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2009, 113, 15129–15132 Published on Web 10/23/2009
Unexpected Hydrogen Bond Dynamics in Imidazolium-Based Ionic Liquids Jens Thar,† Martin Brehm,† Ari P. Seitsonen,‡ and Barbara Kirchner*,† Wilhelm-Ostwald Institute of Physical and Theoretical Chemistry, UniVersity of Leipzig, Linne´str. 2, D-04103 Leipzig, Germany, and IMPMC, CNRS & UniVersite´ Pierre et Marie Curie, 4 place Jussieu, case 115, F-75252 Paris, France ReceiVed: August 22, 2009; ReVised Manuscript ReceiVed: October 4, 2009
Employing first-principles molecular dynamics simulations, we characterize the structural and dynamical hydrogen bonding in the ionic liquid [C2C1im][SCN]. The geometric picture indicates a superior role for the most acidic hydrogen bond (at H2) as compared to the two other hydrogen atoms at the rear. Despite the structural picture, the hydrogen bond dynamics at H2 is found to decay faster than the according dynamics at the H4 and H5 proton. Neglecting the directionality provides a dynamics which reflects the geometrical analysis. Two movements are identified. First, a fast (
