Spada Lorenzo, Tasinato Nicola, Vazart Fanny, Barone Vincenzo, Caminati Walther, Puzzarini Cristina
Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126, Pisa, Italy.
Dipartimento di Chimica, "Giacomo Ciamician" dell'Università, Via Selmi 2, 40126, Bologna, Italy.
Chemistry. 2017 Apr 6;23(20):4876-4883. doi: 10.1002/chem.201606014. Epub 2017 Mar 21.
The 1:1 complex of ammonia with pyridine is characterized by using state-of-the-art quantum-chemical computations combined with pulsed-jet Fourier-transform microwave spectroscopy. The computed potential energy landscape indicates the formation of a stable σ-type complex, which is confirmed experimentally: analysis of the rotational spectrum shows the presence of only one 1:1 pyridine-ammonia adduct. Each rotational transition is split into several components owing to the internal rotation of NH around its C axis and to the hyperfine structure of both N quadrupolar nuclei, thus providing unequivocal proof that the two molecules form a σ-type complex involving both a N-H⋅⋅⋅N and a C-H⋅⋅⋅N hydrogen bond. The dissociation energy (BSSE- and ZPE-corrected) is estimated to be 11.5 kJ mol . This work represents the first application of an accurate yet efficient computational scheme, designed for the investigation of small biomolecules, to a molecular cluster.
通过结合脉冲喷射傅里叶变换微波光谱的先进量子化学计算，对氨与吡啶的1:1配合物进行了表征。计算得到的势能面表明形成了稳定的σ型配合物，这一点得到了实验证实：对旋转光谱的分析表明仅存在一种1:1吡啶 - 氨加合物。由于NH围绕其C轴的内旋转以及两个N四极核的超精细结构，每个旋转跃迁都分裂成几个组分，从而明确证明这两个分子形成了涉及N - H⋅⋅⋅N和C - H⋅⋅⋅N氢键的σ型配合物。离解能（经基组重叠误差和零点能校正）估计为11.5 kJ mol 。这项工作代表了一种精确而高效的计算方案首次应用于分子簇，该方案是为研究小生物分子而设计的。
