Abstract
The structure and spectral signatures of the protonated homodimer of pyridine in its complex with a poorly coordinating anion have been studied in solution in CDF 3/CDClF 2 down to 120 K and in a single crystal. In both phases, the hydrogen bond is asymmetric. In the solution, the proton is involved in a fast reversible transfer that determines the multiplicity of NMR signals and the sign of the primary H/D isotope effect of -0.95 ppm. The proton resonates at 21.73 ppm that is above any value reported in the past and is indicative of a very short hydrogen bond. By combining X-ray diffraction analysis with model computations, the position of the proton in the crystal has been defined as d(N-H) = 1.123 Å and d(H•••N) = 1.532 Å. The same distances have been estimated using a 15N NMR correlation. The frequency of the protonic out-of-plane bending mode is 822 cm -1 in agreement with Novak's correlation.
Original language | English |
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Pages (from-to) | 8041-8048 |
Number of pages | 8 |
Journal | Journal of Physical Chemistry A |
Volume | 115 |
Issue number | 27 |
DOIs | |
State | Published - Jul 14 2011 |