Light-induced decarbonylation, solvolysis, and isomerization of Ru(L)(CO)(2)Cl-2 (L=2,2 '-bipyridine and 4,4 '-dimethyl-2,2 '-bipyridine) in acetonitrile

The photochemical properties of Ru(II) mono(bipyridine) complexes Ru(L)(CO) (2)Cl-2 [L = 2,2'-bipyridine (1, 2) or 4,4'-dimethyl-2,2'-bipyridine (3)] w ere studied in CH3CN and CH2Cl2. Photochemical ligand substitution reaction s occurring in CH3CN were followed by infrared and H-1 NMR spectroscopies a nd cyclic voltammetry. The structures of the photolysis products Ru(bpy)(CO )(CH3CN)Cl-2 (4), mer-(CH3CN) Ru(bpy)(CH3CN)(3)Cl+ (6), and fac(CH3CN) Ru(d mbpy)(CH3CN)(3)Cl+ (8) were determined by single-crystal X-ray crystallogra phy. Photosubstitution of the trans (1) and cis (2) Cl isomers of Ru(bpy)(C O)(2)Cl-2 (bpy = 2,2'-bipyridine) led to the same monosubstituted Ru(bpy)(C O)(CH3CN)Cl-2 complex (4). Probably some isomerization occurs from the trai ts Cl isomer. Irradiation in CH2Cl2 led mainly to the dichloro-bridged [Ru( bpy)(CO)Cl-2](2) (5) dimer starting from either the trans (1) or cis (2) is omer of Ru(bpy)(CO)(2)Cl-2.