TOPOLOGY AND BASICITY IN POLYOXOVANADATES: AB INTITIO STUDY OF THE CAGED MOLECULES $[V_{18}O_{42}]^{12}$ AND $[V_{7} O_{12}(O_{3}PH)_{6}]$
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Date
1997
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Ohio State University
Abstract
Ab initio Hartree-Fock calculations have been carried out on the octadecavanadate ion $[V_{18}O_{42}]^{12-}(1)$, On its protonated derivative $[H_{4}V_{18}O_{42}]^{8-}(2)$, and on the vanadophosphate cluster $[V_{7}O_{12}(O_{3}PH)_{6}]^{-}(3)$, taken as a model for $[V_{7}O_{12}(O_{3}PR)_{6}]^{-} (3^{\prime})$. The spheroidal clusters (2) and $(3^{\prime})$ have been recently characterized as ``electronically inverse hosts” in the encapsulation complexes $Cs_{9}[X@H_{4}V_{18}O_{42}]\cdot 12H_{2}O (X = Br, I)$ and $(PH_{4}P)_{2}[Cl@V_{7}O_{12}(O_{3}PPh)_{6}]$. An estimate of the electrostatic potential distribution including the contribution of the lattice potential yields highly positive values of the potential inside the host cavities for (2) and (3). Those values are larger than the electrostatic potential computed at a vacant chloride site of the CsCl crystal, thus explaining the thermodynamic stability of the encapsulated anions.
Description
Author Institution: Laboratoire de Chimie Quantique, UPR 139 du CNRS Universit\'e Louis Pasteur; Laboratoire de Cristallographie et Mod\'{e}lisation des Mat\'{e}raux Min\'{e}raux et Biologigues, CCM^{3}B, URA 809 du CNRS, University Henri Poincar\'e-Nancy