Reductive Formation of a Vanadium(IV/V) Oxide Cluster Complex [V₈O₁₉(4,4′‑^tBubpy)₃] Having a C₃‑Symmetric Propeller-Shaped Nonionic V₈O₁₉ Core

A novel C₃-symmetric propeller-shaped vanadium­(IV/V) oxide cluster complex, [V₈O₁₉(4,4′-^tBubpy)₃] (V₈′), has been synthesized from the reaction of the windmill-shaped vanadium­(V) oxide cluster complex [V₈O₂₀(4,4′-^tBubpy)₄] (V₈) with PPh₃ under N₂, whereas refluxing V₈ in methanol or ethanol under N₂ provides tetranuclear oxido­(alkoxido)­vanadium­(IV/V) complexes [V₄O₆(OR)₆(4,4′-^tBubpy)₂] [R = Me (V₄′-Me) and Et (V₄′-Et)]. The mixed-valent vanadium­(IV/V) clusters V₈′ and V₄′ are converted back to V₈ under O₂. Interconversions of V₄′ and the oxido­(alkoxido)­vanadium­(V) complexes [V₄O₈(OMe)₄(4,4′-^tBubpy)₂] (V₄) and [V₇O₁₇(OEt)­(4,4′-^tBubpy)₃] (V₇-Et) are also presented.