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Density functional theory study of the bis‐3‐benzo‐crown ethers and their complexes with alkali metal cations Na + , K + , Rb + and Cs +
Author(s) -
Zhang Yu,
Wang Xueye,
Luo Benhua,
Xia Yong
Publication year - 2012
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1895
Subject(s) - chemistry , lone pair , alkali metal , density functional theory , valence (chemistry) , binding energy , crystallography , natural bond orbital , metal , computational chemistry , valence electron , molecular orbital , atomic orbital , aromaticity , inorganic chemistry , molecule , electron , atomic physics , organic chemistry , physics , quantum mechanics
The binding interactions of bis‐3‐benzo‐15‐crown‐5 ethers and bis‐3‐benzo‐18‐crown‐6 ethers (neutral hosts) with a series of alkali metal cations Na + , K + , Rb + and Cs + (charged guests) were investigated using quantum chemical density functional theory. Different optimized structures, binding energies and various thermodynamic parameters of free crown ethers and their metal cation complexes were obtained based on the Becke, three‐parameter, Lee–Yang–Parr functional using mixed basis set (C, H, O, Na + and K + using 6‐31 g, and the heavier cation Rb + and Cs + using effective core potentials). Natural bond orbital analysis is conducted on the optimized geometric structures. The main types of driving force host–guest interactions are investigated. The electron donating O offers a lone pair of electrons to the contacting LP* (1‐center valence antibond lone pair) orbitals of metal cations. The bis‐3‐benzocrown ethers are assumed to have sandwich‐like conformations, considering the binding energies to gauge the exact interactions with alkali cations. It is found that there are two different types of complexes: one is a tight ion pair and the other is a separated ion pair. Copyright © 2011 John Wiley & Sons, Ltd.