Highly self-organized electron transfer from an iridium complex to p-benzoquinone due to formation of a π-dimer radical anion complex triply bridged by scandium ions

Unusually high kinetic order was observed in self-organized Sc³⁺-promoted electron transfer from tris(2-phenylpyridine)iridium(III) [Ir(ppy)₃] to p-benzoquinone (Q) in propionitrile, third-order with respect to the concentration of Sc³⁺ and second-order with respect to the concentration of Q, to produce a π-dimer semiquinone radical anion complex that is triply bridged by three Sc³⁺ ions (Q^•--3Sc³⁺-Q).