Photochemical or thermal chelate exchange in the ruthenium coordination sphere of complexes of the Ru(phen)₂L family (L = diimine or dinitrile ligands)

Complexes of the type Ru(phen)₂L²⁺, where L is a substituted bipyridine family member, have been prepared, and their photochemical substitution reactions have been investigated. In the presence of a bis-benzonitrile derivative, acting as a bidentate chelate, photoexpulsion of L is performed under the action of visible light, with quantitative formation of new complexes of the type Ru(phen)₂L′²⁺ (L′ = bis-nitrile ligand). Several complexes have been characterized by X-ray crystallography. In particular, the bis-benzonitrile complexes could be crystallized, and the structure of these compounds, containing a 13-, 14-, or 15-membered metal incorporating ring, was obtained. By heating Ru(phen)₂L′²⁺ with a bipy derivative in refluxing ethylene glycol, quantitative formation of the starting complex [Ru(phen)₂L²⁺] was carried out. The present series of compounds presents properties that could be profitably used in the design and construction of multicomponent systems acting as photochemically driven molecular machines.