Reactivity of Organoiridium Tungsten Oxide Clusters with Transition Metal Aquo Cations.
null SugiartoRyoji MitsuhashiMasahiro SadakanePublished in: Inorganic chemistry (2024)
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*Ir-octatungstate 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(OH 2 ) 2 } 2 {Cp*Ir(OH 2 )} 2 {Cp*IrW 3 O 12 (OH)} 2 (WO 2 ) 2 ] ( 1 ), Co 1.5 K 0.8 Na 0.2 [{ trans -Co(OH 2 ) 2 }{Cp*IrW 3 O 12 (OH)} 2 (WO 2 ) 1.3 { cis -Co(OH 2 ) 2 } 0.7 ] ( 2-Co ), Ni 0.2 K 1.4 Na 0.2 [{Ni(OH 2 ) 4 } 2 {Cp*IrW 3 O 12 (OH)} 2 (WO 2 ) 1.1 { cis -Ni(OH 2 ) 2 } 0.9 ] ( 2-Ni ), and [{M(OH 2 ) 4 } 2 {Cp*IrW 3 O 12 (OH)} 2 { cis -M(OH 2 ) 2 } 2 ](NO 3 ) 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 water-oxidation 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.