Hussain M Althaf, Mahadevi A Subha, Sastry G Narahari
Center for Molecular Modeling, Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500607, AP, India.
Phys Chem Chem Phys. 2015 Jan 21;17(3):1763-75. doi: 10.1039/c4cp03434a. Epub 2014 Dec 2.
Density functional theory (DFT) calculations have been employed on 165 complexes of onium ions (NH4(+), PH4(+), OH3(+), SH3(+)) and methylated onium ions with CO2, aromatic (C6H6) and heteroaromatic (C5H5X, X = N, P; C4H5Y, Y = N, P; C4H4Z, Z = O, S) systems. The stability of CO2···onium, CO2···π and onium···π complexes was shown to be mediated through various noncovalent interactions such as hydrogen bonding, NH-π, PH-π, OH-π, SH-π, CH-π and π-π. We have discussed 17 complexes wherein the proton transfer occurs between the onium ion and the heteroaromatic system. The binding energy is found to decrease with increasing methyl substitution of the complexes containing onium ions. Binding energy components of all the noncovalent complexes were explored using localized molecular orbital energy decomposition analysis (LMO-EDA). The CO2···π complexes were primarily stabilized by the dispersion term followed by contributions from electrostatic and polarization components. In general, for onium ion complexes with CO2 or π systems, the electrostatic and polarization terms primarily contribute to stabilize the complex. As the number of methyl groups increases on the onium ion, the dispersion term is seen to have a key role in the stabilization of the complex. Quantum theory of atoms in molecules (QTAIM) analysis and charges based on natural population analysis (NPA) in various complexes have also been reported in order to determine the nature of noncovalent interactions in different complexes.
已对鎓离子（NH4(+)、PH4(+)、OH3(+)、SH3(+)）以及甲基化鎓离子与二氧化碳、芳香族（C6H6）和杂芳香族（C5H5X，X = N、P；C4H5Y，Y = N、P；C4H4Z，Z = O、S）体系形成的165种配合物进行了密度泛函理论（DFT）计算。结果表明，CO2···鎓、CO2···π和鎓···π配合物的稳定性是通过各种非共价相互作用介导的，如氢键、NH-π、PH-π、OH-π、SH-π、CH-π和π-π相互作用。我们讨论了17种配合物，其中质子在鎓离子和杂芳香族体系之间发生转移。发现结合能随着含鎓离子配合物甲基取代度的增加而降低。使用定域分子轨道能量分解分析（LMO-EDA）探索了所有非共价配合物的结合能成分。CO2···π配合物主要由色散项稳定，其次是静电和极化成分的贡献。一般来说，对于与CO2或π体系形成的鎓离子配合物，静电和极化项主要有助于稳定配合物。随着鎓离子上甲基数量的增加，色散项在配合物的稳定中起着关键作用。还报道了在各种配合物中基于分子中原子的量子理论（QTAIM）分析和基于自然布居分析（NPA）的电荷，以确定不同配合物中非共价相互作用的性质。
