the intrinsic acidity of imidazole and pyrazole through beryllium bonds

  • Otilia Mó
  • Manuel Yáñez
  • Ibon Alkorta
  • José Elguero
Original Paper


The structure and electronic properties of the complexes formed by the interaction of imidazole and pyrazole with different BeXH(BeX2) (X = H, Me, F, Cl) derivatives have been investigated via B3LYP/6−311+G(3df,2p)//B3LYP/6−31+G(d,p) calculations. The formation of these azole:BeXH(BeX2) complexes is accompanied by a dramatic enhancement of the intrinsic acidity of the azole, as the deprotonated azole is much more stable after the aforementioned interaction. Most importantly, the increase in acidity is so large that the azole:BeXH or azole:BeX2 complexes behave as NH acids, which are stronger than typical oxyacids such as phosphoric acid and oxalic acid. Interestingly, the increase in acidity can be tuned through appropriate selection of the substituents attached to the Be atom, permitting us to modulate the electron-accepting ability of the BeXH or BeX2 molecule.


The association of pyrazole and imidazole with BeX2 derivatives dramatically enhances the acidity of the azole, so the complex imidazole:BeCl2 becomes a NH acid that is stronger than oxalic acid in the gas phase


Intrinsic acidity Imidazole Pyrazole Beryllium bonds DFT calculations 



This work was partially supported by the Dirección General de Investigación (DGI) (projects no. CTQ2009-13129 and CTQ2010-17006), by the project MADRISOLAR2, ref.: S2009PPQ/1533 of the Comunidad Autónoma de Madrid, and by Consolider on Molecular Nanoscience CSC2007-00010. Generous allocations of computing time at the Centro Técnico de Informática (CTI) Consejo Superior de Investigaciones Científicas (CSIC) and at the Centro de Computación Científica (CCC) of the Universidad Autónoma de Madrid (UAM) are also acknowledged.

Supplementary material

894_2012_1682_MOESM1_ESM.pdf (407 kb)
ESM 1 (PDF 407 KB)


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Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Otilia Mó
    • 1
  • Manuel Yáñez
    • 1
  • Ibon Alkorta
    • 2
  • José Elguero
    • 2
  1. 1.Departamento de Química, Módulo 13Universidad Autónoma de Madrid, Campus de Excelencia UAM-CSICMadridSpain
  2. 2.Instituto de Química Médica (IQM-CSIC)MadridSpain

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