Cation-Assisted Ligand Photosubstitution in Transition-Metal Complexes. Photoreactions of Ru(bpy)32+ with Ag+ in Acetonitrile

Article abstract of DOI:10.1021/j100214a034

Irradiation of Ru(bpy)3²⁺ in the presence of Ag⁺ in acetonitrile leads to the photosubstitution product Ru(bpy)2(CH3CN)2²⁺.The reaction does not occur in the absence of Ag⁺ or acetonitrile; although Ag⁺ quenches the luminescent MLCT state of Ru(bpy)3²⁺, a kinetic analysis indicates the photosubstitution does not originate from this excited state.The most reasonable mechanism for the process involves decay of the MLCT state via a d-d excited state to a ligand-labilized intermediate which is interpreted by Ag⁺ in a process which assists the substitution by removal of a bpy ligand.This mechanism is thus parallel to anion-induced substitution reactions which evidently proceed via competitive anion-ligand capture of the same or similar intermediates.