Light-Induced Decarbonylation, Solvolysis, and Isomerization of Ru(L)(CO)₂Cl₂ (L = 2,2‘-Bipyridine and 4,4‘-Dimethyl-2,2‘-bipyridine) in Acetonitrile

Abstract

The photochemical properties of Ru(II) mono(bipyridine) complexes Ru(L)(CO)2Cl2 [L = 2,2'-bipyridine (1, 2) or 4,4'-dimethyl-2,2'-bipyridine (3)] were studied in CH3CN and CH2Cl2. Photochemical ligand substitution reactions occurring in CH3CN were followed by infrared and 1H NMR spectroscopies and cyclic voltammetry. The structures of the photolysis products Ru(bpy)(CO)(CH3CN)Cl2 (4), mer-(CH3CN) Ru(bpy)(CH3CN)3Cl+ (6), and fac-(CH3CN) Ru(dmbpy)(CH3CN)3Cl+ (8) were determined by single-crystal X-ray crystallography. Photosubstitution of the trans (1) and cis (2) Cl isomers of Ru(bpy)(CO)2Cl2 (bpy = 2,2'-bipyridine) led to the same monosubstituted Ru(bpy)(CO)(CH3CN)Cl2 complex (4). Probably some isomerization occurs from the trans Cl isomer. Irradiation in CH2Cl2 led mainly to the dichloro-bridged [Ru(bpy)(CO)Cl2]2 (5) dimer starting from either the trans (1) or cis (2) isomer of Ru(bpy)(CO)2Cl2.