The Excited‐State Creutz–Taube Ion

The excited‐state version of the Creutz–Taube ion was prepared via visible light excitation of [(NH(3))(5)Ru(II)(μ‐pz)Ru(II)(NH(3))(5)](4+). The resulting excited state is a mixed valence {Ru(III–δ)(μ‐pz⋅(−))Ru(II+δ)} transient species, which was characterized using femtosecond transient absorption spectroscopy with vis‐NIR detection. Very intense photoinduced intervalence charge transfers were observed at 7500 cm(−1), revealing an excited‐state electronic coupling element H(DA)=3750 cm(−1). DFT calculations confirm a strongly delocalized excited state. A notable consequence of strong electron delocalization is the nanosecond excited state lifetime, which was exploited in a proof‐of‐concept intermolecular electron transfer. The excited‐state Creutz–Taube ion is established as a reference, and demonstrates that electron delocalization in the excited state can be leveraged for artificial photosynthesis or other photocatalytic schemes based on electron transfer chemistry.