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.