Irreversible but noncovalent Ru(II)-pyridine bond: Its use for the formation of [2]-catenanes

The reaction between ligand 1, which consists of two terminal pyridines attached to a central 1,10-phenanthroline (phen), and the complex Ru(phen)(2)(CH3CN)(2)(PF6)(2) has been studied. A new ruthenium containing metallamacrocycle has been obtained and fully characterized. Despite the relatively poor yield for the cyclization process involving the ruthenium center (20%), this strategy led to the synthesis of two different kinds of [2]-catenane. The first example reported in this article is a bimetallic Cu(I)/Ru(II) catenane 5(3+) consisting of a purely organic ring interlocked with the ruthenium(II)-incorporating metallacycle. Complex 5(3+) was selectively demetalated at the Cu(I) center to lead to the free Ru(II)-containing catenane. A trimetallic Ru(II)/Cu(I)/Ru(II) catenane 8(5+) was also synthesized showing that this approach is reliable and promising for the elaboration of photoactive multicomponent systems.