Ground‐ and Excited‐State Mixed Valency in a 4,4′‐Bipyridine‐Bridged Bimetallic Di‐Ruthenium Complex

The bimetallic complex trans , trans ‐[{Ru II (py) 4 Cl} 2 (µ‐4,4′‐bpy)](PF 6 ) 2 ( Ru(44b)Ru (PF 6 ) 2 ) was synthesized and studied in its ground‐state and excited‐state mixed‐valence forms, using trans ‐[Ru II (py) 4 Cl(4,4′‐bpy)](PF 6 ) ( Ru(44b) (PF 6 )) as a monometallic reference. X‐ray crystallography, UV–vis‐NIR‐IR spectroelectrochemistry, and femtosecond transient‐absorption spectroscopies were complemented with DFT and TD‐DFT calculations. The 4,4′‐bipyridine bridge was found to promote poor but significant metal–metal electronic coupling in both the ground and excited states, revealed by intervalence charge‐transfer absorptions and by extended MLCT excited‐state lifetimes.