Institut für Chemie und Biochemie, Freie Universität Berlin, Takustrasse 3, 14195 Berlin, Germany.
J Phys Chem A. 2011 Jul 14;115(27):8041-8. doi: 10.1021/jp203543g. Epub 2011 Jun 21.
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 (15)N NMR correlation. The frequency of the protonic out-of-plane bending mode is 822 cm(-1) in agreement with Novak's correlation.
已在 CDF(3)/CDClF(2) 中于低至 120 K 的温度下和在单晶中对吡啶质子化同二聚体与其弱配位阴离子复合物的结构和光谱特征进行了研究。在两相中，氢键都是不对称的。在溶液中，质子参与快速可逆转移，这决定了 NMR 信号的多重性和 --0.95 ppm 的主要 H/D 同位素效应的符号。质子在 21.73 ppm 处共振，高于过去报道的任何值，表明氢键非常短。通过将 X 射线衍射分析与模型计算相结合，确定了晶体中质子的位置为 d(N-H) = 1.123 Å 和 d(H···N) = 1.532 Å。还使用 (15)N NMR 相关法估计了相同的距离。质子面外弯曲模式的频率为 822 cm(-1)，与 Novak 的相关性一致。
