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Irradiation of [Ru(bpy)2(bpSOp)](PF6)2 (where bpy is 2,2'-bipyridine and bpSOp is 1,3-bis(phenylsulfinyl)-propane) results in the formation of two new isomers, namely the S,O- and O,O-bonded species. The crystal structure of the bis-thioether and bis-sulfoxide complexes are reported. NMR spectroscopy of the bis-thioether complex in solution is consistent with the molecular structure determined by diffraction methods. Further, NMR spectroscopy of the bis-sulfoxide complex reveals two conformers in solution, one that is consistent with the solid state structure and a second conformer showing distortion in the aliphatic portion of the chelate ring. Time-resolved visible absorption spectroscopy reveals isomerization time constants of 91 ps in dichloroethane (DCE) and 229 ps in propylene carbonate (PC). Aggregate isomerization quantum yields of 0.57 and 0.42 have been determined in DCE and in PC, respectively. The kinetics of the thermal reversion from the O,O- to S,O-bonded isomer are strongly solvent dependent, occurring with rates of 2.41 × 10-3 and 4.39 × 10-5 s-1 in DCE, and 4.68 × 10-4 and 9.79 × 10-6 s-1 in PC. The two kinetic components are assigned to the two isomers identified in solution. [ABSTRACT FROM AUTHOR]

The complex [Ru(bpy)2(bpSO)](PF6)2, where bpy is 2,2'-bipydine and bpSO is l,2-bis(phenylsulfinyl)ethane, exhibits three distinct isomers which are accessible upon metal-to-ligand charge-transfer (MLCT) irradiation. This complex and its parent, [Ru(bpy)2(bpte)](PF6)2, where bpte is 1,2-bis(phenylthio)ethane, have been synthesized and characterized by UV--visible spectroscopy, NMR, X-ray crystallography, and femtosecond transient absorption spectroscopy. A novel method of 2-color Pump-Repump-Probe spectroscopy has been employed to investigate all three isomers of the bis-sulfoxide complex This method allows for observation of the isomerization dynamics of sequential isomerizations of each sulfoxide from MLCT irradiation of the S,S-bonded complex to ultimately form the 0,0-bonded metastable complex. One-dimensional (l-D) and two-dimensional (2-D) (COSY, NOESY, and TOCSY) 'H NMR data show the thioether and ground state S,S-bonded sulfoxide complexes to be rigorously C2 symmetric and are consistent with the crystal structures. Transient absorption spectroscopy reveals that the S,S to S,0 isomerization occurs with an observed time constant of 56.8 (±7.4) ps. The S,0 to 0,0 isomerization time constant was found to be 59 (±4) ps by pump-repump-probe spectroscopy. The composite S,S- to 0,0-isomer quantum yield is 0.42. [ABSTRACT FROM AUTHOR]