Excited state isomerization in a new ruthenium chelating sulfoxide complex

Electrochemical and photochemical studies of a photochromic complex with a chelating sulfoxide are reported. Electrochemical data do not support evidence for isomerization following electrochemical oxidation. However, irradiation of solutions containing [Ru(bpy)2(PhNSO)](PF6)2 (bpy is 2,2′-bipyridine, PhNSO is N-benzylidine-2-(ethylsulfinyl)ethanamine) demonstrate excited state S → O isomerization. The S-bonded absorption maximum is 382 nm, while the O-bonded isomer features absorption maxima at 360 and 486 nm. The quantum yield of isomerization is 0.033 and the S-bonded isomer is emissive at low temperature (77 K). These data and an electronic structural model explaining this reactivity are introduced.