Metallostars containing {Ru(bpy)3} motifs

Two new ligands designed to act as the core for metallostars based upon multiple bpy (bpy = 2,2'-bipyridine) metal-binding domains have been prepared. The first ligand 6 consists of a 1,3,5-triazine bearing three bpy metal-binding domains and was prepared inter alia using Stille methodology. All attempts to form complexes of 6 were unsuccessful. In contrast, a non-planar core compound based upon a tetraphenylmethane moiety bearing four bpy domains, also prepared using Stille couplings, was shown to form a tetraruthenametallostar complex containing four {Ru(bpy)(3)} motifs. Each of the {Ru(bpy)(3)} motifs is chiral, possessing Delta or Lambda chirality and detailed NMR studies indicate that the complex is formed with little or no diastereoselectivity leading to a mixture of diastereomers and a fuzzy stereochemistry. (C) 2000 Elsevier Science S.A. All rights reserved.