Sharma Bhaskar, Neela Y Indra, Narahari Sastry G
Center for Molecular Modelling, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad, Telangana, 500 607, India.
J Comput Chem. 2016 Apr 30;37(11):992-1004. doi: 10.1002/jcc.24288. Epub 2016 Feb 2.
Quantum chemical calculations have been performed at CCSD(T)/def2-TZVP level to investigate the strength and nature of interactions of ammonia (NH3 ), water (H2 O), and benzene (C6 H6 ) with various metal ions and validated with the available experimental results. For all the considered metal ions, a preference for C6 H6 is observed for dicationic ions whereas the monocationic ions prefer to bind with NH3 . Density Functional Theory-Symmetry Adapted Perturbation Theory (DFT-SAPT) analysis has been employed at PBE0AC/def2-TZVP level on these complexes (closed shell), to understand the various energy terms contributing to binding energy (BE). The DFT-SAPT result shows that for the metal ion complexes with H2 O electrostatic component is the major contributor to the BE whereas, for C6 H6 complexes polarization component is dominant, except in the case of alkali metal ion complexes. However, in case of NH3 complexes, electrostatic component is dominant for s-block metal ions, whereas, for the d and p-block metal ion complexes both electrostatic and polarization components are important. The geometry (M(+) -N and M(+) -O distance for NH3 and H2 O complexes respectively, and cation-π distance for C6 H6 complexes) for the alkali and alkaline earth metal ion complexes increases down the group. Natural population analysis performed on NH3 , H2 O, and C6 H6 complexes shows that the charge transfer to metal ions is higher in case of C6 H6 complexes.
已在CCSD(T)/def2-TZVP水平上进行量子化学计算，以研究氨（NH₃）、水（H₂O）和苯（C₆H₆）与各种金属离子相互作用的强度和性质，并与现有的实验结果进行了验证。对于所有考虑的金属离子，观察到二价离子优先与C₆H₆结合，而一价离子则更倾向于与NH₃结合。已在PBE0AC/def2-TZVP水平上对这些配合物（闭壳层）采用密度泛函理论-对称适配微扰理论（DFT-SAPT）分析，以了解对结合能（BE）有贡献的各种能量项。DFT-SAPT结果表明，对于与H₂O的金属离子配合物，静电成分是结合能的主要贡献者，而对于C₆H₆配合物，除碱金属离子配合物外，极化成分占主导。然而，在NH₃配合物的情况下，s区金属离子的静电成分占主导，而对于d区和p区金属离子配合物，静电和极化成分都很重要。碱金属和碱土金属离子配合物的几何结构（NH₃和H₂O配合物分别为M(+) -N和M(+) -O距离，C₆H₆配合物为阳离子-π距离）在同族中向下增加。对NH₃、H₂O和C₆H₆配合物进行的自然布居分析表明，C₆H₆配合物向金属离子的电荷转移更高。
