Metallomacrocycles with a difference : macrocyclic complexes with exocyclic ruthenium(II)-containing domains

The templated synthesis of organic macrocycles containing rings of up to 96 atoms and three 2,2'-bipyridine (bpy) units is described. Starting with the bpy-centred ligands 5,5'-bis[3-(1,4-dioxahept-6-enylphenyl)]-2,2'-bipyridine and 5,5'-bis[3-(1,4,7-trioxadec-9-enylphenyl)]-2,2'-bipyridine, we have applied Grubbs' methodology to couple the terminal alkene units of the coordinated ligands in [FeL(3)](2+) complexes. Hydrogenation and demetallation of the iron(II)-containing macrocyclic complexes results in the isolation of large organic macrocycles. The latter bind {Ru(bpy)(2)} units to give macrocyclic complexes with exocyclic ruthenium(II)-containing domains. The complex [Ru(bpy)(2)(L)](2+) (isolated as the hexafluorophosphate salt), in which L=5,5'-bis[3-(1,4,7,10-tetraoxatridec-12-enylphenyl)]-2,2'-bipyridine, undergoes intramolecular ring-closing metathesis to yield a macrocycle which retains the exocyclic {Ru(bpy)(2)} unit. The poly(ethyleneoxy) domains in the latter macrocycle readily scavenge sodium ions, as proven by single-crystal X-ray diffraction and atomic absorption spectroscopy data for the bulk sample. In addition to the new compounds, a series of model complexes have been fully characterized, and representative single-crystal X-ray structural data are presented for iron(II) and ruthenium(II) acyclic and macrocyclic species.