Neutral and Cationic V<sup>IV</sup>/V<sup>V</sup> Mixed-Valence
Alkoxo-polyoxovanadium Clusters [V<sub>6</sub>O<sub>7</sub>(OR)<sub>12</sub>]<i><sup>n</sup></i><sup></sup><i><sup>+</sup></i><sup></sup> (R = −CH<sub>3</sub>,
−C<sub>2</sub>H<sub>5</sub>): Structural, Cyclovoltammetric and IR-Spectroscopic
Investigations on Mixed Valency in a Hexanuclear Core
Charles Daniel
Hans Hartl
10.1021/ja052902b.s001
https://acs.figshare.com/articles/dataset/Neutral_and_Cationic_V_sup_IV_sup_V_sup_V_sup_Mixed_Valence_Alkoxo_polyoxovanadium_Clusters_V_sub_6_sub_O_sub_7_sub_OR_sub_12_sub_i_sup_n_sup_i_sup_sup_i_sup_sup_i_sup_sup_R_CH_sub_3_sub_C_sub_2_sub_H_sub_5_sub_Structural_Cyclovoltammetric_and_IR_Spectros/3263674
The alkoxo-polyoxovanadium clusters [V<sub>6</sub>O<sub>7</sub>(OR)<sub>12</sub>] (R = −CH<sub>3</sub>, −C<sub>2</sub>H<sub>5</sub>) are fully alkylated
polyoxometalate derivatives comprising a hexavanadate core with the vanadium ions organized in an
octahedral fashion, a classic isopolyoxometalate structure (Lindqvist) which as an entity is not known for
vanadium. The clusters are highly redox-active compounds, displaying a large number of thermodynamically
stable redox isomers of which the chemical syntheses and structural characterization of the neutral and
cationic V<sup>IV</sup>/V<sup>V</sup> mixed-valence species [V<sup>IV</sup><sub>(4</sub><sub>-</sub><i><sub>n</sub></i><sub>)</sub>V<sup>V</sup><sub>(2+</sub><i><sub>n</sub></i><sub>)</sub>O<sub>7</sub>(OR)<sub>12</sub>]<i><sup>n</sup></i><sup>+</sup>[SbCl<sub>6</sub>]<i><sub>n</sub></i> (R = −CH<sub>3</sub>, <i>n</i> = 0, 1; R = −C<sub>2</sub>H<sub>5</sub>,
<i>n</i> = 0, 1, 2) are presented here. Neutral and positively charged clusters remain exceptional in the field of
polyoxometalate chemistry. Results obtained from cyclic voltammetry, infrared spectroscopy, and from
valence sum calculations conducted on X-ray structural data classify these clusters as class II mixed-valence compounds. Their highly symmetrical molecular structures make them particularly interesting as
model compounds for the investigation of intervalence charge transfer and electron delocalization in the
hexanuclear core. Furthermore, the large number of isostructural redox isomers affords a high variability
in d-electron content. Accordingly, a dependency could clearly be established between the extent of electron
delocalization and the V<sup>IV</sup>/V<sup>V</sup> ratio in a cluster species. A further interesting observation concerns the neutral
ethoxo compound [V<sup>IV</sup><sub>4</sub>V<sup>V</sup><sub>2</sub>O<sub>7</sub>(OC<sub>2</sub>H<sub>5</sub>)<sub>12</sub>] (<b>3</b>) which exhibits a crystallographic phase transition accompanied
by the conversion from a structure at 173 K with fully localized valencies to a room-temperature modification
displaying complete d-electron delocalization.
2005-10-12 00:00:00
V IV 4 V V 2 O 7
compound
valence sum calculations
electron delocalization
core
intervalence charge transfer
Neutral
CH
alkylated polyoxometalate derivatives
V 6 O 7
cluster
species
isostructural redox isomers
II
vanadium
OC 2 H 5