Highly reduced, polyoxo(alkoxo)vanadium(III/IV) clusters

A family of high nuclearity oxo(alkoxo)vanadium clusters in un-precedentedly low oxidation states is reported, synthesised from simple vanadium diketonate precursors in alcohols under solvothermal conditions. Crystal structures of [V-18(O)(12)(OH)(2)- (H2O)(4)(EtO)(22)(O2CPh)(6)(acac)(2)] (1), [V16Na2(O)(18)(EtO)(16)(EtOH)(2)(O2CPh)(6)-(HO2CPh)2](infinity) (2), [V-13(O)(13)(EtO)(15)-(EtOH)(RCO2)(3)] in which R=ada-mantyl (3) or Ph3C (4), and [V-11(O)(12)(EtO)(13)(EtOH)(Ph3CCO2)(2)(MePO3)] (5) are reported, revealing these to be {(V16V2IV)-V-III) (1), {V-9(III) (V3VV)-V-IV} (3 and 4) and ((V3V8IV)-V-III} (5) clusters, while 2 consists of isolated {(V8V8IV)-V-III} clusters bridged into polymeric chains by {Na-2-(OEt)(2)} fragments. Solvothermal conditions are essential to the formation of these species, and the level of oxidation of the isolated clusters is in part controlled by the crystallisation time, with the lowest mean-oxidation-state species being isolated by direct crystallisation on controlled cooling of the reaction solutions.