Proton Transfer in a Bare Superacid-Amine Complex: A Microwave and Computational Study of Trimethylammonium Triflate
Proton Transfer in a Bare Superacid-Amine Complex: A Microwave and Computational Study of Trimethylammonium Triflate
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纯超酸-胺络合物中的质子转移：三氟甲磺酸三甲基铵的微波和计算研究
DOI：
10.1021/acs.jpca.1c03345
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Leopold, K.R.
中科院分区：
文献类型：
--
作者：
Love, N.;Huff, A.K.;Leopold, K.R.
用傅里叶变换微波光谱在超音速射流中观察了三甲胺（(CH3)3N）与三氟甲烷磺酸（triflic acid, CF3SO3H）形成的配合物。光谱数据，最值得注意的是14n核四极偶联常数，结合计算结果在几个层次的理论，明确地证明了完全或接近完全的质子转移从三酸到三甲胺络合。因此，该体系最好被视为气相的三甲基三酸铵离子对。Brønsted酸和碱的1:1配合物中形成孤立的离子对是不寻常的，可能是由于三酸的强酸性引起的。基于质子亲和和库仑相互作用能的简单能量论证可以用来合理化这一结果。
The complex formed from trimethylamine ((CH3)3N) and trifluoromethanesulfonic acid (triflic acid, CF3SO3H) has been observed by Fourier transform microwave spectroscopy in a supersonic jet. Spectroscopic data, most notably14N nuclear quadrupole coupling constants, are combined with computational results at several levels of theory to unambiguously demonstrate complete or near-complete proton transfer from the triflic acid to the trimethylamine upon complexation. Thus, the system is best regarded as a trimethylammonium triflate ion pair in the gas phase. The formation of an isolated ion pair in a 1:1 complex of a Brønsted acid and base is unusual and likely arises due to the strong acidity of triflic acid. Simple energetic arguments based on proton affinities and the Coulomb interaction energy can be used to rationalize this result.