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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >DFT-B3LYP, NPA-, and QTAIM-based study of the physical properties of [M(II)(H_2O)_2(15-crown-5)] (M = Mn, Fe, Co, Ni, Cu, Zn) complexes
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DFT-B3LYP, NPA-, and QTAIM-based study of the physical properties of [M(II)(H_2O)_2(15-crown-5)] (M = Mn, Fe, Co, Ni, Cu, Zn) complexes

机译：基于DFT-B3LYP，NPA和QTAIM的[M（II）（H_2O）_2（15-crown-5）]（M = Mn，Fe，Co，Ni，Cu，Zn）络合物的物理性质的研究

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A density functional theory study of the structure of the title compounds with the divalent metal ions in their high-spin ground state, obtained using B3LYP/ 6-311++G(d,p) in vacuo and in aqueous solution simulated using a polarized continuum medium, is reported for the first time. The modeling reproduces the pseudo pentagonal bipyramidal crystallographic structures very well, including some asymmetry in the equatorial bonds lengths to the crown ether O donors. The very marked asymmetry in the Ni~(2+) structure due to a Jahn-Teller distortion of a d~8 system in a D_(5h) ligand field is also well reproduced. The gas phase binding energies of the complexes follow the order Mn~(2+) < Fe~(2+) < Co~(2+) < Ni~(2+) < Cu~(2+) > Zn~(2+), in precise agreement with the Irving- William series. Both the NPA and Bader charges show there is ligand-to-metal charge transfer; however, the values obtained from the NPA procedure, unlike those obtained from Bader's quantum theory of molecules approach, do not correlate with the electronegativity of the metal ions, the stabilization energies of the solvated complexes or the ionic radii of the metal ions, and so appear to be less reliable. The nature of the bonding between the ligands and the metal ions has been explored using the topological properties of the electron charge density. The metal-ligand bond distances were found to be exponentially correlated with the electron charge density, its Laplacian, and with its curvature in the direction of the bond path atMO bond critical points. While the bonding with coordinated H_2O is predominantly ionic, that to the crown ether donor atoms has some covalent character the extent of which increases across the first transition series. The delocalization indices ofMObonds in these complexes correlate reasonably well with the electron density and its Laplacian at the bond critical points; this therefore provides a rapid and computationally very efficient way of determining these properties, from which insight into the nature of the bonding can be obtained, obviating the need for time-consuming integration over atomic basins.
机译：使用B3LYP / 6-311 ++ G（d，p）在真空中和通过极化模拟的水溶液中获得的具有高旋转基态的二价金属离子的标题化合物结构的密度泛函理论研究连续介质，首次报道。该模型很好地再现了伪五边形双锥体晶体学结构，包括与冠醚O供体的赤道键长不对称。由于D_（5h）配体场中d〜8系统的Jahn-Teller畸变，在Ni〜（2+）结构中出现了非常明显的不对称性。配合物的气相结合能遵循Mn〜（2+） Zn〜（2）的顺序+），与Irving- William系列完全一致。 NPA和Bader电荷都表明存在配体到金属的电荷转移。但是，与从Bader的分子量子理论方法获得的值不同，从NPA程序获得的值与金属离子的电负性，溶剂化配合物的稳定能或金属离子的离子半径等均不相关。似乎不太可靠。利用电子电荷密度的拓扑性质，探索了配体与金属离子之间键合的性质。发现金属-配体键的距离与电子电荷密度，其拉普拉斯算子及其在MO键临界点处的键路径方向上​​的曲率成指数相关。虽然与配位的H_2O的键主要是离子键，但与冠醚供体原子的键具有某些共价键特征，其程度在第一个过渡系列中增加。在这些复合物中，MObond的离域指数与电子密度及其在键临界点处的拉普拉斯关系良好。因此，这提供了一种确定这些性质的快速且计算上非常有效的方法，从中可以洞悉键的性质，从而避免了在原子盆上进行耗时的集成的需求。

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