Abstract

Calculations of high-spin isomers of MO₄V₂₀\({\text{O}}_{{46}}^{{n-}}\) anions (S = 9) with MO₄ tetraoxo anions located in the inner and outer spheres of the mixed-valence V₂₀O₄₆ cage have been performed by the density functional theory method. It has been shown that for all systems the endohedral isomers are considerably more favorable than the exohedral isomers. For the complexes with transition metal atoms M (M = Ti, V, Cr), the centered ortho isomer MO₄@V₂₀\({\text{O}}_{{46}}^{{n-}}\) is clearly more preferable. For the complexes with main-group metal atoms (M = Si, Ge, P, As, S, Se), the meta isomer MO₃@V₂₀\({\text{O}}_{{47}}^{{n-}}\) has been localized in addition to ortho-MO₄@V₂₀\({\text{O}}_{{46}}^{{n-}}\). The meta isomer has a pyramidal МО₃ anion and the fourth oxygen atom bound to a trivalent vanadium atom of the cage through an inner О=V^III bond. For complexes with \({\text{SO}}_{4}^{{2-}}\) and \({\text{SeO}}_{4}^{{2-}}\) dianions, both ortho and meta structures do not correspond to stationary points of the potential energy surface: upon optimization, they convert without a barrier to the MO₂@V₂₀\({\text{O}}_{{48}}^{{2-}}\) isomer with two М−О−V^III bridges and two inner О=V^III bonds. The character of geometric distortions, normal mode shifts, and electron and spin density redistribution between the inserted MO₄ guest and the cage as compared with isolated \({\text{MO}}_{4}^{{n-}}\) and V₂₀O₄₆ systems has been considered. The results are compared with previous calculations of MO₄@V₂₀\({\text{O}}_{{50}}^{{n-}}\) complexes with the same anions into the valence-saturated V₂₀O₅₀ cluster. The stability and structure of the “nested” V₄O₆@V₂₀O₅₀ (S = 9) cluster with the more complex tetrahedral guest V₄O₆ inside the V₂₀O₅₀ cage are predicted.

中文翻译：

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价价V 20 O 46团簇内球形钒酸盐与MO 4四氧阴离子配合物的理论研究。

摘要

MO的高自旋异构体的计算₄ V ₂₀ \（{\文本{ö}} _ {{46}} ^ {{N - }} \）阴离子（小号= 9）与MO ₄位于内四氧阴离子V ₂₀ O ₄₆混合笼的外球是用密度泛函理论方法进行的。已经表明，对于所有体系，内面异构体比外面异构体更为有利。对于具有过渡金属原子M（M = Ti，V，Cr）的配合物，居中的邻位异构体MO ₄ @V ₂₀ \（{\ text {O}} _ {{46}} ^ {{n-}} \\ ）显然更可取。对于具有主族金属原子的配合物（M = Si，Ge，P，As，S，Se），间位异构体MO ₃ @V ₂₀ \（{\ text {O}} _ {{47}} ^ {除了oro -MO ₄ @V ₂₀ \（{\ text {O}} _ {{46}} ^ {{n-}} \）之外，{n-}} \）也已本地化。异构体具有棱锥МО的元₃阴离子和通过内О= V结合到保持架的三价钒原子第四氧原子^III键。适用于\（{\ text {SO}} _ {4} ^ {{2-}} \）和\（{\ text {SeO}} _ {4} ^ {{2-}} \）_二价离子，邻位和亚位结构均不对应于势能面的固定点：优化后，它们对MO ₂ @V ₂₀ \（{\ text {O}} _ {{48}} ^无障碍地转换{{2 - }} \）异构体具有两个М-О-V ^III桥和两个内О= V ^III键。与孤立的\（{\ text {MO}} _ {4} ^ {{n-}} \相比，MO ₄来宾和笼子之间的几何畸变，正态模偏移以及电子和自旋密度重新分布的特征）和V ₂₀ O ₄₆系统已被考虑。将结果与MO ₄ @V _20的先前计算进行比较\（{\ text {O}} _ {{50}} ^ {{n-}} \）将具有相同阴离子的化合物络合到化合价的V ₂₀ O ₅₀簇中。预测了“嵌套” V ₄ O ₆ @V ₂₀ O ₅₀（S = 9）团簇的稳定性和结构，该簇在V ₂₀ O ₅₀笼内具有更复杂的四面体客体V ₄ O ₆。