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