A DFT Study of Tin- and Crown-Ether-Based Host Molecules Capable of Binding Anions and Cations Simultaneously
A DFT Study of Tin- and Crown-Ether-Based Host Molecules Capable of Binding Anions and Cations Simultaneously
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能够同时结合阴离子和阳离子的锡基和冠醚基主体分子的 DFT 研究
DOI：
10.1002/ejic.200390171
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
P. Geerlings
中科院分区：
文献类型：
--
作者：
R. Vivas;F. Proft;M. Biesemans,;R. Willem,;P. Geerlings
报道了一系列基于锡和冠醚的主体化合物（即，三甲基衍生物[18]-冠-6-C6 H3COOSn（CH 3）3和[15]-冠-5-C6 H3COOSn（CH 3）3}能够同时结合阳离子和阴离子。B3 LYP泛函与6- 31 G * 基组一起用于原子C，H，N，O，S，Na和K，3- 21 G * 基组用于Sn，以深入了解决定这些化合物与中性分子丙酮和H2O，SCN−阴离子以及Na+和K+阳离子相互作用性质的因素。与这些分子的相互作用强度模式解释了使用一系列的反应性描述符，如福井功能，硬度，局部柔软度，和MEP（分子静电势）。在本文研究的所有情况下，与Na+的络合物比与K+的络合物更稳定，这与阳离子的大小和冠醚中的可用体积有关。此外，这一发现也与Na+相对于K+的更大硬度以及冠醚部分的硬环境相结合一致。这个区域也进行了分析，通过计算的静电势，这表明，高度负的值与内部区域的空腔的冠，该区域因此是适合亲电攻击。HSAB原理，根据局部柔软度和福井函数来表征反应位点，为冠醚苯甲酸酯的锡原子对SCN−、丙酮和水的反应性提供了有力的解释。HSAB的概念也被成功地用来解释两种冠醚中的锡原子优先与SCN−的氮原子而不是硫原子结合。这一结果证实了所考虑的化合物中的锡原子表现为硬原子。总的来说，这些结果非常适合与以前的实验测量的NMR光谱数据，并表明，这种分子的相互作用可以预测和解释使用DFT计算和DFT为基础的反应性描述符，以及MEP计算。（© Wiley-VCH Verlag GmbH & Co. KGaA，69451魏因海姆，德国，2003）
DFT calculations are reported for a series of tin- and crown-ether-based host compounds {i.e., the trimethyl derivatives [18]-crown-6-C6H3COOSn(CH3)3 and [15]-crown-5-C6H3COOSn(CH3)3} capable of binding cations and anions simultaneously. The B3LYP functional together with the 6-31G* basis set was used for the atoms C, H, N, O, S, Na and K and the 3-21G* basis set for Sn in order to obtain insights into the factors determining the nature of the interactions of these compounds with the neutral molecules acetone and H2O, the SCN− anion, and the Na+ and K+ cations. The interaction strength pattern with these molecules was explained by the use of a series of reactivity descriptors such as the Fukui function, hardness, local softness, and the MEP (molecular electrostatic potential). In all cases studied in this paper, the complexes with Na+ were more stable than those with K+, correlating with the size of the cation and the volume available in the crown ether. Moreover, this finding is also in accordance with the greater hardness of Na+ relative to K+, in combination with the hard environment of the crown ether moiety. This region was also analysed by computation of electrostatic potentials, which showed that highly negative values are associated with the inside region of the cavity of the crown, this region thus being amenable to electrophilic attack. The HSAB principle, characterising the reactive sites on the basis of local softness and the Fukui function, provided a firm explanation of the reactivity of the tin atom of the crown ether benzocarboxylate towards SCN−, acetone and water. The HSAB concept was also successfully used to explain the preference of the tin atoms in both crown ethers to bind with the nitrogen atom rather than the sulfur atom of SCN−. This result is a confirmation that the tin atoms in the compounds under consideration behave as hard atoms. Overall, these results fit remarkably well with previous experimentally measured NMR spectroscopy data and demonstrate that the interactions of this kind of molecules can be predicted and interpreted by the use of DFT calculations and DFT-based reactivity descriptors, as well as MEP calculations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)