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Title: Site-selective halogenation of mixed-valent vanadium oxide clusters
Here, we expand on the synthesis and characterization of chloride-functionalized polyoxovanadate-alkoxide (POV-alkoxide) clusters, to include the halogenation of mixed-valent vanadium oxide assemblies. These findings build on our previously disclosed results describing the preparation of a mono-anionic chloride-functionalized cluster, [V 6 O 6 Cl(OC 2 H 5 ) 12 ] 1− , by chlorination of [V 6 O 7 (OC 2 H 5 ) 12 ] 2− with AlCl 3 , aimed at understanding the electronic consequences of the introduction of halide-defects in bulk metal oxides ( e.g. VO 2 ). While chlorination of the mixed-valent POV-ethoxide clusters was not possible using AlCl 3 , we have found that the chloride-substituted oxidized derivatives of the Lindqvist vanadium-oxide clusters can be formed using TiCl 3 (thf) 3 with [V 6 O 7 (OC 2 H 5 ) 12 ] n ( n = 1−, 0) or WCl 6 with [V 6 O 7 (OC 2 H 5 ) 12 ] 0 . Characterization of the chloride-containing products, [V 6 O 6 Cl(OC 2 H 5 ) 12 ] n ( n = 0, 1+), was accomplished via 1 H NMR spectroscopy, X-ray crystallography, and elemental analysis. Electronic analysis of the redox series of Cl-doped POV-alkoxide clusters via infrared and electronic absorption spectroscopies revealed all redox events are localized to the vanadyl portion of the cluster, with the site differentiated V III –Cl moiety retaining its reduced oxidation state across a 1.9 V window. These results present new synthetic routes for accessing chloride-doped POV-alkoxide clusters from mixed-valent vanadium oxide precursors.  more » « less
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Dalton Transactions
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National Science Foundation
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