Reactivity of Organoiridium Tungsten Oxide Clusters with Transition Metal Aquo Cations

Abstract

Organometallic−polyoxometalate (POM) complexes form a unique class of molecular organometallic oxides characterized by the dynamic behavior of the organometallic cations. Herein, we investigated the reactivity of Cp*Iroctatungstate clusters (where Cp* represents pentamethylcyclopentadienyl, C 5 Me 5 − ) with Werner-type transition-metal aquo cations. The addition of Ag + , Co 2+ , Ni 2+ , and M 3+ (M = Cr, Fe, or In) cations to the aqueous solution of Cp*Ir-octatungstate clusters resulted in the formation of [{Ag) 2 (M = Cr, 3-Cr; Fe, 3-Fe; or In, 3-In), respectively. All clusters share the same cubane-type {Cp*IrW 3 O 12 (OH)} 5− building block, representing the first examples of organoiridium-POMs functionalized by transition-metal aquo cations. These compounds are insoluble in water, facilitating the evaluation of their heterogeneous wateroxidation properties. Notably, 2-Co generates the highest catalytic water oxidation current. This work provides a new synthetic method to introduce metal−aquo complexes on an organometallic oxide cluster, producing multimetallic molecules that model the catalytic sites of complex oxides.