Reductive Formation of a Vanadium(IV/V) Oxide Cluster Complex [V₈O₁₉(4,4′‑^<i>t</i>Bubpy)₃] Having a <i>C</i>₃‑Symmetric Propeller-Shaped Nonionic V₈O₁₉ Core

A novel <i>C</i>₃-symmetric propeller-shaped vanadium­(IV/V) oxide cluster complex, [V₈O₁₉(4,4′-^<i>t</i>Bubpy)₃] (<b>V</b>_<b>8</b><b>′</b>), has been synthesized from the reaction of the windmill-shaped vanadium­(V) oxide cluster complex [V₈O₂₀(4,4′-^<i>t</i>Bubpy)₄] (<b>V</b>_<b>8</b>) with PPh₃ under N₂, whereas refluxing <b>V</b>_<b>8</b> in methanol or ethanol under N₂ provides tetranuclear oxido­(alkoxido)­vanadium­(IV/V) complexes [V₄O₆(OR)₆(4,4′-^<i>t</i>Bubpy)₂] [R = Me (<b>V</b>_<b>4</b><b>′-Me</b>) and Et (<b>V</b>_<b>4</b><b>′-Et</b>)]. The mixed-valent vanadium­(IV/V) clusters <b>V</b>_<b>8</b><b>′</b> and <b>V</b>_<b>4</b><b>′</b> are converted back to <b>V</b>_<b>8</b> under O₂. Interconversions of <b>V</b>_<b>4</b><b>′</b> and the oxido­(alkoxido)­vanadium­(V) complexes [V₄O₈(OMe)₄(4,4′-^<i>t</i>Bubpy)₂] (<b>V</b>_<b>4</b>) and [V₇O₁₇(OEt)­(4,4′-^<i>t</i>Bubpy)₃] (<b>V</b>_<b>7</b><b>-Et</b>) are also presented